Abstract
A computerβbased water budget technique was developed considering the land gradient [{vertical interval between two adjacent field bunds (levees)=20βcm} Γ· the distance between the bunds] and paddy field bunds (viz. 16, 18, 20, 22, 24βcm) in its formulation for computing daily runoff from coastal paddy areas in India. The inputs used in the water budget technique consist of limited meteorological data that are easily available in India. The water budget technique was validated with the modified curve number method and the measured data collected during 2001 in a coastal paddy area of Orissa (east coast of India close to Bay of Bengal), India and its superiority was found. In most of the cases (barring a few events of 16βcm and 18βcm paddy field bunds for the water budget technique), statistically both methods differed significantly from each other while generating daily runoff. The estimate of the surface drainage coefficient (the amount of excess surface runoff water to be drained from the crop field during a 24βhour period) for a 5βyear return period was computed as 100βmm day^β1^ (taking the 22βcm paddy field bund) and 109βmm day^β1^ in case of the water budget technique and modified curve number method, respectively. Copyright Β© 2004 John Wiley & Sons, Ltd.