Evaluation of Conservation Treatment Measures for Runoff Reduction using A SWAT Model-Based Approach: A Case study in Hindol Sub-watershed, Dhenkanal, Odisha

The Hindol block in Dhenkanal, Odisha, with an average annual rainfall exceeding 1200 mm, faces persistent challenges in managing runoff and sedimentation. This study evaluates the effectiveness of soil and water conservation (SWC) techniques in mitigating runoff across clusters of untreated micro-watersheds within this region.

A water balance analysis, focusing primarily on surface runoff, was conducted using the Soil and Water Assessment Tool (SWAT). The model incorporated high-resolution datasets, including digital elevation models, land use, recent Land Resource Inventory (LRI) data, and local weather records. Based on the hydrological assessment, a series of SWC interventions were designed, including contour bunding, trench cum bunds, staggered trenches, and Drainage Line Treatment (DLT) measures such as loose boulder check dams, brushwood check dams, and gabions.

These interventions were simulated in the SWAT model by adjusting critical hydrological parameters, such as Curve Number (CN2), Universal Soil Loss Equation Factor (USLE_K), Manning’s roughness coefficient (CH_N), and tributary slope (CH_S). Comparative analyses of pre and post implementation scenarios demonstrated significant reductions in runoff volumes. The extent of these reductions varied with the type and combination of conservation measures implemented.

The results underscore the potential of integrated conservation strategies to mitigate runoff and restore hydrological balance in sub-watersheds with similar agro-climatic and topographical conditions. This study provides practical insights for watershed management practitioners and policymakers, facilitating informed decisions on selecting and implementing conservation measures to address runoff and sedimentation challenges.