QUANTITATIVE PRECIPITATION FORECASTING OVER NARMADA CATCHMENT

Quantitative precipitation forecasting (QPF) has been attempted over t he Narmada Catchment following a statistical approach. The catchment h as been divided into five sub-regions for the development of QPF model s with a maximum lead-time of 24 hours. For this purpose the data of d aily rainfall from 56 raingauge stations, twice daily observations on different surface meteorological parameters from 28 meteorological obs ervatories and upper air data from 11 aerological stations for the nin e monsoon seasons of 1972-1980 have been utilized. The horizontal dive rgence, relative vorticity, vertical velocity and moisture divergence are computed using the kinematic method at different pressure levels a nd used as independent variables along with the rainfall and surface m eteorological parameters. Multiple linear regression equations have be en developed using the stepwise procedure separately with actual and s quare root and log-transformed rainfall using 8-year data (1972-1979). When these equations were verified with an independent data for the m onsoon season of 1980, it was found that the transformed rainfall equa tions fared much better compared to the actual rainfall equations. The performance of the forecasts of QPF model compared to the climatologi cal and persistence forecasts has been assessed by computing the verif ication scores using the forecasts for the monsoon season of 1980.