The report is the first of a two-part study on water availability for the Ken river system and attempts to evaluate the direct surface runoff in the smaller basins, where gauging sites are not available. In this study on water availability in Ken river basin, rainfall-runoff modeling in the Sonar, Bearma and Bebas river basins, which are the sub-basins of the Ken river system, have been carried out using the Soil Conservation Services Curve Number (SCS-CN) model.
This is a widely used hydrological model for calculating the runoff using rainfall and Curve Number (CN). The SCS-CN is a quantitative descriptor of the land use, land cover and soil complex characteristics of a watershed. The CN is an index that represents the watershed runoff potential.
The well established techniques like unit hydrograph technique, conceptual models and physically based models require a certain amount of historical data for establishing various parameters. However, due to sparse gauging network available in most of the Indian catchments, particularly for small catchments, it becomes very difficult for such techniques to be directly applicable.
The latest technique of satellite remote sensing provides real time and reasonably accurate information of the prevailing land use pattern. In this study, various land-use classes have been interpreted using the IRS IA, LISS II satellite imageries.
The large sub-basins of river Ken namely Sonar and Bearma have been further sub-divided into smaller sub-basins and the runoff for each of these sub-basins has been computed after establishing their respective SCS-CN numbers. The runoff from these smaller sub-basins was summed up, taking the effect of time lag and discharges were predicted for two gauging stations and compared with the recorded surface runoff.
The predicted runoff values at these gauging sites are quite in agreement with the available observed surface runoff.
The second part of the study is a continuation of this work and deals with the base flow components using suitable models and flow duration curve techniques employed for assessing the dependable flows in these ungauged sub-basins.
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