Simulation of runoff in Baitarani basin using composite and distributed curve number approaches in HEC-HMS model

Abstract

The present study was conducted in Baitarani basin up to Anandapur gauging station of Odisha covering an area of 8603.7 km². Pre-processing of basin from digital elevation model (DEM) was done using HEC-Geo-HMS extension and spatial analyst tool in ArcGIS. These pre-processed files were then imported to HEC-HMS for simulating runoff. In this study, runoff simulation was done using two methods, viz., composite and distributed curve number (CN) approaches. SCS curve number method was used for computation of runoff volume, SCS UH method for direct runoff, constant- monthly varying base flow method for base flow and Muskingum method for flow routing.  The model was calibrated and validated using both composite and distributed CN approaches. Data from 1^st January, 2007 to 31^st December, 2013 were used for calibration and 1^st January, 2014 to 31^st December, 2016 were used for validation. During the calibration period of composite CN approach, the statistical parameters like Nash-Sutcliffe efficiency (NSE), Coefficient of determination (R²), Percent bias (PBIAS) and RMSE-observations standard deviation ratio (RSR) were found to be 0.51, 0.63, 12.82 and 0.7, respectively and during the validation period they were found to be 0.53, 0.54,    -19.73 and 0.7, respectively. In case of distributed CN approach, the statistical parameters like NSE, R², PBIAS and RSR were found to be 0.62, 0.63, -8.64 and 0.6, respectively during the calibration period and 0.67, 0.66, -2.25 and 0.6,  respectively during the validation period. The study indicated that distributed CN approach is more accurate than composite CN approach in simulation of runoff using HEC-HMS model.