In this study, the modified version of the Soil Conservation Services-Curve Number (SCS-CN) by Mishra and Singh (1998a) was employed to the data of 14 watersheds falling in the arid (Rajasthan) and 2 watersheds in the sub-humid (Madhya Pradesh and Uttar Pradesh) regions of India and the results were compared with those of the existing SCS-CN method. The modified version is found to perform better than the existing SCS-CN method in all applications to the data of 16 watersheds.
Rainfall-runoff modeling provides a useful input to water resources planning and management. The SCS-CN method is one of the most popular methods for computing the volume of surface runoff for a given rainfall event from small agricultural watersheds.
Mishra and Singh found the basis of the SCS hypothesis in the empirical rainfall-runoff relation expressed by Mockus (1949). The data of the watersheds are utilized for estimating the parameters and evaluating the performance of the modified and existing SCS-CN methods using a goodness of fit criteria with Root Mean Square (RMS) as a measure of the model performance.
The former model yielded RMS values in the range (8.417, 59.523) and the latter in the range (19.455, 67.405) for the watersheds of the arid region; and sequentially the RMS values for the former and the latter models were (98.687, 121.879) and (94.380, 100.185) for the Manot and Ramganga watersheds falling in the sub-humid regions respectively.
The lower RMS value arrived at through the modified version of the SCS-CN method in all the applications, underscores its better performance as compared to the existing method.
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