Identification of critical sub-watersheds in Hamp watershed of upper Mahanadi basin using Arc-SWAT

Abstract

Hydrologic and water quality investigations are fundamental to any watershed management programme. Surface hydrologic modelling of watershed mainly includes processes like runoff and transport of sediment as well as pollutants from the watershed. Mahanadi is one of the major inter-state east flowing perennial rivers in peninsular India. Hamp watershed of Seonath sub-basin of upper Mahanadi basin was selected for this study to estimate sediment yield, and identification of critical agricultural sub-watershed using soil and water assessment tool (SWAT) interfaced with geographic information system (GIS) i.e. Arc-SWAT. The study area was divided into 14 sub-watersheds considering topographical parameters derived from digital elevation model (DEM) and drainage network. Land cover, soil layers, and DEM were used to generate 207 hydrological response units (HRUs) for analysis of daily and monthly sediment yield for 2004-2008 (calibration period) and 2010-2013 (validation period). Adequately calibrated and validated Arc-SWAT model was used to estimate soil loss for identification of critical sub-watersheds of the Hamp watershed from upper Mahanadi river basin. The sediment yield and runoff estimation matched consistently well with daily and monthly measured values throughout the season. The coefficient of determination (R2) of 0.693 and 0.96 and Nash-Sutcliffe efficiency (E ) NS was found to be 0.62 and 0.94 for daily and monthly sediment yield, respectively, indicating a close relationship between measured and predicted sediment yield. On the basis of average annual sediment yield of this study, sub-watersheds WS4, WS8, WS11, and WS10 were considered as critical watersheds, and the most critical sub- watershed WS4 with runoff and sediment yield of 245.97 mm and 18.18 t ha-1, respectively was categorized under high priority for adoption of conservation measures to reduce soil and runoff loss.