DEPTH-AREA-DURATION ANALYSIS OF SHORT DURATION RAINFALLS

Abstract

The runoff from catchments is one of the important informations needed for the planning of the water resources projects. The design engineers generally do not have simple and reliable methods for estimation of this information particularly when runoff due to small duration rainfalls, (i.e. less than 24 hr) are of interest. Rainfall Depth-Area-Duration relationship is often used for the purpose of runoff estimation and other design purpose.Various types of empirical equations and models have been proposed for estimation of average rainfall depth, for rainfall durations more than or equal to 24 hours. However, no study is available regarding Depth-Area-Duration relationship for smaller duration storms (i.e. less than 24 hours). Keeping this in view, in the present investigation, the available data from 36 rainfall stations related to four large river catchments in India i.e. Ramganga, Gomati, Yamuna and Ghaghara have been used to develop a simple Depth-Area-Duration relationship. Attempt is made to study the variation of rainfall depth with catchment area, duration of rainfall and geographical location of the raingauge station.