Question

The valley storage reduces the effective storage capacity of a reservoir.

(a) True

(b) False

This question was addressed to me in an interview.

The question is from Capacity and Area Elevation Curves of a Reservoir Site in portion Reservoirs and Dam Reservoirs Planning of Irrigation Engineering

Answer 1

Right answer is (a) True

Easiest explanation: The effective storage for flood mitigation is equal to the useful storage plus surcharge storage minus valley storage i.e. storage corresponding to the rate of inflow in the reservoir. The actual net increase in the storage is equal to the storage capacity of the reservoir minus the natural valley storage. Thus, the available storage is reduced for flood mitigation reservoir.