Question

The design annual rainfall for the catchment of a proposed reservoir has been computed to be 99 cm. The catchment area contributing to the proposed reservoir is 1000 sq.km having a mean annual temperature of 20°C. Calculate the annual design catchment yield for the reservoir using Khosla’s formula.

(a) 89.4 M.m^3

(b) 8.94 M.m^3

(c) 894 m^3

(d) 894 M.m^3

I got this question by my college professor while I was bunking the class.

The origin of the question is Reservoir Capacity Determination Using Hydrograph and Mass-curve in chapter Reservoirs and Dam Reservoirs Planning of Irrigation Engineering

Answer 1

Right choice is (d) 894 M.m^3

The explanation is: Using Khosla’s formula –

Q = P – 0.48 Tm where, Rainfall (P) = 99 cm and Mean annual temperature (Tm) = 20°C

Q = 99 – 0.48 x 20 = 89.4 cm = 0.894 m

The total yield produced from the given catchment = 0.894 x 1000 x 10^6 = 894 M.m^3.