TR(BR)-12/97-98 : Study of impact of wet and dry spells in rainfall records on the water availability estimates

Abstract

This report examines the effect of periodicity in the rainfall records on the water availability of a basin. Based on the rainfall-runoff record of a shorter period, runoff series for a longer period is developed using a water balance model. Percent deviation in water availability estimations computed using a short term wet or dry record to that of complete record is examined. Effect of length of time series on the water availability estimates is also studied.

Results indicate that a minimum of seven and half years of record is needed for estimation of water availability on a monthly scale for Daman ganga basin and the effect of wet and dry spells play a crucial role in the determination of water availability.