Identification of Critical Erosion Watersheds for Control Management in Data Scarce Condition Using the SWAT Model

Identification of critical watersheds prone to soil erosion has been performed by using a hydrological model in data scarce Damodar River catchment, located in Jharkhand state of India. Model is calibrated and validated for two watersheds, i.e., (1) Nagwan, $94.43{\mathrm{km}}^2$; and (2) Banikdih, $80.06{\mathrm{km}}^2$, nested within the catchment. The achieved $R^2$ values of predicted monthly runoff and sediment yield varies, respectively, 0.65–0.89 and 0.78–0.84, for both the watersheds during calibration and validation period. Calibration and validation results revealed that model is predicting monthly runoff and sediment yield satisfactory for the two watersheds of the Damodar River catchment. The validated model parameters were then up-scaled to the whole catchment and model was run from 1993–2001 to identify the critical watersheds. Model was successfully used for prioritization of 406 watersheds delineated using the computer software model within the catchment. In delineation process, the boundaries of 175 watersheds matched exactly with the watersheds delineated manually by Damodar Valley Corporation. Out of these 175 watersheds, erosion classes of 157 exactly matched with the manually described erosion class. For remaining 18 watersheds, priority of 10 watersheds was either one class higher or lower, whereas eight watersheds showed complete mismatch. Overall results showed that the hydrological model used in this paper may be helpful in prioritization of management strategies to manage the resources where availability of data is a big concern. Such approach for managing resources is particularly needed in developing countries for better utilization of limited resources.