Q.
1.Calculate the precipitable water (mm) in a 10-km high saturated atmospheric column if the surface conditions are : air temperature = 20oC, pressure = 101.3 kPa and the lapse rate (α) is 5.0oC/km
2.(a) A reservoir with a surface area of 500 hectares had the following average values of parameters during a given week: water temperature = 20oC, relative humidity = 40% and wind velocity at 1.0 m above the ground = 28 km/h. Estimate the average daily evaporation from the lake and the total volume of water evaporated from the lake during that one week.
(b) Calculate by energy balance method, the evaporation rate from an open water surface, if the net radiation is 220 W/m2 and the temperature is 26oC, assuming no sensible heat or ground heat flux.
3.(b) A catchment is at a latitude of 12o18’N, and at an elevation of 750 m above MSL.
The mean monthly temperatures observed are given below :
Month Jan Feb March April May June July Aug Sept Oct Nov Dec
Mean monthly Temp. (oC) 1.8 20.5 26.0 28.0 25.0 25.0 23.0 23.5 24.5 24.5 23.0 19.0
Calculate the monthly and annual PET for this catchments using Thornthwaite formula.
4.(a) For a catchment in Uttar Pradesh, the mean monthly rainfall and temperature are given below. Calculate the annual runoff coefficient by Khosla formula.
Month Jan Feb March April May June July Aug Sept Oct Nov Dec
Temp. (˚C) 12 17 20 28 30 35 30 30 27 28 20 14
Rainfall
(mm) 6 4 3 0 0 10 37 30 10 2 2 5
5.Observed values of runoff, at a stream gauging site are given below. Upstream of the gauging site, a weir, built across the stream, diverts 2.8 and 0.6 Mm3 of water per month for use in irrigation and industry. The return flows from irrigation, estimated at 1 Mm3 per month, and from the industry at 0.8 Mm3 per month, joins the stream upstream of the gauging site. Estimate the virgin flow of the river. If the catchment area is 115 km2 and the average annual rainfall is 180 cm also determine the runoff-rainfall ratio.
Month Jan Feb March April May June July Aug Sept Oct Nov Dec
Runoff (mm) 2.2 1.6 0.8 0.6 2.1 8.0 28.0 22.0 11.0 9.0 7.0 2.0
6.The velocity of float in a stream was observed to be 6.0 m/s. Compute the average flow velocity corresponding to this observation. Adopt a reasonable value of the required coefficient and explain why this coefficient is needed.
7.In a rectangular channel which is 15 m wide, the depth of flow and cross-sectional areas are measured as 3.5 m, 52.5 m2 and 3.4 m, 51.0 m2 at two sections 250 m apart. The drop in the water surface elevation was found to be 0.10 m. Assuming Manning’s coefficient to be 0.016 estimate the discharge through the channel.
