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# Irrigation (21-40)

Updated: Apr 8, 2020

21.If the intensity of rainfall is more than the infiltration capacity of soil, then the

infiltration rate will be equal to infiltration capacity

22.Cyclonic precipitation is caused by lifting of an air mass due to pressure difference

23.Which of the following is a non-recording raingauge ?

Simon's raingauge

24.A raingauge should preferably be fixed in an open space

25.If allowable percentage error in the estimate of basic rainfall is E and coefficient of variation of rainfall is Cv,then the optimum number of raingauges is

given by 26.Which of the following types of rain gauges is used for measuring rain in remote hilly inaccessible areas ? tipping bucket type

27.Rate of evaporation from a water surface increases if

difference of vapour pressure between water and air is increased,concentration of soluble solids in water is decreased

28.A 70% index of wetness means rain deficiency of 30%

29.Under the same conditions, which of the following shapes of water surface will

give the highest rate of evaporation ? convex water surface

30.To estimate the rainfall over a catchment, the number of rain gauges required per unit area is large for hilly areas.Rainfall gradient is steep.

31.When surface of transpiration is submerged under water, then potential

evapotranspiration is much more than evapotranspiration

32.Coefficient of variation is given by (standard deviation/mean) X 100

33.Unit of runoff in M.K.S. system is cubic metre/sec

34.The runoff increases with increase in intensity of rain

35.The area between the isohyets 45 cm and 55 cm is 100 square km and between 55 cm and 65 cm is 150 square km. The average depth of annual precipitation over

the above basin of 250 square km will be 56 cm

36.A current meter is used to measure the velocity of flow of water

37.If it rains between 2 P.M. and 3 P.M. and the entire basin area just starts contributing water at 3 P.M. to the outlet, then time of concentration will be

60 minutes

38. The rainfall on five successive days were measured as 100 mm, 80 mm, 60 mm, 40 mm and 20 mm' respectively. If the infiltration index or the storm loss rate for the catchment area is earlier estimated as 50 mm/day, the total surface run off will be 90 mm

39.The normal annual precipitation at stations X, A, B and C are 700 mm, 1000

mm, 900 mm and 800 mm respectively. If the storm precipitation at three station A, B and C were 100 mm, 90 mm and 80 mm respectively, then the storm precipitation for station X will be 70 mm

40.The best unit duration of storm for a unit hydrograph is one-fourth of basin lag