A LEVEL GEOGRAPHY REVISION GUIDE Paper 1: Physical ..., Study notes of Geography

Download A LEVEL GEOGRAPHY REVISION GUIDE Paper 1: Physical ... and more Study notes Geography in PDF only on Docsity! A LEVEL GEOGRAPHY REVISION GUIDE Paper 1: Physical Geography 2020 THE WATER AND CARBON CYCLES Water cycles 1.1 The global hydrological cycle is of enormous importance to life on earth.  The global hydrological cycle’s operation as a closed system (inputs, outputs, stores and flows) driven by solar energy and gravitational potential energy.  The relative importance and size (percentage contribution) of the water stores (oceans, atmosphere, biosphere, cryosphere, groundwater and surface water) and annual fluxes between atmosphere, ocean and land.  The global water budget limits water available for human use and water stores have different residence times; some stores are non-renewable (fossil water or cryosphere losses). 1.2 The drainage basin is an open system within the global hydrological cycle.  The hydrological cycle is a system of linked processes: inputs (precipitation patterns and types: orographic, frontal, convectional) flows (interception, infiltration, direct runoff, saturated overland flow, throughflow, percolation, groundwater flow) and outputs (evaporation, transpiration and channel flow).  Physical factors within drainage basins determine the relative importance of inputs, flows and outputs (climate, soils, vegetation, geology, relief).  Humans disrupt the drainage basin cycle by accelerating processes (deforestation; changing land use) and creating new water storage reservoirs or by abstracting water. (Amazonia) 1.3 The hydrological cycle influences water budgets and river systems at a local scale.  Water budgets show the annual balance between inputs (precipitation) and outputs (evapotranspiration) and their impact on soil water availability and are influenced by climate type (tropical, temperate, polar examples).  River regimes indicate the annual variation of discharge of a river and result from the impact of climate, geology and soils as shown in regimes from contrasting river basins. (Yukon, Amazon, Indus).  Storm hydrographs shape depends on physical features of drainage basins (size, shape, drainage density, rock type, soil, relief and vegetation) as well as human factors (land use and urbanisation). (P: the role of planners in managing land use). 2.1 Deficits within the hydrological cycle result from physical processes but can have significant impacts.  The causes of drought, both meteorological (short-term precipitation deficit, longer trends, ENSO cycles and hydrological.  The contribution human activity makes to the risk of drought: over-abstraction of surface water resources and ground water aquifers. (Sahelian drought; Australia).  The impacts of drought on ecosystem functioning (wetlands, forest stress) and the resilience of these ecosystems. 2.2 Surpluses within the hydrological cycle can lead to flooding, with significant impacts for people.  Meteorological causes of flooding, including intense storms leading to flash flooding, unusually heavy or prolonged rainfall, extreme monsoonal rainfall and snowmelt.  Human actions that can exacerbate flood risk (changing land use within the river catchment, mismanagement of rivers using hard engineering systems.)  Damage from flooding has both environmental impacts (soils and ecosystems) and socio- economic impacts (economic activity, infrastructure and settlement). (UK flood events 2007 or 2012). 2.3 Climate change may have significant impacts on the hydrological cycle globally and locally.  Climate change affects inputs and outputs within the hydrological cycle: trends in precipitation and evaporation.  Climate change affects stores and flows, size of snow and glacier mass, reservoirs, lakes, amount of permafrost, soil moisture levels as well as rates of runoff and stream flow. 3.2 There are implications for human wellbeing from the degradation of the water and carbon cycles.  Forest loss has implications for human wellbeing but there is evidence that forest stores are being protected and even expanded, especially in countries at higher levels of development (environmental Kuznets’ curve model). (A: attitudes of global consumers to environmental issues)  Increased temperatures affect evaporation rates and the quantity of water vapour in the atmosphere with implications for precipitation patterns, river regimes and water stores (cryosphere and drainage basin stores) (Arctic) (F: uncertainty of global projections).  Threats to ocean health pose threats to human wellbeing, especially in developing regions that depend on marine resources as a food source and for tourism and coastal protection. 3.3 Further planetary warming risks large-scale release of stored carbon, requiring responses from different players at different scales.  Future emissions, atmospheric concentration levels and climate warming are uncertain owing to natural factors (the role of carbon sinks), human factors (economic growth, population, energy sources) and feedback mechanisms (carbon release from peatlands and permafrost, and tipping points, including forest die back and alterations to the thermohaline circulation). (F: uncertainty of global projections)  Adaptation strategies for a changed climate (water conservation and management, resilient agricultural systems, land-use planning, flood-risk management, solar radiation management) have different costs and risks.  Re-balancing the carbon cycle could be achieved through mitigation (carbon taxation, renewable switching, energy efficiency, afforestation, carbon capture and storage) but this requires global scale agreement and national actions both of which have proved to be problematic. (A: attitudes of different countries, TNCs and people) Glossary of Definitions Acidification - The gradual reduction of pH of the oceans, due to dissolving carbon dioxide from the atmosphere. Afforestation - Planting trees and vegetation in the aim of increasing forest cover. Anticyclone- A system of high pressure, causing high temperatures and unseasonably high evaporation rates. Aquifer- A permeable or porous rock which stores water. Biofuel - Burning crops and vegetation for electricity and heat. Carbon Capture & Storage (CCS) - The capture of carbon dioxide emissions directly from the factory, pumped into disused mines rather than being released into the atmosphere. Carbon Fluxes- The movement of carbon between stores. Carbon Neutral- A process that has no net addition of carbon dioxide to the environment. Carbon Stores- Places where carbon accumulates for a period of time such as rocks and plant matter. Channel Flow- Water flowing in a rivulet, stream or river. Choke Points- Points in the logistics of energy and fuel that are prone to restriction. Combustion- The process of burning a substance, in the presence of oxygen, to release energy. Convectional Precipitation- Solar radiation heats the air above the ground, causing it to rise, cool & condense forming precipitation (often as thunderstorms). Cryosphere- The global water volume locked up within a frozen state (i.e. snow and ice). Decomposition- The break down of matter, often by a decomposer which releases carbon dioxide through their own respiration. Depression- A system of low pressure, with fronts of precipitation where low and high pressure air masses meet. Desalination Plant- The conversion of seawater to freshwater, suitable for human consumption. Desublimation- The change of state of water from gas to solid, without being a liquid (the opposite process to sublimation). Drainage Basin- The area of land drained by a river and its tributaries. Drainage Density- The total length of all rivers & streams divided by the area of the drainage basin. Drought- An extended period of deficient rainfall relative to the statistical average for the region (UN). Economic Water Scarcity- When water resources are available but insufficient economic wealth limits access to it. Energy Mix- The composition of a country’s energy sources. Energy Security- The ownership and full control of a country’s energy source, production and transportation. Energy Pathway- The movement of energy from its extraction or source, through pipes, freight logistics or cabling. Energy Players- Key companies and individuals who own, distribute and sell energy and energy sources. Enhanced Greenhouse Effect- The build-up of greenhouse gases in the atmosphere, reducing the amount of solar radiation reflected into space. ENSO Cycles- El Niño Southern Oscillations - naturally occurring phenomena that involves the movement of warm water in the Equatorial Pacific. Evapotranspiration- The combined total moisture transferred from the Earth to the atmosphere, through evaporation and transpiration. Frontal Precipitation- Where air masses of different temperatures meet at a front, one mass will be forced over another, causing precipitation beneath the front. Global Hydrological Cycle- The continuous transfer of water between land, atmosphere and oceans. The Earth is a closed system. Groundwater Flow- Water moving horizontally through permeable or porous rock due to gravity. Hydrological Drought- Insufficient soil moisture to meet the needs of vegetation (crops, trees, plants) at a particular time Infiltration- The movement of water vertically through the pores in soil. Integrated Drainage Basin Management- Establishing a frame of coordinated efforts between administrations (e.g. local government) and stakeholders (e.g businesses) to achieve balanced management of a basin (World Bank). Inorganic Carbon- Carbon stored in carbonated rocks. Interception- Raindrops are prevented from falling directly onto the ground, instead hitting the leaves of a tree. Meteorological Drought- When long-term precipitation trends are below average. Monsoon- The drastic variation between wet and dry seasons for sub-tropical areas, caused by a changed prevailing wind. Can lead to annual flooding. Non-Renewable- A source of energy that can only be used once to generate electricity or takes thousands of years to replace e.g. Fossil Fuels. Nuclear Fusion- The process of joining atomic nuclei together, to produce energy. PEC- Oil and Petroleum exporting countries. An organisation that supports and coordinates fossil fuel exporting countries. Open System- A system affected by external flows and inputs (such as a drainage basin, or a sediment cell). Organic Carbon- Carbon stored in plant material and living organisms. Outgassing- The release of dissolved carbon dioxide (e.g. at plate boundaries, warming the oceans). Percolation- Water moving vertically from soil into permeable rock. Photosynthesis- The process of converting carbon dioxide and water into glucose and oxygen. All plants and some organisms rely on this process to survive. Physical Water Scarcity- A physical lack of available freshwater which cannot meet demand. Phytoplankton- Small organisms that rely on photosynthesis to survive, so intake carbon dioxide from the atmosphere. Primary Energy- The initial source of energy, as it is naturally found. This could be natural ores, water, crops or radioactive material. Relief Precipitation- Precipitation caused when air masses are forced to rise over high land, determined by the relief/ morphology of the land. Renewable- Primary energy that can be re-used to produce electricity or has a short lifetime, therefore any used can be replaced quickly e.g. Hydroelectric, biomass, solar. Respiration- The process of converting glucose and oxygen into carbon dioxide and energy. Some organisms rely on respiration to survive. River Regime- The pattern of river discharge over a year. Runoff- Water flowing over the surface of the ground eg. after precipitation or snowmelt. Salinisation- Where salt water contaminates freshwater stores or soils, creating saline conditions and reducing human use/ consumption. Saltwater Encroachment- The movement of saltwater into freshwater aquifers or soils. This may be caused by sea level rise, storm surges or over-extraction. Secondary Energy- The product of primary energy, mostly electricity. Sequestration- The transfer of carbon from the atmosphere to stores elsewhere - living biosphere, inorganic rocks, etc. Smart Irrigation- Providing crops with a water supply less than optimal, to make crops resistant to water shortages. Storm Hydrograph- Variation of river discharge over a short period of time (days). Sublimation -The change of state of water from solid to a gas, without being a liquid. Thermohaline Circulation- The movement of volumes of seawater from cold deep water to warm water surface water. Throughflow-Water moving horizontally through the soil, due to gravity. Tipping Point- A critical threshold where any changes to a system after the tipping point are irreversible. Transpiration- The process through which water evaporates through the stomata in plants' leaves. Urbanisation- The growth of populations in towns and cities. Water Budget- The annual balance between inputs and outputs within a system. Water Conservation- Strategies to reduce water usage and demand. Water Recycling- The treatment and purification of waste water, to increase supply. Water Scarcity- There are limited renewable water sources (between 500 and 1000 cubic metres per capita per year). Water Security- The ability to protect and access a sustainable source to adequately meet demand. Water Sharing Treaty- International agreements for transboundary sources. Water Transfer- Hard engineering projects, such as pipelines or aqueducts, that divert water between basins to meet demand. Watershed- The boundary between neighbouring drainage basins. Streamflow - Water that moves through established channels- Fast Stemflow - Flow of water that has been intercepted by plants or trees, down a stem, leaf, branch or other part of a plant - Fast. Stores Soil Water- Water stored in the soil which is utilised by plants- Mid-term Groundwater- Water that is stored in the pore spaces of rock- Long-term River Channel - Water that is stored in a river - Short-term Interception - Water intercepted by plants on their branches and leaves before reaching the ground - Short-term Surface Storage- Water stored in puddles, ponds, lakes etc. - Variable The water table is the upper level at which the pore spaces and fractures in the ground become saturated. It is used by researchers toassess drought conditions, health of wetland systems, success of forest restoration programmes etc. The Water Balance The water balance is used to express the process of water storage and transfer in a drainage basin system and uses the formula: Precipitation = Total Runoff + Evapotranspiration +/- (change in) Storage It is important to use the water balance in your answers and to know what the balance is affected by, as it could be applied to explain droughts or floods. The water balance of an area will change dependent on physical factors, especially during seasonal variations of temperature and precipitation. The amount of precipitation in comparison with the amount of runoff and evapotranspiration affects change in storage. Changes to the Water Cycle The water cycle is impacted on a local scale by: ● Deforestation - There isless interception by trees so surface runoff increases. The soil is no longer held together by roots, so soil water storage decreases. There are fewer plants so transpiration decreases. ● Storm Events - Large amounts of rainfall quickly saturate the ground to its field capacity . No more water can infiltrate the soil, increasing the surface runoff. Storm events are therefore less effective at recharging water stores than prolonged rainfall. In 24 hours if 20mm of rain fell evenly this would infiltrate the soil and percolate into the groundwater stores as well, with lowsurface runoff. In 1 hour if 20mm of rain fell, there would be less water infiltrating the soil and percolating into the rocks, reducing the replenishment of groundwater stores, but increasing runoff. ● Seasonal Changes: ○ Spring: More vegetation growth so more interception by vegetation. ○ Summer: Likely to be less rain in summer. Ground may be harder and therefore more impermeable encouraging surface runoff. ○ Autumn: Less vegetation growth so less interception. Seasonally more rainfall. ○ Winter: Frozen ground may be impermeable and encourage runoff. Snow discourages runoff and takes time to melt, slowing down the processes that occur within the water cycle. ● Agriculture: ○ Pastoral farming relates to livestock. A good way to remember is Pastoral farmers farm Pigs. Livestock such as Pigs, cattle, goats, sheep etc, trample the ground reducing infiltration. ○ Arable farming relates to crops.Ploughing increases infiltrationby creating a looser soil, which decreases surface runoff. However, digging drainage ditches (often seen around field edges) increases surface runoff and streamflow. ○ Hillside terracing (for rice padi fields) increases surface water storage and therefore decreases runoff. ○ Irrigation (the movement of water by human intervention through tunnels and other conduits) can lead to groundwater depletion. ● Urbanisation: ○ Creating roads and buildings which have impermeable surfaces and are likely to have drains creates impermeable surfaces that reduce infiltration but increase surface runoff, reducing lag-time and increasing the flood risk. ○ Green roofs and Sustainable Urban Drainage Systems (SUDS) use grass and soil to reduce the amount of impermeable surfacesare helping to tackle the problem of urban flooding in some cities. The Soil Water Budget The soil water budgetshows the annual balance between inputs and outputs in the water cycle and their impact on soil water storage/availability. The budget is never the same due to varying conditions year on year and the process is affected by how much rainfall/dry weather there is the previous year. The water budget is also dependent on type, depth and permeability of the soil and bedrock. The maximum possible level of storage of water in the soil is field capacity.Once the field capacity is reached, any rainfall after this will not infiltrate the soil and is likely to cause flooding. The water budget is dependent on type, depth and permeability of the soil and bedrock. Seasonal Variation of the Soil Water Budget Autumn: In Autumn, there is a greater input from precipitation than there is an output from evapotranspiration as deciduous trees lose their leaves and the cooler temperatures mean that the plants photosynthesise less. Soil moisture levels increaseand a water surplusoccurs. Winter: Potential evapotranspiration from plants reaches a minimum due to the colder temperatures and the precipitation continues to refill the soil water stores. Infiltration and percolation will also refill the water table. Spring: Around February and March, plants start to grow again and potential evapotranspiration increases as temperatures get higher and plants start photosynthesising more. There is still a water surplus in this time. Summer: The hotter weather leads to utlisation of soil water as evapotranspiration peaks and rainfall is at a minimum. The output from evapotranspiration is greater than the input from precipitation so the soil water stores are depleting. A water deficit may occurif there is a long hot summer and spring, a lack of winter rainfall, or a drought the year before. The cycle then repeats. Cryospheric Processes: ● In the past glaciers and icecaps have stored significant proportions of freshwater through the process of accumulation. ● Currently, almost all of the world’s glaciers are shrinking, causing sea levels to rise ● If all the world’s glaciers and icecaps were to melt, sea levels would rise by around 60 metres. The UK with a 60m sea level rise Human Impacts Farming Practices: ● Ploughing breaks up the surface, increasing infiltration. ● Arable farming (crops) can increase interception and evapotranspiration. ● Pastoral (animal) farming compacts soil, reducing infiltration and increasing runoff. ● Irrigation removes water from local rivers, decreasing their flow. Land Use Change: ● Deforestation (e.g. for farming) reduces interception, evapotranspiration and but infiltration increases (dead plant material in forests usually prevents infiltration). ● Construction reduces infiltration and evapotranspiration, but increases runoff. Water Abstraction (water removed from stores for human use): ● This reduces the volume of water in surface stores (e.g. lakes). ● Water abstraction increases in dry seasons (e.g. water is needed for irrigation). ● Human abstraction from aquifers as an output to meet water demands is often greater than inputs to the aquifer, leading to a decline in global long-term water stores. The combination of human activity and natural variation will cause the greatest changes to the water cycle. Flood Hydrographs A flood hydrograph is used to represent rainfall for the drainage basin of a river and the discharge of the same river on a graph. The key components are labelled above and explained below: ● Discharge: The volume of waterpassing through a cross-sectional point of the riverat any one point in time, measured in Cubic Metres Per Second (Cumecs). Made up of the base flow and stormflow. ● Rising Limb: The line on the graph that represents the discharge increasing. ● Falling Limb: The line on the graph that represents the discharge decreasing. ● Lag Time: The time between peak rainfalland peak discharge. ● Baseflow: The level of groundwater flow. ● Stormflow: Comprised of overland flowand throughflow. ● Bankfull Discharge: The maximum capacity of the river. If discharge exceeds this then the river will burst its banks and be in flood. Flashy Hydrograph: Short lag time and high peak discharge, most likely to occur during a storm event, with favourable drainage basin characteristics Subdued Hydrograph: Long lag timeand low peak discharge Features of Flashy and Subdued Hydrographs: Flashy: Subdued: ● Short lag time ● Long lag time ● Steep rising and falling limb ● Gradually rising and falling limb ● Higher flood risk ● Lower flood risk ● High peak discharge ● Low peak discharge Some of the factors which would increase surface runoff of a river, decrease lag time and increase peak discharge and therefore act to create a flashy hydrograph are shown on the Ordnance Survey (OS) Map, and others are listed below: Natural: ● High Rainfall Intensity - Higher discharge potentialfrom the river and more likely for soil to reach its field capacity, thus increasing surface runoff and decreasing the lag time. ● Antecedent Rainfall (Rainfall that occurs before the studied rainfall event. e.g. rain the day before) - Increased surface runoff as ground is saturated and soil has reached its field capacity. ● Impermeable Underlying Geology - Decreased percolationand therefore greater levels of throughflow. ● High Drainage Density - Many tributariesto main river, increasing speed of drainage and decreasing the lag time. ● Small Basin - Rainfall reaches the central river more rapidly, decreasing the lag time. You should be aware of how the carbon cycle functions in a lithosere environment, as shown below. The climatic climax is the final stage of the sere where environmental equilibrium is achieved. In most of the UK this would be a woodland, but another example would be a rainforest. When a sere reaches a climatic climax, the ecosystem is fully developed and stable, and it will not change dramatically as the equilibrium will counteract any change (unless there is a major climatic or geographical change). Different seres relate to particular environments and include: Lithosere - Bare rock Halosere - Salty environment Psammosere - Sand coastal environment Hydrosere - Freshwater environment For example, in a lithosere over time a soil builds up on the rock from decaying organic matter. Plants colonise the soil and the soil continues to build up until it is deep enough for trees to colonise. Lithosere succession The Carbon Cycle: Global Scale A carbon sink is any store which takes in more carbon than it emits, so anintact tropical rainforest is an example. A carbon source is any store that emits more carbon than it stores so a damaged tropical rainforest is an example. Main Carbon Stores (In order of magnitude): ● Marine Sediments and Sedimentary Rocks - Lithosphere - Long-term ○ Easily the biggest store. 66,000 - 100,000 million billion metric tons of carbon. The rock cycle and continental drift recycle the rock over time, but this may take thousands, if not millions of years. ● Oceans - Hydrosphere - Dynamic ○ The second biggest store contains a tiny fraction of the carbon of the largest store. 38,000 billion metric tons of carbon. The carbon is constantly being utilised by marine organisms, lost as an output to the lithosphere, or gains as an input from rivers and erosion. ● Fossil Fuel Deposits - Lithosphere - Long-term but currently dynamic ○ Fossil fuel deposits used to be rarely changing over short periods of time, but humans have developed technology to exploit them rapidly, though 4000 billion metric tons of carbon remain as fossil fuels. ● Soil Organic Matter - Lithosphere - Mid-term ○ The soil can store carbon for over a hundred years, but deforestation, agriculture and land use change are affecting this store. 1500 billion metric tons of carbon stored. ● Atmosphere - Dynamic ○ Human activity has caused CO₂ levels in the atmosphere to increase by around 40% since the industrial revolution, causing unprecedented change to the global climate. 750 billion metric tons of carbon stored. ● Terrestrial Plants - Biosphere - Mid-term but very dynamic ○ Vulnerable to climate change and deforestation and as a result carbon storage in forests is declining annually in some areas of the world. 560 billion metric tons of carbon. The lithosphere is the main store of carbon, with global stores unevenly distributed. For example, the oceans are larger in the southern hemisphere, and storage in the biosphere mostly occurs on land. Terrestrial plant storage is focussed in the tropics and the northern hemisphere. Different amounts of carbon are stored worldwide and one of the stores that is currently changing is trees: Key: Pink is forest area lost. Purple is forest area gained.Source: Global Forest Watch The map shows how forests are declining in the tropical areas in the southern hemisphere and growing in the northern hemisphere. This is supported by data which shows that tropical areas such as Brazil and Indonesia have seen a decrease in carbon stocks of around 5 Gigatons of Carbon (GtC) in the last 25 years, but Russia, USA and China have seenincreases of around 0.3, 2.9 and 2.3 GtC respectively. Detailed information on forests and climate change shows that: ● Non-tropical forests have seen an increase in carbon sequestration in recent years, especially in Europe and Eastern Asia, due to conversion of agricultural land and plantations to new forests. ● Forests in industrialised regions are expected to increase by 2050but in the global south, forested areas will decrease. ● Rate of forest loss has decreased from 9.5 million hectares per year in the 1990's to 5.5 million hectares per year in 2010-15. ● The eight countries with the largest forested areas are: Russia, Brazil, China, Canada, USA, DRC, Australia and Indonesia. ● Brazil has the most carbon stored on land and the most extensive deforested area. ● China has the largest amount of afforested area. ● Net Primary Productivity (NPP) refers to the amount of carbon absorbed by forests. For tropical forests it is positive all year round, but deciduous forests, have a negative NPP in winter, but across the whole year their NPP is positive. Milankovitch Cycles Vostok ice core data from Antarctica suggests that in the past temperature change has occurred before carbon dioxide levels have risen, offering a slightly different explanation for historical global warming. It is possible that variations in the Earth’s orbit cause periods of time where we experience a greater heating effect from the sun, increasing the global temperatures. This increase in temperatures causes glaciers to melt and therefore increases flows in the carbon cycle; allowing more CO₂ to enter the atmosphere and for global temperatures to rise further. This is an example of positive feedback. The quantity of freshwater flowing into the oceans increases, causing temperature fluctuations between Earth’s two hemispheres. As the oceans became warmer, they release more CO₂ into the atmosphere (colder water can store more CO₂), causing further global temperature rises. So whilst orbital variations initiated the warming effect, over 90% of warming was likely as a result of the rise in atmospheric CO₂. The results of this study are not widely agreed on, as any slight systematic errors(technical or equipment errors that vary by a consistent amount) in the data collection would affect the overall conclusions of the study. It is thought that it is natural that CO₂levels and temperature increase during interglacial periodsMany. forests colonised areas which became ice free as a result of temperature increases. The causes of present day global warming are more widely agreed upon with 97% of active climate scientists believing that global warming over the last 100 years is very likely to be due to human activity. The International Panel on Climate Change (IPCC) say it is 'virtually certain' that humans are to blame for 'unequivocal' global warming. Source: NASA Impact of the Carbon Cycle on Regional Climates Tropical Rainforests: ● High rates of photosynthesis and respiration in forests lead to greater humidity, cloud cover and precipitation ● Deforestation reduces photosynthesis and respiration, further reducing humidity and cloud cover and decreasing precipitation Oceans: ● Warmer oceans cause more plankton growthand through plankton chemical production, cause cloudsto potentially form. ● Warm oceans also store less CO₂, as carbon sequestration is dependent on a cooler ocean. This means higher temperatures could lessen the effects of oceans as carbon sinks. Note how warmer, equatorial oceans are classed as CO₂ sources. This sets up a positive feedback loop where the greenhouse effect is heightened further. Source: https://serc.carleton.edu/eslabs/carbon/6a.html Feedback Loops A feedback loop is a type of chain reaction, where one process leads to another process, leading to another process, and so on. There are two types of feedback loops: positive and negative. In negative feedback, the process that occurs is counteracted by an opposing process, causing the effects to cancel each other out and nothing to change. In positive feedback, a process occurs, which causes another process to occur, which starts a chain reaction that heightensthe first process. Positive Feedback: ● Wildfires are more likely in hotter and drier climatescreated by global warming, which release large quantities of CO₂ into atmosphere, which in turn then increases the warming effect. ● Ice reflects radiation from the sun, reducing surface warming. As sea temperatures rise and ice melts, the warming effect is amplified as there is less ice to reflect the radiation. Further melting occurs and the process continues. ● Higher temperatures are thawing the permafrost releasing CO₂and methane (which has 20 times the warming effect of CO₂), causing warming on a local and global scale. Permafrost is frozen ground that remains at a temperature of 0°C or lower for at least 2 consecutive years. The higher temperatures cause more permafrost to melt, causing further gas releases and further warming. Negative Feedback: ● Increased photosynthesis by plants and rising global temperatures allows vegetation to grow in new areas, e.g. where permafrost has melted. New vegetation absorbs CO₂ from the atmosphere, decreasing the warming effect ● Higher temperatures and more CO₂ cause a greater carbon fertilisation in plants , so they absorb more CO₂. This reduces the levels of CO₂ in the atmosphere and the rates of warming and carbon fertilisation will decrease. The process repeats. Scientists are now investigating whether carbon fertilisation is affected by other factors and peaks at a certain atmospheric CO₂ level. If this is the case, then there will be a limit to how much CO₂ plants can continue to sequester. It is suggested that carbon fertilisation is limited by water and nitrogen levels. If rainfall decreases as a result of climate change, then carbon fertilisation may decrease as a result, as water is required for photosynthesis. ● Higher CO₂ levels causes phytoplankton to grow (as they feed off CO₂). CO₂ is taken in through photosynthesis and levels decrease as a result, causing phytoplankton to decrease. ● Higher temperatures causes phytoplankton to grow and photosynthesise quicker. Phytoplankton release substances that lead to the formation of clouds, meaning cloud cover increases. Radiation from the sun is therefore less able to reach the oceans, reducing temperatures. This therefore causes phytoplankton to grow less quickly and photosynthesise slower, reducing cloud cover. Land Drainage in Moorland Areas A moorland (also known as peatland) is an expanse of waterlogged, acidic soiland peat (partially decayed organic matter).Waterlogged grounds stops oxygen from permeating, which reduces plant growth. Moorlands are major stores of carbon dioxide ; in fact they are the largest terrestrial carbon store. Many areas of moor/peatland have been drained by large channels, which means they are no longer submerged. They have often been converted into highly productive farmlandor plantations in tropical areas due to their fertile soils. This has caused an increased flood riskin local areas as surface storage is reduced by draining the moorland and streamflow is increased by digging the drainage ditches. This has impacts on the carbon cycle: ● Moor/peatland is drained. ● Water table is lowered affecting flows in the water cycle. ● The dry peat (decayed organic matter and vegetation that is preservedin wetland environments and has high carbon content) degrades easily. ● As the water table lowers, air is able to aid decomposition of the peat, releasing carbon dioxide. ● EU has suggested it will increase its emissions reduction to 30% if major GHG producing countries also improve their targets. National Intervention - Climate Change Act 2008 UK: ● Legally binding target for the UK to reduce GHG emissions by 80% of 1990 levels by 2050 with a target of 26% by 2020 which has recently increased to 34%. ● Created national carbon budgets and the Independent Committee on Climate Change to help the government and report on progress that is being made. ● Improving home insulation. ● Recycling. ● Using energy more wisely and use of smart meters and using public transporter car sharing schemes and calculating personal carbon footprints. Sample Assessment Questions 1. Explain what is meant by stores in relation to carbon cycles. (4 marks) ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ 2. Using Figure 1 analyse the ways in which carbon is stored in oceans. (6 marks) ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ 3. Assess the relative importance of the water cycle in influencing marine carbon processes (20 marks) ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________  The ocean store circulates dissolved carbon dioxide from upper layers to deeper waters. Upwelling currents bring more carbon to the surface than down-welling carbon accounts for. This is because it also brings descending organic carbon to the surface.  A biological store of marine carbon (biota) involves ocean organisms that absorb carbon dioxide from the upper sea as part of photosynthesis (phytoplankton). Others feed on the phytoplankton (zooplankton) giving a biotic release of carbon dioxide to the ocean store from respiration and digestion, but which is a fifth less than has been absorbed.  Waste from these surface organisms, as well as decaying residue sinks to lower levels of the ocean. 90% is carried back to the surface by upwelling currents, while a very small proportion (10%) sinks to the ocean floor as sediments.  Over long periods of time sea bed sediments may become a carbon store in the lithosphere. Despite only a very small proportion of carbon sinking to the sea floor annually, very significant deposits accumulate. Many of these stores change volume rapidly and possibly locally according to ocean and atmospheric conditions (ocean biomass and algal blooms), while others operate on long time- scales and over large spatial scales (ocean floor sediments). 3. Assess the relative importance of the water cycle in influencing marine carbon processes (20 marks) AO1: Knowledge and understanding of processes in the water cycle impacting upon marine carbon processes. AO2: Application of knowledge and understanding to assess the relative importance of factors and processes in the water cycle influencing marine carbon processes. Response should come to a view in relation to the extent of the influence. Notes for answers: AO1  Processes in the water cycle which directly relate to the marine carbon cycle. (river discharge of carbon-rich water into marine environments).  Processes in the marine carbon cycle which do not directly relate to the water cycle. (accumulation of carbon-rich sediments on the sea floor).  Factors which may be changing the influence of the water cycle on marine carbon processes. (changes in rainfall regime).  Global distribution of places where there may be a greater or lesser influence of the water cycle on marine carbon processes.  The role of water in eroding carbon-rich terrestrial rocks and transferring soluble carbon into marine waters. Marine calcification processes and their contribution to marine carbon transfers and stores.  The role of water in increasing the acidity of oceans and the impact on marine calcification processes.  The role of water in coastal eutrophication and influence on algal blooms. The impact of these on ocean carbon processes.  The role of water in causing pollution of marine environments and the impacts on marine organisms and their role in marine carbon processes.  The role of water (through melting ice) in changing the nature of ocean currents and their impact on marine carbon processes. Melting icebergs also release iron and trace elements eroded from the Antarctic/Greenland surfaces causing phytoplankton in their wake to be stimulated, and producing a negative feedback effect on climate change as they absorb CO2.  Case study of a specific marine environment that has been influenced by water-cycle impacts. This may illustrate the scale and spatial distribution of influences as well as temporal duration, degree of permanence and effect on system equilibrium. AO2  Evaluation: Response may argue that the fact that marine environments form much of the hydrosphere and represent the major store of water on earth, then all marine carbon processes are taking place within a key component of the water cycle and could not occur without this store. However, the transfers of water into the store can influence rates, scale and intensity of some marine processes.  Analysis: the water cycle transfers soluble carbonates into the marine system as a result of precipitation falling on to carbon-rich rocks, chemical weathering, and transfer into oceans. But this is dependent upon the distribution of carbon-rich rocks; where surface rocks are composed of non-carbon rich minerals, or are resistant to erosion, there will be limited transfer.  Analysis: atmospheric water vapour combines with CO2 to form carbonic acid, which transfers carbon into marine environments through direct rainfall upon oceans. However, while this may increase the carbon content of oceans it may inhibit calcification as oceans become more acidic and carbonate ions become less accessible to marine organisms. Shell-building by marine organisms is reduced, affecting the transfer of carbon from sea water to organisms to sea bed sediments.  Analysis: river systems can introduce agricultural nutrients into coastal waters stimulating organic growth in the form of algal blooms (eutrophication). The digestion of these phytoplankton by zooplankton can increase the ‘marine snow’ of digested detritus falling to the sea floor. This may feed lower-layer marine life, be carried by currents away from the coasts, or accumulate as carbon-rich sediments on the sea floor. This process is more likely to be limited to coastal areas in regions where there is heavy application of commercial agricultural chemical fertiliser.  Analysis: more intense evaporation of warmer ocean waters in tropical storms can impact marine systems through physical interactions. More intense and frequent hurricanes can disturb sediments and interrupt the metastable equilibrium more frequently. This can be lethal to sensitive marine environments such as coral reefs and disrupt permanently their part in converting soluble carbon to solid forms, disrupting the marine biological carbon sequence.  Evaluation: the duration, degree of permanence/reversibility, and spatial scale of these influences on marine carbon systems should be discussed. The more significant and less significant influences on marine carbon cycles should be considered.  Overall evaluation: More sophisticated responses will recognise that marine carbon processes occur as a carbon sub-system within the larger water cycle that involves oceans as the major store. Changes to the atmospheric carbon cycle are affecting the water cycle, which in turn has specific feedback on marine carbon processes that are becoming more intense as long-term equilibrium in the systems is being disrupted by anthropogenic activity. COASTAL LANDSCAPES AND SYSTEMS 1.1 The coast, and wider littoral zone, has distinctive features and landscapes.  The littoral zone consists of backshore, nearshore and offshore zones, includes a wide variety of coastal types and is a dynamic zone of rapid change.  Coasts can be classified by using longer term criteria such as geology and changes of sea level or shorter term processes such as inputs from rivers, waves and tides.  Rocky coasts (high and low relief) result from resistant geology (to the erosive forces of sea, rain and wind), often in a high energy environment, whereas coastal plain landscapes (sandy and estuarine coasts) are found near areas of low relief and result from supply of sediment from different terrestrial and offshore sources, often in a low-energy environment. 1.2 Geological structure influences the development of coastal landscapes at a variety of scales.  Geological structure is responsible for the formation of concordant and discordant coasts.  Geological structure influences coastal morphology: Dalmatian and Haff type concordant coasts and headlands and bays on discordant coasts.  Geological structure (jointing, dip, faulting, folding) is an important influence on coastal morphology and erosion rates, and also on the formation of cliff profiles and the occurrence of micro-features, e.g. caves. 1.3 Rates of coastal recession and stability depend on lithology and other factors.  Bedrock lithology (igneous, sedimentary, metamorphic) and unconsolidated material geology are important in understanding rates of coastal recession.  Differential erosion of alternating strata in cliffs (permeable/impermeable, resistant/less resistant) produces complex cliff profiles and influences recession rates.  Vegetation is important in stabilising sandy coastlines through dune successional development on sandy coastlines and salt marsh successional development in estuarine areas. 1.4 Marine erosion creates distinctive coastal landforms and contributes to coastal landscapes.  Different wave types (constructive/destructive) influence beach morphology and beach sediment profiles, which vary at a variety of temporal scales from short term (daily) through to longer periods  The importance of erosion processes (hydraulic action, corrosion, abrasion, attrition) and how they are influenced by wave type, size and lithology.  Erosion creates distinctive coastal landforms (wave cut notches, wave cut platforms, cliffs, the cave-arch-stack stump sequence). 1.5 Sediment transport and deposition create distinctive landforms and contribute to coastal landscapes.  Sediment transportation is influenced by the angle of wave attack, tides and currents and the process of longshore drift.  Transportation and deposition processes produce distinctive coastal landforms (beaches, recurved and double spits, offshore bars, barrier beaches and bars, tombolos and cuspate forelands), which can be stabilised by plant succession.  The Sediment Cell concept (sources, transfers and sinks) is important in understanding the coast as a system with both negative and positive feedback, it is an example of dynamic equilibrium. 1.6 Subaerial processes of mass movement and weathering influence coastal landforms and contribute to coastal landscapes.  Weathering (mechanical, chemical, biological) is important in sediment production and influences rates of recession.  Mass movement (blockfall, rotational slumping, landslides) is important on some coasts with weak and/or complex geology.  Mass movement creates distinctive landforms (rotational scars, talus scree slopes, terraced cliff profiles). Integrated Coastal Zone Management (ICZM) - Large sections of coastline (often sediment cells) are managed with one integrated strategy and management occurs between different political boundaries. Impermeable- A rock that does not allow rainwater to pass through. Isostatic- A change in local coastline or land height relative to sea level. Littoral Cell- A section of the coast, within which involves much sediment movement. A littoral cell is not a closed system. Longshore Drift- The transportation of sediment along a beach. Longshore Drift is determined by the direction of the prevailing wind. Low-energy Environment- A coast where wave action is predominantly small constructive waves, causing deposition and leading to beach accretion. Mass Movement - The falling or movement of rock, often due to Gravity. Nearshore- The area before the shore where the wave steepness and breaks before they reach the shore and then reform before breaking on the beach. It extends from the low-tide zone and then out to sea. Permeable- A rock that allows rainwater to pass through it. Plant Succession- Change to a plant community due to growing conditions adapting (eg. sand dunes and salt marshes). Ria- Narrow winding inlet which is deepest at the mouth, formed when sea levels rise causing coastal valleys to flood. Saltation- Smaller sediment bounces along the sea bed, being pushed by currents.The sediment is too heavy to be picked up by the flow of the water. Sediment Cell - Sections of the coast bordered by prominent headlands. Within these sections, the movement of sediment is almost contained and the flows of sediment should act in dynamic equilibrium. Sediment Budget - Use data of inputs, outputs, stores and transfers to assess the gains and losses of sediment within a sediment cell. SMP - Identifies all of the activities, both natural and human which occur within the coastline area of each sediment cell and then recommends a combination of four actions for each stretch of that coastline: Hold the Line, Advance the Line, Managed Realignment and No Active Intervention. Subaerial Processes- The combination of mass movement and weathering that affects the coastal land above sea. Submergent Coast- A coast that is sinking relative to the sea level of the time. Till- Deposits of angular rock fragments in a finer medium. Wave Quarrying- When air is trapped and compressed against a cliff which causes rock fragments to break off the cliff over time. The Coastal System The coast can be considered as an open system as it receives inputs from outside the system and transfers outputs away from the coast and into other systems. These systems may be terrestrial, atmospheric or oceanic and can include the rock, water and carbon cycles. Whilst coasts are open systems, throughout this topic you will be expected to consider the coast as a closed system in some circumstances such as during scientific research and coastline management planning. The coastal system is impacted and impacts upon processes which occur in the five oceans of our planet and the smaller seas of which they are part of. You should be aware of the different habitats and activities which are affected by and affect the coastal environment Sediment Cells Coasts can be split into sections called sediment cells which are often bordered by prominent headlands. Within these sections, the movement of sediment is almost containedand the flows of sediment act in dynamic equilibrium. Dynamic equilibrium refers to the maintenance of a balancein a natural system, despite it being in a constant state of change. The system has a tendency to counteract any changesimposed on the system in order to keep this balance, which is achieved by inputs and outputs constantly changing to maintain the balance. Dynamic equilibrium in a sediment cell is where input and outputs of sediment are in a constant state of change but remain in balance. The dynamic equilibrium may be upset in the long term by human interventions, or in the short term it may be interrupted by natural variations. Within each sediment cell there are smaller subcells. Often the smaller subcells are used when planning coastal management projects. There are many features to the coastal system and most are listed below - there is more detail on each throughout these notes. Most of the questions in your exam will focus on how these features and processes affect the coastal system, though this will not always be explicit in the question title. When you are learning something in this unit, always link it back to the key features below: Inputs: May refer tomaterial or energyinputs. Coastal inputs are not limited to but include three main areas: ● Marine: Waves, Tides, Salt Spray ● Atmosphere:Sun, Air Pressure, Wind Speed and Direction ● Humans:Pollution, Recreation, Settlement, Defences Outputs: May refer to material or energy outputs ● Ocean currents ● Rip tides ● Sediment transfer ● Evaporation Stores/Sinks: Refer to stores and sinks of sediment and material. ● Beaches ● Sand Dunes ● Spits ● Bars and Tombolos ● Headlands and Bays ● Nearshore Sediment ● Cliffs ● Wave-cut Notches ● Wave-cut Platforms ● Caves ● Arches ● Stacks ● Stumps ● Salt Marshes ● Tidal Flats ● Offshore Bands and Bars Transfers/Flows: The processes that link the inputs, outputs and stores in the coastal system: ● Wind-blown sand ● Mass-movement processes ● Longshore drift ● Weathering ● Erosion ○ Hydraulic Action ○ Corrosion ○ Attrition ○ Abrasion ● Transportation ○ Bedload ○ In suspension ○ Traction ○ In solution ● Deposition ○ Gravity Settling ○ Flocculation Energy: The power and driving forcebehind the transfers and flows in the system ● Wind ● Gravitational ● Flowing Water Feedback Loops The coastal system has mechanisms which enhance changes within a system, taking it away from dynamic equilibrium (positive feedback) or mechanisms which balances changes, taking the system back towards equilibrium (negative feedback). Negative feedback loop - this lessens any change which has occured within the system. For example, a storm could erode a large amount of a beach, taking the beach out of dynamic equilibrium as there is a larger input of sediment into the system than output. A negative feedback loop will balance this excess of inputted sediment: ● When the destructive waves from the storm lose their energy excess sediment is deposited as an offshore bar. ● The bar dissipates the waves energy which protects the beach from further erosion. ● Over time the bar gets eroded instead of the beach. ● Once the bar has gone normal conditions ensue and the system goes back to dynamic equilibrium. When the wave moves up the beach, it is known as the swash and when it moves back down the beach into the sea, this is known as the backwash. Factors Affecting Wave Energy Strength of the Wind: Wind is essentially air that moves from an area ofhigh pressure to an area of low pressure. The different pressure areas are caused byvariations in surface heating by the sun. The larger the difference in pressure between two areas (pressure gradient) the stronger the winds. As waves are caused by the wind, stronger winds also mean stronger waves. Duration of the Wind: If thewind is active for longer periods of time, then the energy of the waves will build up and increase. Size of the Fetch: Thefetch is the distance over which the wind blowsand the larger it is, the more powerful the waves will be. It could also be thought of as the distance to the nearest land mass in a particular direction. Wave Types Constructive waves tend to deposit material, which creates depositional landformsand increase the size of beaches. Destructive waves act to remove depositional landformsthrough erosion, which work to decrease the size of a beach. Constructive Destructive Formation Formed by weather systems Localised storm events with that operate in the open ocean stronger winds operating closer to the coast Wavelength Long wavelength Short wavelength Frequency 6-9 Per Minute 11-16 Per Minute Wave Characteristics Low waves, which surge up the High waves, which plunge onto the beach beach Swash Characteristics Strong swash, weak backwash Weak swash, strong backwash Effect on Beach Occurs on gently sloped Occurs on steeply sloped beaches beaches The type of waves in a coastal environment may vary: ● In summer, constructive waves dominate but destructive waves dominate in winter ● Constructive waves may become destructive waves if a storm begins ● Climate change may increase the storm frequency within the UK ● Coastal management may affect the type of waves that occur Negative Feedback: Beaches and Waves The presence of constructive waves causes deposition on the beach, which in turn leads to the beach profile becoming steeper.Steeper beaches favour the formation of destructive waves which are then more likely to occur. The destructive waves erode the beach, reducing the beach profile and leading to the formation of constructive waves. As constructive waves occur more frequently in summer when there are fewer storms, this means that the beach profile is more gentle in summer and steeper during the winter months when destructive waves are more common. This should lead to a state of dynamic equilibrium though in reality this may not occur due to external factors such as the wind strength and direction. Tides Gravity is another key source of energy in coastal environments and is responsible for tides which occur when the gravitational pull of the sun or moon changes the water levels of the seas and oceans. The difference in height between the tides is known as the tidal range and tends to be largest in channels such as river estuaries. The high and low tides and therefore the tidal range are all impacted by the positioning of the moon and the sun. The highest high tide and the lowest low tidesoccur when the sun and the moon are in alignment . Both of their gravitational forces combine to effectively pull the oceans towards them to cause the highest high tides. On the other side of the planet, this creates the lowest possible low tides. This is a spring tide and it creates the largest possible tidal range. The lowest high tide and the highest low tides occur when the sun and the moon are perpendicular to each other. Both of their gravitational forces act against each other, so the overall pull is minimised at high tide, but therefore creates a higher low tide. This is a neap tide and it creates the smallest possible tidal range. Tides affect erosion and lead to the formation of different coastal landforms. Currents Rip currents are powerful underwater currents occurring in areas close to the shoreline on some beaches when plunging waves cause a build up of water at the top of the beach. The backwash is forced under the surface due to resistance from breaking waves, forming an underwater current. This flows away from the shore more quickly due to beach features, such as a gap in a sandbar, creating a rip current. Rip currents claims lives at beaches every year, though it is possible to escape from them by swimming away from them in a direction parallel to the beach. Riptides are different to rip currents as they occur when the ocean tide pulls water through a small area such as a bay or lagoon. Rip currents are an energy source in a coastal environment and can lead to outputs of sediment from the beach area. High-Energy and Low-Energy Coastlines When answering questions in your exam, it is expected that you will include information about the different processes and landforms that may occur in high and low energy environments. High-energy coastlines are associated with more powerful waves, so occur in areas where there is a large fetch. They typically have rocky headlands and landforms and fairly frequent destructive waves. As a result these coastlines are often eroding as the rate of erosion exceeds the rate of deposition. Low-energy coastlines have less powerful waves and occur in sheltered areas where constructive waves prevail and as a result these are often fairly sandy areas. There are landforms of deposition as the rates of deposition exceed the rates of erosion. Wave Refraction Wave refraction is the process by which waves turn and lose energy around a headland on uneven coastlines. The wave energy is focussed on the headlands, creating erosive features in these areas. The energy is dissipated in bays leading to the formation of features associated with lower energy environments such as beaches. Deposition Deposition occurs when sediment becomes too heavy for the water to carry, orif the wave loses energy. Deposition tends to be a gradual and continuous process, so a wave won’t release all its sediment at the same time. This explains why beaches are often either sandy or rocky and these areas are very distinct on the same beach. High-energy coastlines continue to transport smaller sediment, so larger rocks and shingle are deposited in these environments. Low-energy coastlines have much smaller sediment, which is only deposited in these areas where there is a much lower water velocity. As a result, specific landforms of deposition will occur. Two types of deposition are explained below: ● Gravity Settling: The water’s velocity decreasesso sediment begins to be deposited ● Flocculation: This is an important process in salt and tidal marshes. Clay particles clump together due to chemical attraction and then sink due to their high density Weathering and Mass Movement Processes Weathering Weathering is the breakdown of rocks(mechanical, biological or chemical) over time, leading to the transfer of material into the littoral zone, where it becomes an input to sediment cells. Positive Feedback: If the rate of removal of the weathered rock from the base of the cliff is higher than the rate of weathering, then this will promote further weathering as this will increase the area of exposed rock. This will increase the amount of erosion that occurs because this willincrease the supply of rocks which can become part of the erosive processes of saltation and abrasion. Negative Feedback: If the removal of weathered rock from the base of the cliff is slower than the rate of weathering then this will lead to a buildup of debris at the base of the cliff,reducing the exposed cliff area and therefore reducing the rates of weathering. It will also reduce erosion as the cliff foot will be protected from the other forces of erosion. Mechanical (Physical) Weathering: the breakdown of rocks due to exertion of physical forces without any chemical changes taking place ● Freeze-thaw (Frost-Shattering):Water enters cracks in rocks and then the waterfreezes overnight during the winter. As it freezes, water expands by around 10%in volume which increases the pressure acting on a rock, causing cracks to develop. Over time these cracks grow, weakening the cliff making is more vulnerable to other processes of erosion ● Salt Crystallisation:As seawater evaporates, salt is left behind. Salt crystals will grow over time, exerting pressure on the rock, which forces the cracks to widen. Salt can also corrode ferrous (materials that contains iron) rock due to chemical reactions ● Wetting and Drying: Rocks such as clay expand when wetand then contract again when they are drying. The frequent cycles of wetting and dryingat the coast can cause these rocks and cliffs to break up Chemical Weathering: The breakdown of rocks through chemical reactions ● Carbonation: Rainwater absorbs CO2from the air to create a weak carbonic acid which then reacts with calcium carbonate in rocks to form calcium bicarbonatewhich can then be easily dissolved. Acid rain reacts with limestoneto form calcium bicarbonate, which is then easily dissolved allowing erosion ● Oxidation: When minerals become exposed to the air through cracks and fissures, the mineral will become oxidised which will increase its volume(contributing to mechanical weathering), causing the rock to crumble. The most common oxidation within rocks is iron minerals becoming iron oxide, turning the rock rusty orange after being exposed to the air ● Solution: When rock minerals such as rock salt are dissolved Biological Weathering: The breakdown of rocks by organic activity: ● Plant Roots - Roots of plants growing into the cracks of rocks, which exerts pressure, eventually splitting the rocks. Research Angkor Wat for more information on this, even though it is not coastal! ● Birds - Some birds such as Puffins dig burrows into cliffs weakening them and making erosion more likely ● Rock Boring - Many species of clams secrete chemicals that dissolve rocks and piddocks may burrow into the rock face ● Seaweed Acids - Some seaweeds contain pockets of sulphuric acid, which if hit against a rock or cliff face, the acid will dissolve some of the rock’s minerals. (e.g. Kelp) ● Decaying Vegetation - Water that flows through decaying vegetation and then over coastal areas, will be acidic, thus causing chemical weathering Mass Movement Mass movement is the movement of material down a slope under the influence of gravity. Mass movement can be categorised into four main areas: creeps, flows, slides and falls. Mass movement processes act as an input into the littoral zone from the store of the land. The type of mass movement is dependent on: ● Cliff/slope Angle ● Vegetation ● Rock Type ● Saturation of Ground ● Rock Structure ● Presence of Weathering ● The Different Types of Mass Movement are: Soil Creep: The slowest but most continuous form of mass movement involving the movement of soil particles downhill. Particles rise and fall due to wetting and freezingand in a similar way to longshore drift, this causes the soil to move down the slope. It leads to the formation of shallow terracettes. Solifluction:Occurs mainly in tundra areas where the land is frozen (periglacial environments). As the top layers thaw during summer (but the lower layers still stay frozen due to permafrost) the surface layers flow over the frozen layers. Forms solifluction lobes. Mudflows: An increase in the water content of soil can reduce friction, leading to earth and mud to flow over underlying bedrock, or slippery materials such as clay. Water can get trapped within the rock increasing pore water pressure, which forces rock particles apart and therefore weakens the slope. Pore Water Pressure (PWP)is an important energy source for determining slope stability and refers to the pressure of groundwater held within soil or rock. Mudflows represent a serious threat to life as they can be very fast flowing. Rockfall: Occurs on sloped cliffs (over 40o) when exposed to mechanical weathering, though mostly occurs on vertical cliff faces and can be triggered by earthquakes. It leads to scree (rock fragments) building up at the base of the slope. Scree is a temporal store which acts as an input to the coastal zone. Landslide: Heavy rainfall leads towater between joints and bedding planes in cliffs (which are parallel to the cliff face) which canreduce friction and lead to a landslide. It occurs when a block of intact rock moves down the cliff face very quickly along a flat slope. Can be very dangerous. Landslip or Slump: Contrary to a landslide, theslope is curved, so often occur in weak and unconsolidated clay and sands areas. A build up in pore water pressure leads to the land to collapse under its own weight. This can create a scarred/terracedappearance to the cliff face. Runoff: Runoff is an example of a link between the water cycle and the coastal system, as the water in the form of overland flow may erode the clifface and coastal area or pick up sediment, that then enters the littoral zone, when it is transported in the water via suspension. It may also be responsible for increasing pollution in coastal areas if it picks up waste or excess chemicals. Vulnerability to Sub-Aerial Processes Temperature and climate can influence the prominence of weathering. In colder climates, mechanical weathering is more common, whereas in warmer climates, chemical weathering is more common. Coastal Landforms and Landscapes of Erosion Caves, Arches, Stacks & Stumps This sequence occurs on pinnacle headlands: ● Initially, faults in the headland are eroded by hydraulic action and abrasion to create small caves ● The overlying rock in a cave may collapse, forming ablowhole. The blowhole spurts water when a wave enters at the base, forcing sea spray and air out of the top ● Marine erosion widens faults in the base of the headland, widening over time to create a cave ● The cave will widen due to both marine erosion and sub-aerial processes, eroding through to the other side of the headland, creating an arch ● The arch continues to widen until it is unable to support itself, falling under its own weight through mass movement, leaving a stack as one side of the arch becomes detached from the mainland ● This was seen recently at the Azure Window in Malta. With marine erosion attacking the base of the stack, eventually the stack will collapse into a stump ● A wave-cut platform will be left afterwards Cliff Profile and Rate of Retreat Steep Cliffs: Most common where the rock is strong and fairly resistant to erosion. Sedimentary rocks that have vertical strata are also more resistant to erosion, creating steep cliffs. An absence of a beach, long-fetch and high energy waves also promote steep cliff development. Most commonly found in high-energy environments Gentle Cliffs: Most commonly found in areas with weaker rocks which are less resistant to erosion and are prone to slumping. Low-energy waves and a short fetch will lead to the formation of a scree mound at the base of the cliff, reducing the overall cliff angle. A large beach would also reduce wave energy and prevent the development of steep cliffs by reducing erosion rates. Most commonly found in low-energy environments Rate of Retreat: Dependent on the relative importance of marine factors(fetch, beach, wave energy) and terrestrial factors(subaerial processes, geology, rock strength). The cliff’s most likely to retreat are those that are made of unconsolidated rockand sands. Negative feedback mechanisms can help to protect and restore a coast. For example, during a storm, part of a cliff may collapse so the material produced will protect the base of the cliff from marine erosion, reducing further cliff recession. Alternatively, sand dunes may be eroded during a storm, meaning a loss of a sediment on land. However, the sediment produced may be deposited in offshore bars, which protect the coastline from further erosion by dissipating wave energy. Wave-cut Notch and Platform This sequence occurs at steep cliffs: ● When waves erode a cliff, the erosion is mostly concentrated around the high-tide line. The main processes of hydraulic action and corrasion create a wave-cut notch ● As the notch becomes deeper (and sub-aerial weathering weakens the cliff from the top) the cliff face becomes unstable and falls under its own weight through mass movement ● This leaves behind a platform of the unaffected cliff base beneath the wave-cut notch ● Over time the same processes repeat leading to a wave-cut platform to be formed, which is normally exposed at high-tide Vegetation helps to stabilise coastal sediment in many ways: ● Roots of plants bind soil together which helps to reduce erosion ● When completely submerged, plants provide a protective layer for the ground and so the ground is less easily eroded ● Plants reduce the wind speedat the surface and so less wind erosion occurs Sand Dunes Sand dunes occur when prevailing winds blow sediment to the back of the beach and therefore the formation of dunes requires large quantities of sand and a large tidal range. This allows the sand to dry, so that it is light enough to be picked up and carried by the wind to the back of the beach. Frequent and strong onshore winds are also necessary. The dunes develop as a process of a vegetation succession: ● Pioneer species such as sea rocket are resistant and able to survive in the salty sand, with its roots helping to bind the dunes together ● Decaying organic matter adds nutrients and humus (organic material comprised of decaying plant and animal matter) to the soil allowing marram grass to grow ● Larger plants are able to colonise the area and the climatic climax occurs when trees are able to colonise the area This leads to a dune structure involving different types of dunes: ● Embryo Dunes – Upper beach area where sand starts to accumulate around a small obstacle (driftwood, wooden peg, ridge of shingle) ● Yellow Dunes – As more sand accumulates and the dune grows, vegetation may develop on the upper and back dune surfaces, which stabilises the dune. The tallest of the dune succession ● Grey Dunes – Sand develops into soil with lots of moisture and nutrients, as vegetation dies, enabling more varied plant growth ● Dune Slack – The water table rises closer to the surface, or water is trapped between hollows between dunes during storms, allowing the development of moisture-loving plants (e.g. willow grass) ● Heath and Woodland – Sandy soils develop as there is a greater nutrients content, allowing for less brackish plants to thrive. Trees will also grow (willow, birch, oak trees) with the coastal woodland becoming a natural windbreak to the mainland behind Estuarine Mudflats and Saltmarshes Deposition occurs in river estuaries because when the flow of water from the river meets with the incoming tides and waves from the sea, causing water flow to virtually cease, so the water can no longer carry its sediment in suspension. They may also occur in sheltered areas such as behind a spit or other areas where there are no strong tides or currents to prevent sediment deposition and accumulation. As most of the sediment is small, this leads to a build up of mud, which over time builds up until it is above the water level. Deposition occurs as a result of flocculation. Pioneer plants colonise this area, leading to more sediment becoming trapped. This colonises the transition zone between high and low tide. A meadow is formed as sections of the salt marsh rise above the high tide level, leading to the climatic climax of the vegetation succession when trees begin to colonise the area. Stability of Depositional Landforms Depositional landforms consist of unconsolidated sediment making them vulnerable to change. During major storms large amounts of sediment can be eroded or transported elsewhere, removing a landform from one region of the sediment cell. Depositional landforms rely on a continuous supply of sediment to balance erosion, which may see some landforms changed as their dynamic equilibrium shifts. Sea Level Change Sea levels change in short-term period such as day-to-day or minute to minute due to factors such as high tide and low tide,wind strength and changes in wind direction or changes in atmospheric pressure (the lower the pressure, the higher the sea levels). Sea level change also occurs over long-term periods, leading to the formation of various coastal landforms as a result of the following processes: Isostatic Change Isostatic change occurs when the land rises or falls relative to the sea and is a localised change. Isostatic sea level change is often a result ofisostatic subsidence(glaciers weigh down the land beneath, and so the land subsides). When the glaciers melted, this has lead to isostatic recovery and the coastline to rebound and rise again in the areas that were covered by ice. In the UK, this has caused a see-saw effect. Scotland and the north-west of England are rising at around 1.5mm per year as they were previously covered by glaciers, but this has caused the land in the south-east to subside around 1mm a year. This links into water and carbon cycles and glaciation units. In some areas of the Mediterranean, some historical ports have been submerged and other raised above the current sea level as a result of this process Tectonic activity (such as earthquakes and volcanic eruptions) may cause land subsidence, therefore causing isostatic sea level change. This was seen in the 2004 Indian Ocean earthquake, which caused the city of Bandeh Aceh to sink permanently by 0.5m. (This links to the Hazards section of Geography). Eustatic Change Eustatic change affects sea level across the whole planet. You can remember this usingEustatic affects Everywhere. Eustatic change may be due tothermal expansion/contraction or changes in glacial processes. Thermal expansion is the process of water expanding when it gets warmer, and so the volume of water increases leading to rising sea levels. In the last ice age, sea levels were over 100m lower than they are currently due as the water was stored in large ice caps as the majority of precipitation fell as snow. When the ice caps melted, this lead to rising sea levels. As a result of global warming, both processes are acting to increase sea levels with the IPCC predicting sea level increases for 0.3m - 1.0m by 2100. In Miami, they are currently facing significant problems, with much of the coastal strip flooding regularly during high tides as a result of rising sea levels. Emergent Coastal Landforms Where the land has been raised in relation to the coastline, landforms such as arches, stacks and stumps may be preserved. Raised beaches are common before cliffs which are also raised (relic cliffs), with wave-cut notches and similar features proof of historical marine erosion. Submergent Coastal Landforms Landforms of submergence occur when the sea level rises or the coastline sinks in relation to the sea. An easy way to imagine the effects of rising sea levels is to picture a mountainous area close to the coast and then imagine sea level rising by around 100m leading to some of the valley’s being flooded. Rising sea levels leads to the following landforms: Rias: Rias are formed when rising sea levelsflood narrow winding inlets and river valleys. They are deeper at the mouth of the inlet, with the water depth decreasing further inland. Fjords: Fjords are formed when rising sea levels flood deep glacial valleys to create natural inlets and harbours. Fjords can be found across the world though in some countries such as New Zealand they may be referred to as sounds. They are deeper in the middle section than they are at the mouth, with the shallower section identifying where the glacier left the valley. Dalmatian Coasts: This type of coastline occurs whenvalleys running parallel to the coast become flooded as a result of sea level change. This leaves a series of narrow, long and rugged islands and the best examples can be seen in Croatia. They may also be referred to as Pacific coasts. Contemporary Sea Level Change Since records began around 20,000 years ago, sea levels have always been rising from 120m below the levels which they are now at today. The graph clearly shows that sea level increase slowed around 8,000 years ago, andlevelled at the current height around 3000 years ago. Since 1880 and the industrial revolution, sea levels have increased by around 235mm. That may not sound significant, but it is enough to overwhelm some sea defences, whencombined with higher than expected storm surges. It also affects the drainage system in coastal cities increasing the flooding risk. The International Panel on Climate Change (IPCC) predicts that sea levels may rise between 0.3 - 1.0m by 2100 and the graph shown on the left shows the different models and climate predictions that they have created. This could cause aquifers to be polluted in low-lying atoll islands (coral reefs protruding from the sea) affecting the residents who live in them. It may also inundate many coastal cities and significantly increase the risks from tropical storms and Tsunamis. In some areas turning the coastal area into recreational land as a method of adaptation to climate change is proving to be a popular option. Risks to Coastal Environments Coastalisation is the process by which the coast is being developed and people are moving to the coast, increasing the number of people at risk from marine related environmental activity. It may be a by-product of urbanisation in which people are moving to cities as the majority of large cities are coastal. This is not a required term for the specification, but may be useful to include when discussing the risks of sea level change in future. Storm Surges A storm surge is a result of the low pressure created by large weather events such as tropical storms. It raises the sea level and therefore poses a significant flooding risk as it has the potential to inundate flood defences, making the other impacts of a tropical storm more potent. The risk from a storm surge may be exacerbated by: ● Removing Natural Vegetation: Mangrove forests are the most productive and complex ecosystem in the world. Mangroves also provide protection against extreme weather events such as cyclones which are very common in the Bay of Bengal. However, due to pressure for land space, many mangrove forests are destroyed to make space for tourism, local industry, or housing. Mangroves are an excellent method of coastal management as they can also keep up with global sea level rises of up to eight times the current rate. Theytrap sediment leading to accretion on the coastline, helping protect communities from the potential impacts of climate change ● Global Warming: As the surface of oceans get warmer, it ispredicted that the frequency and intensity of storms will increase, and so the severity of storm surges and flooding is also expected to increase - there is no agreed scientific consensus Consequences for Communities Some areas of the coast may have significantly reduced house and land prices(as the area becomes known to be at significant risk) leading to economic loss for homeowners and local coastal economies. In the UK, many insurers don’t provide home insurance to people living along coastlines that are at extreme risk of erosion or storm surges. Storm surges also damage the environment by destroying plant successions and damaging many coastal landforms. Depositional landforms, due to theirunconsolidated nature, may potentially be destroyed as was seen in 2013, when the spit ‘Spurn Head’ was partially destroyed by a large storm surge. If depositional features are destroyed then erosion may occur more quickly closer to the cliff face, which can increase the risk of collapse of cliffs and threats to land owners. Cost-Benefit Analysis (CBA) This is an analysis that is carried out before any form of coastal management takes place. The expected cost of the construction, demolition, maintenance etc. of a coastal management plan is then compared to the expected benefits of a scheme which may include the value of land, homes and businesses that will be protected. Cost and benefits may be tangible (monetary value) or intangible (other effects such as visual impact). According to DEFRA’s1:1 analysis, the expected benefits have to out way the costs for a project to go ahead. Sustainable Coastal Management As the negative impacts of many coastal management schemes have become clear, sustainable integrated approaches are becoming more widely used. It is key that you have a good understanding of these methods as they are a topic that you may include in 20 mark question answers. They are holistic strategies, meaning that it is recognised that all of the different sections of the coastline are interlinked and function together as a whole. Smaller sections are not considered separately, unlike with traditional methods. Aspects of managing coast in a sustainable way include: ● Managing natural resources like fish, water, farmland to ensure long term productivity ● Ensuring that there are new jobsfor people who may face unemployment as a result of protection measures. E.g. if a decision is taken that fishing needs to decrease as currently it is above sustainable levels ● Educating communities about the need to adapt and how to protect the coastline for future generations ● Monitoring coastal changes and then using adaptation or mitigation as a response to the observed changes ● Ensure that everybody is considered when changes are proposed and then adopted Integrated Coastal Zone Management (ICZM) ICZM is one method of sustainable coastline management. Large sections of coastline (often sediment cells) are managed with one integrated strategy. Management occursbetween different political boundaries, which is both beneficial and problematic as decision making is likely to be a longer process. In the UK, different councils will have to work and manage coasts together: ● The ICZM recognises the importance of the coast for people’s livelihoods ● The ICZM recognises that coastal management must be sustainable whereby economic development is important, but is not prioritised over protection of the coastal environment ● The ICZM must involve all stakeholders, plan for the long term and try to work with natural process and not against them ● It recognises that sediment eroded in one location may form a protective beach elsewhere and therefore a decision to protect one coastal community may not outweigh the disadvantages of exposing another community to increased erosion ● In 2013 the EU adopted a new initiative which promotes the use of ICZM’s across all of Europe’s coastlines, which recognised the benefits of the ICZM strategy Shoreline Management Plans (SMPs) For each sediment cell in the UK, an SMP has been created to help with coastline management. Each SMP identifies all of the activities, both natural and human which occur within the coastline area of each sediment cell. The sediment cells are considered to be closed for the purposes of management, although in reality there will be some exchanges between the different sediment cells. SMP’s are recommended for all sections of English and Welsh coastlines by DEFRA (governing body responsible for majority of environmental protection in the UK). Four options are considered for each stretch of the coastline: ● Hold the Line: Defences are used to maintain the current position of the shoreline ● Managed Realignment/Retreat: Defences and engineering techniques are used to allow the coastline to advance inland and create its own natural defences such as salt marshes ● Advance the Line: Defence are built to try and move the shoreline seawards, potentially to protect an important population centre or tourist amenity ● No Active Intervention: The coastline is exposed to natural processes Different factors are considered when choosing a management option: ● Economic value of assets that could be protected. A known area of gas reserves may be protected, though a caravan park may not be ● The technical feasibility of engineering solutions. A sea wall may not be possible for a certain location ● The ecological and cultural value of land. For example, it may be desirable to protect historic areas and Sites of Special Scientific Interest (SSSI) Conflict Over Policy Decisions When considering coastal management their may be winners and losers. Winners can be classified as those who benefit economically(e.g. their homes and businesses are protected), environmentally (e.g. habitats are protected) and socially(community ties still remain in place, people still have jobs so less stress and worrying). Losers can be classified as those who lose their property, lose a job, or have to relocate elsewhere. Communities and homeowners have a strong attachment to a place so losing their properties and their social networks is a great loss. This will make them financially worse offand many people may feel lonely if forced to move and may be angered if areas are not chosen to be protected. Business owners may be angered if nothing is done to protect the area in which they have their business, which could cause them to lose profitability and regular clients. DEFRA funding has been reduced by the central government since 2010 so they cannot invest in coastal management in all areas and now have to prioritise their funding in the most important locations. Some people may feel aggrieved by this. The Impact of Coastal Management on Sediment Cells Coastal management has a variety of impacts on sediment cells and any form of intervention will cause some kind of impact. Installing a sea wall would reflect wave energy downdrift increasing wave energy and erosion elsewhere on the coastline. Less erosion occurs in these areas with the sea wall, so there is alsoless sediment in the areas with increased wave energy.Less sediment reduces the beach size, so the cliff is more exposed to erosion from the higher energy waves. Building groynes has the same effect on downdrift areas as longshore drift can no longer transport sediment away from one stretch of coastline. Coastal Management Examples There are many different management strategies used by national governments to reduce erosion, stop coastline recession or to increase their beach. However, some strategies are more successful than others and not all strategies are sustainable. US East Coast Barrier Islands Characteristics ● The East coast of the USA is dominated by barrier islands. These barrier islands can be found from Florida in the South all the way up to Connecticut in the North. ● Made of sand, there are 23 shifting barrier islands which each create lagoons behind them. ● There is currently ongoing debate about how these islands have formed. Conservation ● Barrier islands are a form of defence as they dissipate wave energy and lead to waves breaking further out and so the waves hitting land are less destructive. Since the East Coast is repeatedly hit by hurricanes (forming in the Atlantic Ocean), the barrier islands are an important natural defence against storm surges. ● Most islands are open for low-impact tourism activities – hiking, fishing, bird watching. However, many restrictions are put into place to protect the nesting birds and shellfish. ● No permanent residence is permitted on the barrier islands. A previous beach resort and settlements have all been washed away, due to the shifting nature of the barrier islands. Tuvalu Tuvalu is a low-lying Pacific Island, which is becoming increasingly vulnerable as eustatic sea level rise continues. Most areas in Tuvalu are only 1-2m above sea level with the highest point only 4.5m above sea level. Its population have had to mitigate to the changing coastal environment or forced to migrate to New Zealand. Problems & Mitigation Solutions ● More tropical cyclones are occurring, due to an increase in sea temperatures  Residents must construct cyclone shelters to avoid injury ● Flooding of low-lying settlements has resulted in the drowning of cattle  Farmers are forced to move further inland. May consider importing food to avoid hunger. ● Salt water encroachment has led to crop failures and loss of local water sources  Residents grow staple crops in concrete plots and must travel further inland to access a freshwater supply to drink from and water their crops. Migration Some cannot afford to mitigate or are fed up of losing cattle, crops and economic assets. Therefore, there is a growing number of environmental refugees from Tuvalu who must live in New Zealand to survive. This can result in a better standard of living, but cultural tensions can arise between the migrants and locals. Mark schemes 1. Explain how the sediment cell concept contributes to the understanding of coastal systems (9 marks) Note for answer The indicative content below is not prescriptive and candidates are not required to include all of it. Other relevant material not suggested below must also be credited. Relevant points may include: • the processes of erosion, transportation and deposition within the coastal margin is largely contained in sediment cells or littoral cells so coastal systems are largely self-contained • there are both onshore and offshore processes which contribute to the sediment cells, influencing the size of store • there are 11 large sediment cells in England and Wales • a sediment cell is generally thought to be a closed system, which suggests that no sediment is transferred from one cell to another • the boundaries of sediment cells are determined by the topography and shape of the coastline, with a major role played by peninsulas • these act as natural barriers that prevent the transfer of sediment from one cell to another • in reality, however, it is unlikely that sediment cells are fully closed with variations in wind direction and tidal currents, meaning that there is some transfer between cells. Fine material is most likely to be transported between sediment cells • there are also many sub-cells of a smaller scale existing within the major cells. 2. Evaluate the contribution that changes in sea level make to the formation of coastal landscapes (9 marks). Notes for answers The indicative content below is not prescriptive and candidates are not required to include all of it. Other relevant material not suggested below must also be credited. Relevant points may include: AO1 • coastal landscapes are made up of an assemblage of landforms that have developed over time – some in the short term, e.g. beach cusps, some over a much longer term, e.g. headland and bays • coastal landscapes are affected by the nature of the coastline before sea-level change, e.g. whether it is glaciated or not, which will affect the rate of erosion and deposition • the topography of the coastline is important – steep as opposed to low-lying coastal regions • the disposition of rocks, concordant or discordant, will affect the development of particular landforms • the direction of sea-level change (i.e. positive or negative) will have significant impact on the type of landscape that develops AO2 • submergence of coasts results from a relative rise in sea level and results is a variety of flooded valleys changing the shape and form of coastlines and, inevitably the landforms • emergence of coasts results from a relative fall in sea level, resulting in a variety of features such as offshore bars, raised beaches and fossil cliff lines. • coastal landscapes are a consequence of a complex history of relative change so both emergent and submerged features can be found in the same areas, e.g. Scotland with fjords and raised beaches • sea-level change is both short term and long term with short-term changes involving a tidal range, e.g. between spring and neap tides, that has a significant impact on landform formation. Short-term sea-level changes create daily changes to some coastal landforms, especially beaches • storm surges will also increase sea levels in the short term and have a significant impact on the creation of landforms, which can be dramatic, e.g. Hurricane Katrina • longer-term changes are a result of a complex combination of eustatic, isostatic and sometimes tectonic movements which result in landscape changes, e.g. post-glacial sea-level rise • sea-level changes both short term and long term suggest that coastal landforms are in dynamic equilibrium with the processes that create them. HAZARDS 1.1 The global distribution of tectonic hazards can be explained by plate boundary and other tectonic processes.  The global distribution and causes of earthquakes, volcanic eruptions and tsunamis.  The distribution of plate boundaries resulting from divergent, convergent and conservative plate movements (oceanic, continental and combined situations).  The causes of intra-plate earthquakes, and volcanoes associated with hot spots from mantle plumes. 1.2 There are theoretical frameworks that attempt to explain plate movements.  The theory of plate tectonics and its key elements (the earth’s internal structure, mantle convection, palaeomagnetism and sea floor spreading, subduction and slab pull).  The operation of these processes at different plate margins (destructive, constructive, collision and transform).  Physical processes impact on the magnitude and type of volcanic eruption, and earthquake magnitude and focal depth (Benioff zone). 1.3 Physical processes explain the causes of hazards  Earthquake waves (P, S and L waves) cause crustal fracturing, ground shaking and secondary hazards (liquefaction and landslides).  Volcanoes cause lava flows, pyroclastic flows, ash falls, gas eruptions, and secondary hazards (lahars, jökulhlaup).  Tsunamis can be caused by sub-marine earthquakes at subduction zones as a result of sea- bed and water column displacement.  Tropical storms are caused by warm seas, the Coriolis effect and low shear pressure and can cause storm surges, coastal flooding, high winds and landslides.  Wildfires are caused by natural and human factors including lightning strike and arson. 1.4 Disaster occurrence can be explained by the relationship between hazards, vulnerability, resilience and disaster.  Definition of a natural hazard and a disaster, the importance of vulnerability and a community’s threshold for resilience, the hazard risk equation.  The Pressure and Release model (PAR) and the complex inter-relationships between the hazard and its wider context.  The social and economic impacts of tectonic hazards (volcanic eruptions, earthquakes and tsunamis) on the people, economy and environment of contrasting locations in the developed, emerging and developing world. 1.5 Hazard profiles are important to an understanding of contrasting hazard impacts, vulnerability and resilience.  The magnitude and intensity of hazards is measured using different scales (Mercalli, Moment Magnitude Scale (MMS), Volcanic Explosivity Index (VEI) and Saffir Simpson Scale).  Comparing the characteristics of earthquakes, volcanoes, tsunamis, storms and wildfires (magnitude, speed of onset and areal extent, duration, frequency, spatial predictability) through hazard profiles.  Profiles of earthquake, volcano, tsunami, storm and wildfire events showing the severity of social and economic impact in developed, emerging and developing countries. 1.6 Development and governance are important in understanding disaster impact and vulnerability and resilience.  Inequality of access to education, housing, healthcare and income opportunities can influence vulnerability and resilience.  Governance (P: local and national government) and geographical factors (population density, isolation and accessibility, degree of urbanisation) influence vulnerability and a community’s resilience.  Contrasting hazard events in developed, emerging and developing countries to show the interaction of physical factors and the significance of context in influencing the scale of disaster. 1.7 Understanding the complex trends and patterns for disasters helps explain differential impacts.  Tectonic disaster trends since 1960 (number of deaths, numbers affected, level of economic damage) in the context of overall disaster trends. (6); research into the accuracy and reliability of the data to interpret complex trends  Tectonic mega-disasters can have regional or even global significance in terms of economic and human impacts. (ü 2004 Asian tsunami, 2010 Eyafjallajokull eruption in Iceland (global independence) and 2011 Japanese tsunami (energy policy))  The concept of a multiple-hazard zone and how linked hydrometeorological hazards sometimes contribute to a tectonic disaster (the Philippines). 1.8 Theoretical frameworks can be used to understand the predication, impact and management of hazards.  Prediction and forecasting (P: role of scientists) accuracy depend on the type and location of the tectonic hazard.  The importance of different stages in the hazard management cycle (response, recovery, mitigation, preparedness). (P: role of emergency planners)  Use of Park’s Model to compare the response curve of hazard events, comparing areas at different stages of development. 1.9 Hazard impacts can be managed by a variety of mitigation and adaptation strategies, which vary in their effectiveness.  Strategies to modify the event include land-use zoning, hazard – resistant design and engineering defences as well as diversion of lava flows. (P: role of planners, engineers)  Strategies to modify vulnerability and resilience include hi-tech monitoring, prediction, education, community preparedness and adaptation. (F: models forecasting disaster impacts with and without modification).  Strategies to modify loss include emergency, short and longer term aid and insurance (P: role of NGOs and insurers) and the actions of affected communities themselves. Hazards Glossary - AQA Geography A-Level Accretion Wedge- The accumulation of material at the point of subduction. Aseismic Buildings- Buildings designed to withstand or minimise destruction during an earthquake. Asthenosphere- The upper mantle layer of the Earth. It is semi-molten and approximately 2000km wide. Ash- Fine particles and dust ejected during an eruption, which can remain airborne as clouds or accumulate on the ground. Continental Crust- Crust that forms the continents of the lithosphere, on average 35km thick. Continental Drift- The movement of tectonic plates, due to varying weights of crust. It was originally thought that convection currents caused the movement of the plates, but now slab pull is thought of as the primary driving force. Controlled Burning- Intentionally burning vegetation with the aim of reducing fuel available for a wildfire and disrupting the fire’s path. Convection Currents- The circulation of magma within the mantle (asthenosphere). Magma is heated by radioactive processes in the core and cools at the surface, and so circulates between the two places. Coriolis Effect- The Earth’s spin affects the movement of air masses and winds, depending on a location’s latitude. Crown Fires- Wildfires that burn the entirety of a tree (from top to bottom), often the most destructive and dangerous type of wildfire. Degg’s Model- This model shows that a hazard becomes a disaster if it affects a vulnerable population. Epicentre– The point on the surface, directly above the earthquake's origin. Natural Hazard in Human Ecological Perspective: Hypotheses and Models, 1971. Education -A person who is more educated about hazards may understand their full effects on people and how devastating they can be and have been in the past. Those who are less educated may not understand the full extent of a hazard and may not evacuate etc. Religion and beliefs - Some may view hazards as put there by God for a reason, or being part of the natural cycle of life etc. so may not perceive them to be negative. In contrast, those who believe strongly in environmental conservation may perceive hazards to be a huge risk to the natural environment, especially hazards that are becoming more frequent due to global warming. Mobility - Those who havelimited access to escape a hazard may perceive hazards to be greater threats than they are. Whether they are in a secluded location, or if they are impaired with a disabilityor illness, those who cannot easily leave an area quickly may feel more at risk. Human Responses to Hazards Hazards can be responded to in a passive way (making no effort to lessen a hazard) or in an active way. Fatalism is a passive response to a hazard. ● Fatalism: The viewpoint that hazards are uncontrollable natural events, and any losses should be accepted as there is nothing that can be done to stop them. Active responses to hazards are any strategy used to overall contribute to a lower hazard risk. ● Prediction: Usingscientific research and past events in order to know when a hazard will take place, so that warnings may be delivered and impacts of the hazard can be reduced . In some cases, hazards may also beprevented when predicted early enough (e.g. predicting wildfires from climatic red flags). ● Adaptation: Attempting to live with hazards by adjusting lifestyle choices so that vulnerability to the hazard is lessened (e.g. earthquake proof houses). ● Mitigation: Strategies carried out to lessen the severity of a hazard (e.g. sandbags to offset impact of flooding). ● Management: Coordinated strategies to reduce a hazard’s effects. This includes prediction, adaptation, mitigation. ● Risk sharing: A form ofcommunity preparedness, whereby the community shares the risk posed by a natural hazard and invests collectively to mitigate the impacts of future hazards New Zealand is an example of where risk sharing has worked. As a multi-hazard environment, New Zealand is under threat from earthquakes, tsunamis, volcanoes, and weather-related hazards. The cost of these hazards are huge; the Canterbury Earthquake (2010) alone cost the country 20% of it’s national GDP. There are now attempts to share the risk by insurance investment, so strategies can be put in place before the disasters rather than investing more in a clean up. Aspects of Hazards and How They Affect Human Responses Every hazardous event varies in terms of its location, frequency, and strength. These aspects of a natural event create different types of hazards, and influence how people respond to these hazards. Incidence: Frequency of a hazard. This is not affected by the strength of a hazard, it is just how often a hazard occurs. Low incidence hazards may beharder to predict and have less management strategies put in place, meaning the hazard could be more catastrophic when it does eventually occur. Also, low incidence hazards are usually (but not always) more intense than high incidence hazards. For example, there are only 36 recorded earthquakessince 1500 that were a magnitude of 8.5 or higher, but millions of earthquakes that are too weak to be recorded are thought to happen every year. Distribution: where hazards occur geographically. Areas of high hazard distribution are likely to have a lot of management strategies, and those living there will be adapted to the hazardous landscape because it dominates the area more so than in places with low hazard distribution. Intensity:the power of a hazard i.e. how strong it is and how damaging the effects are Magnitude: the size of the hazard, usually this is how a hazard’s intensity is measured High magnitude,high intensity hazards will haveworse effects, meaning they will require more management, e.g. more mitigation strategies will be needed to lessen the effects and ensure a relatively normal life can be carried out after the hazard. Magnitude and intensity are not interchangeable terms and it is important that this is recognised. The magnitude is usually definable and can be a number- this does not change. Intensity, however, is the effects on the person, and can change dependent on the distance from the hazard or the management strategies combating high magnitude risks. An effective way to remember this is through a television broadcast analogy. The magnitude is the signal being sent outand the frequency of the television transmission; the intensity is how well it is being received by the person. Even if the quality (intensity) on your end is poor and grainy, the broadcast (magnitude) is always going to be on the same frequency. Level of development: economic development will affect how a place can respond to a hazard, so a hazard of the same magnitude may have very different effects in two places of contrasting levels of development. Even if the hazard is identical, an area with a lower level of development is less likely to have effective mitigation strategies as these are costly. Therefore, the effects of a hazardous event is likely to be much more catastrophic in a less economically developed area. However, there are many high income countries that are not as prepared for natural hazards as they should be, meaning they lack the management strategies for an event. This is especially true in multi-hazard environments where resources are spread thinly over a variety of hazards. In Canada where wildfires have been increasing over the last few years (as a result of climate change), less money and resources have been available for earthquake and tsunami preparation . Even detailed evacuation routes and tsunami sirens are not available in popular tourist beaches such as Vancouver Island or Pacific Rim National Park. Text message systems are available to act as a warning system to suggest people to evacuate, but many people switch their phones off at night, reducing the effectiveness. Overall, level of development may not have the biggest part to play in a hazard, and it is more to do with how these countries use their development for mitigation. The Park Model The Park Model is a graphical representation of human responses to hazards. The model shows the steps carried out in the recovery after a hazard, giving a rough indication of time frame. ● The steepness of the curve shows how quickly an area deteriorates and recovers. ● The depth of the curve shows the scale of the disaster(i.e. lower the curve, lower the quality of life). The Park Model of Human Response to Hazards Stage 1 - Relief Stage 2 - Rehabilitation Stage 3 - Reconstruction (hours-days) (days-weeks) (weeks-years) ● Immediate local ● Services begin to be ● Restoring the area to response - medical restored the same or better aid, search and rescue ● Temporary shelters quality of life ● Immediate appeal for and hospitals set up ● Area back to normal - foreign aid - the ● Food and water ecosystem restored, beginnings of global distributed crops regrown response ● Coordinated foreign ● Infrastructure rebuilt aid - peacekeeping ● Mitigation efforts for forces etc. future event The model also works as a control line to compare hazards. An extremely catastrophic hazard would have a steeper curve than the average and would have a slower recovery time than the average, for example. This has been indicated by the blue line. These plates move due to the convection currents in the asthenosphere, which push and pull the plates in different directions. Convection currents are caused when the less dense magma rises, cools, then sinks. The edges of where plates meet are called plate boundaries (or plate margins). Different Plate Boundaries At plate boundaries, different plates can either move towards each other (destructive plate margin),away from each other (constructive plate margin), or parallel to each other (conservative plate margin). Different landforms are created in these different interactions. This spider diagram outlines what landforms and processes occur at the boundaries. Destructive plate boundaries Continental and oceanic: ● Denser oceanic plate subducts below the continental. ● The plate subducting leaves a deep ocean trench. ● Fold mountains occur when sediment is pushed upwards during subduction. ● The oceanic crust is melted as it subducts into the asthenosphere. ● The extra magma created causes pressure to build up. ● Pressurised magma forces through weak areas in the continental plate ● Explosive, high pressure volcanoes erupt through the continental plate, known as composite volcanoes. Oceanic and oceanic: ● Heavier plate subducts leaving an ocean trench. Fold mountains will also occur. ● Built up pressure causes underwater volcanoes bursting through oceanic plate. ● lava cools and creates new land called island arcs. Continental and continental: ● Both plates are not as dense as oceanic so lots of pressure builds. ● Ancient oceanic crust is subducted slightly, but there is no subduction of continental crust. ● Pile up of continental crust on top of lithosphere due to pressure between plates. ● Fold mountains formed from piles of continental crust. Constructive plate boundaries Oceanic and oceanic: ● Magma rises in between the gap left by the two plates separating, forming new land when it cools. ● Less explosive underwater volcanoes formed as magma rises. ● New land forming on the ocean floor by lava filling the gaps is known as sea floor spreading(as the floor spreads and gets wider). Evidence There is sufficient evidence to prove plate movement, and sea floor spreading (theorised by Harry Hess in the 1940s) provides some of this proof. Paleomagnetism is the study of rocks that show the magnetic fields of the Earth. As new rock is formed and cools the magnetic grains within the rock align with the magnetic poles. Our poles (North and South) switch periodically. Each time these switch the new rocks being formed at plate boundaries align in the opposite direction to the older rock. On the ocean floor either side of constructive plate boundaries, Geologists observed that there are symmetrical bandsof rock with alternating bands of magnetic polarity. This is evidence of sea floor spreading. Continental to continental: ● Any land in the middle of the separation is forced apart, causing a rift valley. ● Volcanoes form where the magma rises. ● Eventually the gap will most likely fill with water and separate completely from the main island. ● The lifted areas of rocks are known as horsts whereas the valley itself is known as a graben. There are further forces influencing how convergent boundaries occur - Ridge push: The slope created when plates move apart has gravity acting upon it as it is at a higher elevation . Gravity pushes the plates further away, widening the gap (as this movement is influenced by gravity, it is known as gravitational sliding). Slap pull: When a plate subducts, the plate sinking into the mantlepulls the rest of the plate(slab) with it, causing further subduction. The focus is the point underground where the earthquake originates from. The epicentre is the area above ground that is directly above the focus. The Ring of Fire accounts for 90% of the world’s Earthquakes (shown in the diagram as the Circum-Pacific belt). The Alpine-Himalayan belt accounts for 5-6% of the world’s earthquakes. Seismicity is measured using a logarithmic richter scale, which is a measure of the strength of seismic waves. The Modified Mercalli Intensity Scaleis also used, which is a rate of the destruction caused (originally the Mercalli scale when developed in 1884, but the name was changed after 1931 when it was modified). Unlike the Richter scale, the Mercalli scale has a definite end at 12 (XII as it is in roman numerals). The Mercalli scale is subjective, meaning sometimes it is disputed as it is dependent on human development being present rather than the strength of the seismic waves. The magnitude of the earthquake is also dependent on the depth of focus. Conservative boundaries have the shallowest boundaries, meaning they are closer to the epicentre and the seismic waves are stronger. Destructive boundaries usually have deeper focuses, meaning the seismic waves are spread over a larger area before they reach the epicentre. This is dependent on the earthquake. Earthquakes are frequent around the world and occur every day at boundaries. Hundreds of smaller magnitude earthquakes that cannot be felt by humans occur every day, whereas the larger earthquakes are less frequent. Earthquakes follow no pattern and are random so there is irregularity between events. Earthquakes are almost impossible to predict. Microquakes may give some indication but the magnitude cannot be predicted as how strong they are is random. Hazards caused by seismic events: ● Shockwaves (seismic waves) - When two plates move side by side, friction builds up and pressure increases; this pressure is stored as potential energy, it cannot move so it just builds up. When the pressure becomes too much, the plates eventually move. All of the energy that has been built up must go somewhere, so it is transferred into kinetic energy, which is released and vibrates throughout the ground. The further away from the focus, the weaker the shockwaves, as the energy is transferred into the surroundings. ● Tsunamis When an oceanic crust is jolted during an earthquake, all of the water above this plate is displaced. The water travels fast but with a low amplitude (height). As it gets closer to the coast, the sea level decreases so there is friction between the sea bed and the waves. This causes the waves to slow down and gain height, creating a wall of water that is on average 10 feet high, but can reach 100 feet. Liquefaction - When soil is saturated, the vibrations of an earthquake cause it to act like a liquid. Soil becomes weaker and more likely to subside when it has large weight on it. ● Landslides and avalanches - Movement in soil or snow will cause it to become unstable. TYPE OF SEISMIC HAZARD EFFECT Environmental Economic Social Political Primary - Earthquake can - Businesses - Buildings - Government cause fault lines destroyed collapse, buildings which destroy the killing/injuring destroyed environment people and - Liquefaction trappingthem. Secondary - Radioactive - Economic - Gas pipes - Political unrest materials and decline as rupture, starting from food other dangerous businesses are fires which can kill shortages or substances destroyed (tax - Water supplies water shortages leaked from breaks etc.) are contaminated - Borrowing power plants - High cost of as pipes burst, money for - Saltwater from rebuilding and spreading international aid tsunamis flood insurance payout disease and - Can be initial freshwater - Sources of causing floods chaos and ecosystems income lost - Tsunamis which ‘lawlessness’ -Soil salinisation lead to damaging e.g. looting flooding Tropical storms form in the Northern Hemisphere from June-November, and the Southern Hemisphere from November-April. The majority of tropical storms do not develop into strong storms and do not reach land. Tropical storms that are higher magnitude and reaching land are thought to be increasing in frequency. Tropical storms are irregular because although they occur in the same areas, their path does not follow a set route - the route taken is dependent on the storm and the climatic conditions. Tropical storms form away from land meaning satellite trackingof cloud formations and movement can be tracked and the general route can be predicted. These projected path of Hurricane Florence estimates to the hour when the hurricane will hit. The first picture tracks 5 days in advance, the second picture is the day after. Note how the tracking changes within 24 hours. The closer the hurricane gets, the easier it is to predict. Storm surges can also be predicted based on the pressure and intensity of the storm. From past storms and climatic trends, the probability of a storm hitting an area can also be predicted. Scientists have predicted how many years it will take for a tropical storm to hit certain areas. Hazards caused by tropical storms: ● High winds - over 300km/hand therefore very strong. Hurricane winds are strong enough to blow a house down, and also blow heavy debris at high speeds, which can obviously cause damage and injure anyone who comes into contact. ● Flooding - coastal/river flooding from storm surgesand heavy rain. River flooding also sends more floodwater to other places, which can cause areas outside of the tropical storm’s path to flood also. ● Landslides - due to soil becoming heavywhen wet with high levels of rain ● Storm surges - Large rise in sea levelscaused by low pressure and high winds, pushing water towards the coast TYPE OF STORM HAZARD EFFECT Environmental Economic Social Political Primary - Beaches eroded - Businesses - Drowning - Government -Sand displaced destroyed - Debriscarried buildings - Coastal habitats - Agricultural land by high winds destroyed such as coral reefs damaged can injure or kill are destroyed - Buildings destroyed Secondary - River flooding/ salt - Rebuildingand - Homelessnes - Issues paying water contamination insurance payout - Polluted back international - Animals displaced - Sources of water supplies aid from flooding e.g. income lost spread disease - Pressure for alligators - Economic decline - Food government to do -Water sources from sources of shortages from more about changing course income destroyed damaged land global warming from blockages Wildfire Hazards Wildfire: A large, uncontrolledfire that quickly spreads through vegetation. Conditions favouring intense wildfires Vegetation Type Thick, close together vegetation allows fires to spread quicklyand easily. Trees and thick bushes lead to more intense wildfires; grasslands do not burn as intensely. Vegetation with flammable oils- like eucalyptus - causes more intense fires also. Fuel Characteristics Vegetation should be dryto allow it to catch. Finer vegetation causes fires to spread quicker, but larger,thicker forms of vegetation burns for longer and more intensely. Climate and Recent Weather Wildfires can occur anywhere in the world, but the most common areas wildfires occur in are located on this map (from 2010). Wildfires occur in a climate that has enough rainfall to have sufficient plant growth, but considerable dry spells and droughts to dry out the fuel. Areas with dry seasonssuch as California allow for intense wildfires. Wind also causes fires to spread quicker. Many climatic events can make wildfires grow more intense and extend wildfire seasons. The Santa Ana Winds and Diablo Winds in California, for example, cause more wildfire damage. El Niño (warm phase) and La Niña (cold phase) are also climatic events that are thought to affect wildfire prevalence. The effects of these phenomena vary throughout the world, but in California El Niño is thought to provide warmer, wetter seasons to grow vegetation, and La Niña’s dryer seasons create more wildfires. Recent temperature increases have caused an increase in the number of wildfiresand an increase the length of wildfire seasons. “Forest fires in the western US have been occurring nearly five times more often since the 1970s and 80s. Such fires are burning more than six times the land area as before, and lasting almost five times longer.” There are also arguments that despite climate change, wildfires are not increasing everywhere. Studies have shown that this is somewhat true; between 1998 and 2015 globally burned area declined about 24 percent. However, this may also be down to agricultural productivity and land use change as there are less areas that can be burned, i.e. less forestry. Fire Behaviour Fires spread quickly on hills as the heat rises. Fire can also ‘jump’ across rivers and into areas due to lit debris which causes it to spread. Wildfire does not just spread in one way; there are three main types of wildfire burning. ● Crown fires burn the entire tree from bottom to top, which is classed as the most dangerous and destructive type of fire. ● Surface fires only burn the leaf litter, meaning they are easy to extinguish. ● Ground fires burn at the dry peat or vegetation beneath the surface, and move slowly through the dried underground. Due to them being underground, they can be difficult to put out and can actually continue to burn throughout the year if the weather conditions allow it. Causes of Wildfires Wildfires can be caused naturally or by humans. The majority of the time, wildfires are caused by human activity. Humans may start fires accidentally or through arson. Natural causes include lightning (being the biggest cause), volcanoes and even spontaneous; Human causes can be lit cigarettes, barbeques, agriculture, train lines and more. Sample Assessment Questions 1. Assess the importance of governance in the successful management of tectonic mega-disasters. (9 marks) _____________________________________________________________________________________________________ _____________________________________________________________________________________________________ _____________________________________________________________________________________________________ _____________________________________________________________________________________________________ _____________________________________________________________________________________________________ _____________________________________________________________________________________________________ _____________________________________________________________________________________________________ _____________________________________________________________________________________________________ _____________________________________________________________________________________________________ _____________________________________________________________________________________________________ _____________________________________________________________________________________________________ _____________________________________________________________________________________________________ _____________________________________________________________________________________________________ _____________________________________________________________________________________________________ _____________________________________________________________________________________________________ _____________________________________________________________________________________________________ _____________________________________________________________________________________________________ _____________________________________________________________________________________________________ _____________________________________________________________________________________________________ _____________________________________________________________________________________________________ _____________________________________________________________________________________________________ _____________________________________________________________________________________________________ _____________________________________________________________________________________________________ _____________________________________________________________________________________________________ _____________________________________________________________________________________________________ _____________________________________________________________________________________________________ _____________________________________________________________________________________________________ _____________________________________________________________________________________________________ _____________________________________________________________________________________________________ 2. Explain why the number of reported earthquakes has increased since 1965 (4 marks) _____________________________________________________________________________________________________ _____________________________________________________________________________________________________ _____________________________________________________________________________________________________ _____________________________________________________________________________________________________ _____________________________________________________________________________________________________ _____________________________________________________________________________________________________ Mark schemes 1. Assess the importance of governance in the successful management of tectonic mega-disasters. (9 marks) Notes for answers The indicative content below is not prescriptive and candidates are not required to include all of it. Other relevant material not suggested below must also be credited. Relevant points may include: AO1 • mega-disasters are large-scale disasters on either an areal scale or in terms of their economic and human impact • they pose serious problems for successful management to minimise impact and mitigate the impact of the disaster • they need often require international management both short term and longer term AO2 • extreme events are likely to pose serious challenges for any governance, however well-planned, e.g. the 2011 Japanese tsunami • extreme events are by their nature unpredictable (1- in a 1000-year events) and so prediction is difficult and prevention is impossible, sometimes secondary and tertiary outcomes occur, e.g. Fukushima • disaster management, pre-, during and after the event, can have a significant impact on losses, e.g. comparison of Japanese tsunami with Indian Ocean, Boxing Day tsunami • strong governance can lead to very effective management of immediate disaster recovery, e.g. Sichuan earthquake in China, as well as the development of longer-term education and community preparation strategies • however, management is expensive and with long return intervals there are strains on budgets that may affect levels of investment, e.g. San Francisco and ‘the big one’ • democratic governance is also often driven by short-term budgetary constraints which make saving money on management measures very tempting, given that it is expensive • governance is important but it has limitations such as the affordability of prediction and prevention measures, especially in the management of mega-disasters immediately after the event, e.g. Haiti, therefore, other factors such as level of development are likely to be more important. 2. Explain why the number of reported earthquakes has increased since 1965 (4 marks) Notes for answers For each reason, award 1 mark for identifying a reason for the increase in the number of reported earthquakes, and a further mark for an appropriate expansion. For example: • increase in the number of recording stations (1) which means more earthquakes are detected which previously might have been missed in remote areas (1) • higher population densities (1), which leads to more reporting because areas are better ‘covered’ (1) • better (more reliable and accurate) detection equipment (1) so smaller magnitude earthquakes are detected which previously might have been missed (1). Accept any other appropriate response. Physical Geography Topics 1. Name one stage of the hazard management cycle. (1) 2. Explain two strategies that are used to modify vulnerability to volcanic hazards. (4) 3. Using a named location, explain how hydrometeorological hazards can contribute to a tectonic disaster. (6) 4. Assess how prediction can contribute to the management of tectonic hazards. (20) 5. Explain two reasons why the number of reported earthquakes has risen since 1960. (4) 6. Explain the causes of tsunamis. (6) 7. Assess the significance of earthquake hazard profiles in relation to the effectiveness of management strategies. (9) 8. Identify one process that occurs only at destructive plate boundaries (1) 9. Explain two secondary hazards caused by earthquakes (4) 10. Explain the tectonic hazards that may result from volcanic activity (6) 11. Assess whether development and governance are the most important factors in understanding the scale of tectonic disasters (20) 12. Define what is meant by disaster (1) 13. Explain two reasons how a government might influence a community’s resilience. (4) 14. Explain why some earthquakes generate secondary hazards. (6) 15. Assess the factors that contribute to increased impacts from some tectonic hazard events. (6) 16. Explain the reasons why volcanoes are more likely along some plate margins than others (4) 17. Assess the contribution of plate-tectonic theory to our knowledge of the Earth’s structure (9) 18. Explain the causes of one earthquake. (6) 19. Assess the relative importance of the hazards associated with destructive plate margins. (20) 20. Explain the hazards cause by one volcanic eruption. (6) 21. Assess the range of hazards caused by explosive volcanic eruptions. (9) 22. Explain the formation of a tsunami. (6) 23. Assess the severity of the various impacts of a tsunami. (9) 24. Assess the reasons why, even within a country, some people are more vulnerable to hazards than others. (9) 25. Assess the relative importance of the concept of vulnerability in understanding hazards impacts. (20) 26. Explain the impacts of one major tectonic disaster. (6) 27. Assess the extent to which a country has been able to meet the pressures placed upon it by a major disaster. (9) 28. Explain why some disasters are economically costly, while others are more costly in terms of human lives. (6) 29. Assess the statement that ‘we are living in a more hazardous world’. (20) 30. Assess the vulnerability of one named country to natural hazards. (9) 31. Assess the extent to which hydro-meteological hazards can produce very similar impacts to hazards with tectonic causes. (20) 32. Explain the value of Park’s hazard-response curve in understanding the management of the impacts of tectonic hazards. (6) 33. Assess the usefulness of theoretical frameworks in understanding the prediction, impact and management of tectonic hazards. (20) 34. Assess the value of hazard-mitigation strategies. (9) 35. With reference to earthquake waves, explain two reasons why it is difficult for buildings to remain intact during an earthquake event. (4) 36. Explain the link between plate boundary type and the strength of earthquake waves (4). 37. Explain the geographical criteria that can be used to decide if a tectonic event is a hazard, disaster or mega-disaster. (6) 38. Explain the correlation between the magnitude and intensity scales used for measuring earthquakes and their secondary hazards. (4) 39. Compare the tectonic hazard impacts in developed countries with those in developing / emerging countries. (6) 40. Explain how emergency planners and engineers may help to modify the impacts of a tectonic hazards. (6) 41. Explain why insurance companies may be interested in encouraging the accurate prediction of, and effective preparation for, a tectonic hazard. (4) 42. Assess the reasons why earthquakes create more disasters than volcanic eruptions (9) 43. Assess the relative importance of the physical characteristics of volcanic eruptions in creating risk for people (20) 44. Explain two process in the formation of offshore bars. (4) 45. Explain how geological structure affects the development of coastal landforms. (6)