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Mastering Geology Chapter 17
Groundwater
Worldwide, the largest percentage of freshwater readily available to humans is stored in ______. - ,,,,,,,,answer,,,,,,,,pore spaces between rocks and sediments What geologic roles does groundwater play? - ,,,,,,,,answer,,,,,,,,groundwater erodes bedrock through dissolution groundwater sustains streams during periods of no rainfall When rain falls on land, what factors influence the amount of water that soaks in? - ,,,,,,,,answer,,,,,,,,the nature of the surface material the steepness of the slope the intensity of rainfall the amount of vegetation on the surface How do a gaining stream and a losing stream differ? - ,,,,,,,,answer,,,,,,,,A gaining stream exists when the elevation of the water table is higher than the surface of the stream. in contrast, a losing stream exists when the elevation of the water table is lower than the surface of the stream. A gaining stream gains an influx of groundwater through the streamed, whereas a losing stream loses water to the groundwater through the streamed. Is the water table usually flat like the surface of a kitchen table, and why or why not? - ,,,,,,,,answer,,,,,,,,underground, the water table is shaped like a subdued replica of the land surface. additionally, the water surfaces of rivers and lakes are the level of the water table. What is infiltration? - ,,,,,,,,answer,,,,,,,,water soaking into the ground What is groundwater, and how does it relate to the water table? - ,,,,,,,,answer,,,,,,,,groundwater is water that occupies the zone of saturation within the ground. the water table is the upper limit of the groundwater. Please contrast porosity and permeability. - ,,,,,,,,answer,,,,,,,,porosity is the percentage of the total volume of rock or sediment that consists of pore spaces, whereas permeability.
Low porosity and permeability - ,,,,,,,,answer,,,,,,,,granite gneiss High porosity and permeability - ,,,,,,,,answer,,,,,,,,unconsolidated gravel and sand sandstone conglomerate In order for an aquifer to be useful for reliable water extraction, what kind of porosity and permeability should it have? - ,,,,,,,,answer,,,,,,,,high porosity, high permeability How does the water table change around a pumping water well? - ,,,,,,,,answer,,,,,,,,the water table elevation decreases What is the cone of depression? - ,,,,,,,,answer,,,,,,,,the shape that the water table takes on near a pumping well When will a cone of depression stop enlarging? - ,,,,,,,,answer,,,,,,,,when the amount of water flowing toward the well equals the amount of water being pumped out of the well. When might a well, Well A, go dry? - ,,,,,,,,answer,,,,,,,,when the cone of depression of a second well intersects the deepest part of Well A. What warms the waters that flow at Hot Springs National Park, Arkansas, and at Warm Springs, Georgia? - ,,,,,,,,answer,,,,,,,,the geothermal gradient How does the movement of groundwater relate to hydraulic gradient and hydraulic conductivity? - ,,,,,,,,answer,,,,,,,,groundwater moves more quickly down steeper slopes than down shallow slopes. for this reason, the water table is known as the hydraulic gradient. groundwater flows more rapidly through sediments having greater permeability than through materials having lower permeability. this factor is known as hydraulic conductivity. List the features layered in the cross section of a flowing artesian well from top to bottom. - ,,,,,,,,answer,,,,,,,,pressure surface, flowing artesian well, aquitard, aquifer, aquidtard Why do some artesian wells not flow at Earth's surface? - ,,,,,,,,answer,,,,,,,,the pressure surface is below ground level What is the source of heat for most hot springs and geysers, and how is this reflected in the distribution of these features? - ,,,,,,,,answer,,,,,,,,the heat sources for most hot springs and geysers are magma bodies and igneous rocks. thus, hot springs and geysers are often located where igneous activity occurs.
