HYDROLOGICAL ANALYSIS AND BEST MANAGEMENT PRACTICES IN THE HIRAKUD CATCHMENT USING SWAT MODELLING

Abstract

This study examines the management of watershed health in the Hirakud Catchment by integrating trend analysis, hydrologic modelling, and Best Management Practices (BMP) evaluation in an interdisciplinary manner. Specific objectives include climate and discharge data trend analysis, setting up the SWAT model, calibration and validation using a multi-site approach, identifying areas prone to erosion, and implementing and assessing BMPs. Key findings from the trend analysis indicate stable trends in rainfall, maximum temperature, and minimum temperature over time. Streamflow dynamics were analysed for five stations within the catchment, showing different patterns, which indicated that some places experienced substantial decreases in annual as well as monsoonal stream flow volumes statistically significant at certain points. Calibration-validation has been done for Soil and Water Assessment Tool (SWAT), using SWAT calibration and uncertainty program (SWATCUP) sequential uncertainty fitting 2 (SUFI2) which improved prediction accuracy while sensitivity analysis on flow parameters and good NSE, R2 has been obtained for three of the five stations during the calibration and validation periods, with the values of NSE for Ghatora, Kurubhata, and Basantpur as 0.66, 0.68, and 0.66 during the calibration period and 0.54, 0.58, and 0.55 during the validation period, respectively. The soil erosion on basin and subbasin levels is estimated on the basis of the identification of sub-basins with varying degrees of severity, which provides useful information for prioritising interventions against erosion. The erosion in the subbasin is varying from 3.44 t/ha/yr to 63 t/ha/yr. Under various conditions, the use of BMPs shows a considerable decrease in soil loss; the largest reductions are obtained with filter strips and contour bunding, and about 85% to 98% reduction is observed after different BMPs implementations. A significant reduction in sediment transport was seen following the implementation of BMPs in the 17th basin, which is location to the Hirakud reservoir. This finding underscores the effectiveness of BMP interventions in reducing erosion and maintaining soil health. Finally, it is predicted that the most productive 30% of top soil will be swept away in 9.4 years if no action is taken and the erosion rate remains constant (599 t/ha/yr) at the basin level. This study advances our understanding of the dynamics of watersheds and emphasises the value of proactive management techniques for maintaining the health and resilience of watersheds in the face of environmental difficulties.