The report presents a seasonal rainfall-runoff model developed for the Saurashtra region as well as parts of Narmada river basin. The successful planning and implementation of water resources projects require reliable data on volumetric runoff. It is not feasible to have discharge stations in all the river basins of interest given resource constraints. Therefore, regional rainfall-runoff models are preferred. The utility of such models can be improved if rainfall-runoff models for different regions are developed using data specific to the regions.
The report develops a regional model for annual runoff estimation, more particularly a constrained simple bivariate linear regression model, a constrained bivariate non-linear model and a multivariate linear regression model using hydrometeorological data pertaining to twelve sub-basins of Saurashtra region. The efficiency of the models have been evaluated as 61 per cent, 66 per cent and 65 per cent respectively.
Considering the efficiency of the models discussed above, the bivariate non-linear model has a distinct advantage over the multivariate model as it requires only the rainfall data but has an efficiency comparable to that of the multivariate model that requires pan evaporation data in addition to rainfall data.
Because of the complex nature of a natural basin, the direct physical or analytical approach to the determination of runoff is not feasible, and therefore empirical relations like these have to be developed through statistical analysis of measurable factors which are directly related to runoff phenomenon.
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