WITHDRAWN: Snowmelt runoff estimation in Bhagirathi basin using WinSRM approach

Abstract

Abstract The present study estimates snowmelt runoff in the sub-basins of the river Ganga using the WinSRM-snowmelt runoff Model (SRM). A temperature index model is used to calculate the discharge from simulated snowmelt runoff for the ablation months (from April to August) during 2010-14. The variables of the model include precipitation, rainfall, air temperature and Snow Cover Area (SCA). Air temperature and precipitation are obtained from the Soil-Water Assessment Tool (SWAT) over the delineated zones (base stations) of the basin. The SCA is estimated using the MODIS snow product: MOD10A2 data with 8-day period or composite snow cover area (SCA) of 500m spatial resolution. Results show that the discharge starts from April and maintains a high flow with mean value of 134 + 18.16 m 3 s e c − 1 until August. However, the model underestimates the average runoff volume by 8% in 2010 and overestimates by 10% in 2014. The observed snow volume difference (Dv) is +8.26 and -8.96 for the years 2010 and 2014 respectively. The measured and simulated discharge rates are found to be in agreement with correlation coefficients in the range of 0.83 to 0.96 during the 2010-2014 period. Simulated discharge rates showed strong variability with typically highest values in mid July-August (e.g. 520 m 3 s e c − 1 in 2010). The model also showed some additional peaks in the month of May as seen in measurements during 2011, 2013, and 2014. Average runoff rates during the monsoon season (June-August) were estimated to be in the range of 108 − 175 m 3 s e c − 1 during the study period. This study reveals the contiguity of the model results as compared with the real time observations and indicates potential for improvement with the usage of satellite derived inputs within the deviation limits. The findings from the study have implications for better monitoring of glacier health and natural resource management in the Himalaya, where meteorological and hydrological observations are limited.