Evaluation of daily rainfall-runoff simulations in Narmada river basin

Narmada in the central India is the largest west flowing river in the Indian Peninsula. Several rainfallrunoff models have been applied for different sub-basins of Narmada in the past. However, no detailed study exists on the calibration and validation of a rainfall-runoff model for the entire Narmada basin using daily observed rainfall and runoff data. In the present study, the Soil and Water Assessment Tool (SWAT) model in ArcGIS configuration has been used to simulate runoff characteristics in the entire Narmada basin. Daily observed rainfall and temperature values has been used for 8 years and the model has been calibrated and validated for four gauge and discharge stations at various locations of the basin. In this study, model runs with three different combinations (with different time period for calibration and validation) have been carried out. It is found that model performance is reasonably good for upstream gauge stations. However, for downstream gauge stations, the simulated runoff does not agree well with that of observations. It is found that validation skill depends on the rainfall characteristics of the calibration years. For first two combinations of calibration and validation, the model skill is better than the last combination. Experiments have also been carried out to examine the role of number of hydrological response units (HRUs) used in the simulations. This study highlights the fact that large number of years should be used to calibrate the SWAT model for obtaining better skill in estimating rainfall-runoff in the entire Narmada basin. © 2015 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.