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HYDROLOGY MULTIPLE CHOICE.
The percentage of earth covered by oceans is about (a) 31% (b) 51% (c) 71% (d) 97% - ANSWERc The percentage of total quantity of water in the world that is saline is about (a) 71% (b) 33% (c) 67% (d) 97% - ANSWERd The percentage of total quantity of fresh water in the world available in the liquid form is about (a) 30% (b) 70% (c) 11% (d) 51% - ANSWERa If the average annual rainfall and evaporation over land masses and oceans of the earth are considered it would be found that (a) over the land mass the annual evaporation is the same as the annual precipitation
(b) about 9% more water evaporates from the oceans than what falls back on them as precipitation (c) over the ocean about 19% more rain falls than what is evaporated (d) over the oceans about 19% more water evaporates than what falls back on them as precipitation. - ANSWERb Considering the ratio of annual precipitation to runoff = r for all the continents on the earth. (a) Asia has the largest value of the ratio r. (b) Europe has the smallest value of ro. (c) Africa has the smallest value of ro. (d) Australia has the smallest value of r. - ANSWERc In the hydrological cycle the average residence time of water in the global (a) atmospheric moisture is larger than that in the global rivers (b) oceans is smaller than that of the global groundwater (c) rivers is larger than that of the global groundwater (d) oceans is larger than that of the global groundwater. - ANSWERd A watershed has an area of 300 ha. Due to a 10 cm rainfall event over the watershed a stream flow is generated and at the outlet of the watershed it lasts for 10 hours. Assuming a runoff/rainfall ratio of 0.20 for this event, the average stream flow rate at the outlet in this period of 10 hours is (a) 1.33 m⅝ (b) 16.7 m¾
A tropical cyclone in the northern hemisphere is a zone of (a) low pressure with clock wise wind (b) low pressure with anticlockwise wind c) nign pressure with clocKwise wind (d) high pressure with anticlockwise wind - ANSWERb Orographic precipitation occurs due to air masses being lifted to higher altitudes by (a) the density difference of air masses (b) a frontal action (c) the presence of mountain barriers (d) extratropical cyclones. - ANSWERc The average annual rainfall over the whole of India is estimated as (a) 189 cm (b) 319 cm (c) 89 cm (d) 117 cm - ANSWERd Variability of annual rainfall in India is (a) least in regions of scanty rainfall (b) largest in regions of high rainfall (c) least in regions of high rainfall (d) largest in coastal areas. - ANSWERc
The standard Symons' type raingauge has a collecting area of diameter (a) 12.7 cm (b) 10 cm (c) 5.08 cm (d) 25.4 cm. - ANSWERa The standard recording raingauge adopted in India is of (a) weighing bucket type (b) natural siphon type (C) tipping bucket type (a) telemetry type - ANSWERb The following recording raingauges does not produce the mass curve of precipitation as (a) Symons' raingauge (b) tipping bucket type gauge (c) weighing bucket tvpe gauge (d) natural siphon gauge - ANSWERb When specific information about the density of snowfall is not available, the water equiva. lent of snowtall is taken as (a) 50% (b) 30% (c) 10% (d) 90% - ANSWERc
(d) to estimate the missing rainfall data - ANSWERa The mass curve of rainfall of a storm is a plot of (a) rainfall depths for various equal durations plotted in decreasing order (b) rainfall intensity vs time in chronological order (c) accumulated rainfall intensity vs time (d) accumulated precipitation vs time in chronological order. - ANSWERd A plot between rainfall intensity vs time is called as (a) hydrograph (b) mass curve (c) hyetograph (d) isohyet - ANSWERc A hyetograph is a plot of (a) Cumulative rainfall vs time (c) rainfall depth vs duration (b) rainfall intensity vs time (d) discharge vs time - ANSWERb The Thiessen polygon is (a) a polygon obtained by joining adjoining raingauge stations (b) a representative area used for weighing the observed station precipitation (c) an area used in the construction of depth-area curves
(d) the descriptive term for the shape of a hydrograph. - ANSWERb An isohyet is a line joining point having (a) equal evaporation value (b) equal barometric pressure (c) equal height above the MSL (d equal rainfall depth in a given duration - ANSWERd By DAD analysis the maximum average depth over an area of 10* km due to one day storm is found to be 47 cm. For the same area the maximum average depth for a three dav storm can be expected to be (a) <47 cm (b) > 47 cm (c) 47 cm (d) inadequate information to conclude. - ANSWERb Depth-Area-Duration curves of precipitation are drawn as (a) minimizing envelopes through the appropriate data points (b) maximizing envelopes through the appropriate data point (c) best fit mean curves through the appropriate data points (d) best fit straight lines through the appropriate data points - ANSWERb Depth-Area-Duration curves of precipitation at a station would normally be (a)curves. concave upwards. with duration increasing outward (b) curves. concave downwards, with duration increasing outward
(c) 0. (d) 0.500 - ANSWERb A one day rainfall of 18 hours at Station C was found to have a return period of 50 years. The probability that a one-day raintall of this or larger magnitude will not occur at station C during next 50 years is (a) 0. (b) 0. (c) 0. (d) 0.371 - ANSWERc If the maximum depth of a 50 years- 15 - rainfall depth at Bhubaneshwar is 260 mm, the 50 year-3 h-maximum rainfall depth at the same place is (a) < 260 mm (b) > 260 mm (c) = 260 mm (d) inadequate data to conclude anything. - ANSWERa The probable maximum depth of precipitation over a catchment is given by the relation PMP (a) P + KA" (6) P+K (c) P exp (-K A") (d) mP - ANSWERb
If ew and ea are the saturated vapour pressures of the water surtace and air respectively, the Dalton's law for evaporation B, in unit time is given by E, = (a) (ew - ea) (b) Kew ea (c) K(ew - ea) (d) K(ew + ea) - ANSWERc The average pan coefficient for the standard US Weather Bureau class A pan is (a) 0. (5) 0. (c) 0. (6) 0.20 - ANSWERb A canal Is 80 km long and has an average surtace width of 13 m. It the evaporation measured in a class A pan is 0.5 cm/day, the volume of water evaporated in a month of 30 days is (in m') (a) 12600 (b) 18000 (c) 180000 (d) 126000 - ANSWERd The ISI standard pan evaporimeter is the (a) same as the Op class A pan (b) has an average pan coefficient value of 0.
(b) nignt-time only (c) land surface only (d) none of these. - ANSWERd Lysimeter is used to measure (a) infiltration (b evaporation (c) evapotranpiration (a) vapour pressure. - ANSWERc The highest value of annual evapotranspiration in India is at Raikot. Guiarat. Here the 90n119 PH 18 960111 (a) 150 cm (b) 150 mm (c) 210 cm (d) 310 cm. - ANSWERc Interception losses (a) include evaporation, through flow and stemflow (b) consists of onlv evaporation loss (c) includes evaporation and transpiration losses (d) consists of only stemflow. - ANSWERb
The infiltration capacity of a soil was measured under fairly identical general conditions by a flooding type infiltrometer as fand by a rainfall simulator as f.. One can expect (a) f=f, (b) f>f, (c) f For a basin, in a given period Ar, there is no change in the groundwater and soil water status. It P = precipitation. R = total runoft. b = Evapotransbiration and As = increase in the surface water storage in the basin, the hydrological water budget equation states (a) P = R - E ± Δs (b) P = R - E - Δs (c) P = R - E + Δs (d) None of these - ANSWERc The science and practice of water flow measurement is known as (a) Hypsometry (b) Hydro-meteorology (c) Fluvimetry (d) Hydrometry - ANSWERd The following is not a direct stream flow determination technique (a) Dilution method (b) Ultrasonic method (c) Area-velocity method (d) Slope-area method - ANSWERd A stilling well is required when the stage measurement is made by employing a (a) bubble gauge
(b) float gauge recorder (c) vertical staff gauge (d) inclined staff gauge - ANSWERb In a river carrying a discharge of 142 m⅘, the stage at a station A was 3.6 m and the water surface slope was 1 in 6000. If during a flood the stage at A was 3.6 m and the water surface slope was 1/3000, the flood discharge (in m'⅗) was approximately (a) 100 (b) 284 (c) 71 (d) 200 - ANSWERd In a triangular channel the top width and depth of flow were 2.0 m and 0.9 m respec-tively. Velocity measurements on the centre line at 18 cm and 72 cm below water surface indicated velocities of 0.60 m/s and 0.40 m/s respectively. The discharge in the channel (in m⅔) is (a) 0. (b) 1. (c) 0. (d) none of these. - ANSWERc In the moving-boat method of stream-flow measurement, the essential measurements are (a) the velocity recorded by the current meter, the depths and the speed of the boat.
The stage discharge relation in a river during the passage of a flood wave is measured. If Or = discharge at a stage when the water surface was rising and Q = discharge at the same stage when the water surface was falling, then (a) QF= OR (b) OR > OF (c) OR < QF (d) QR/QF = constant at all stages - ANSWERb A large irrigation canal can be approximated as a wide rectangular channel and Man-ning's formula is applicable to describe the flow in it. If the gauge (G) is related to discharge (Q) as 9 = C(G - a) where a = gauge height at zero discharge, the value of B is (a) 1. (b) 1. (c) 2. (d) 0.67 - ANSWERa The dilution method of stream gauging is ideally suited for measuring discharges in (a) a large alluvial river (b) flood flow in a mountain stream (c) steady flow in a small turbulent stream
(d) a stretch of a river having heavy industrial pollution loads. - ANSWERc A 400 g/| solution of common salt was discharged into a stream at a constant rate of 45 Is. At a downstream section where the salt solution is known to have completely mixed with the stream flow the equilibrium concentration was read as 120 ppm. If a background concentration of 20 ppm is applicable, the discharge in the stream can be estimated to be, in m%, as (a) 150 (b) 180 (c) 117 (d) 889 - ANSWERb In the gulp method of stream gauging by dilution technique, 60 litres of chemical X with concentration of 250 g/litre is introduced suddenly in to the stream at a section. At a downstream monitoring section the concentration profile of chemical X that crossed the section was found to be a triangle with a base of 10 hours and a peak of 0.10 pm. The discharge in the stream can be estimated to be about (a) 83 m⅝ (b) 180 m% (c) 15000 m°/ (d) 833 m° - ANSWERa The slope-area method is extensively used in (a) development of rating curve (b) estimation of flood discharge based on high-water marks
