Assessing Efficacy of Baseflow Separation Techniques in a Himalayan River Basin, Northern India

The goal of this study is to evaluate the performance of salient baseflow estimation techniques in a river basin of Northern India. Daily precipitation data (2000 to 2021) and daily streamflow data (2006 to 2014) were used in this study. Four digital filtering methods for baseflow estimation were selected viz., Eckhardt, Chapman-Maxwell (CM), Bflow Program, and Exponential Weighted Moving Average (EWMA). Comparative evaluation of the selected methods was performed using the Baseflow Index (BFI) and visual inspection. Also, the results of these methods were verified following a novel approach and their efficacy was assessed using statistical and graphical indicators. The mean monthly streamflow was maximum (40.52%) in June and minimum (10.87%) in April. The comparative evaluation of the methods revealed that the Bflow Program performed the best (BFI = 0.75 − 0.65) in all years, while the EWMA method performed the worst (BFI = 1.05 − 0.78). The verification of the baseflow estimation methods indicated that the Bflow Program performed better in most years (RMSE = 13.34 − 8.14 m³/s, and PBIAS = 12.28 − 22.7%) than other methods. Therefore, the Bflow Program is recommended for the study area. The proposed novel approach for verification is efficient, cost-effective and easy-to-use, and it is applicable to diverse river basins. The findings of this study are very useful to the decision-makers of the region for developing appropriate strategies for the sustainable management of dwindling water resources and ecosystems under changing climate and socio-economic conditions.

Baseflow separation methods are rigorously evaluated in a basin of the Himalayas.