Estimation of Total Drainable Water Storage Using GRACE in the Brahmaputra River Basin, India

Abstract

As the Brahmaputra is a transboundary river, the availability of river flow and hydrometeorological data is less in the public domain for the Brahmaputra river basin. Hence, estimation of water balance is difficult for the basin. However, the basin is one of the major populated basins in India and Bangladesh. With the increase in anthropogenic activities, climate change, etc., a proper hydrological and hydraulic study of the basin is essential. Total drainable water storage (TDWS) is one of the fundamental hydrological quantities of a basin that accounts for the long-term average water stored in a basin. In this study, the TDWS of the Brahmaputra basin is estimated. For an ungauged and giant river such as Brahmaputra, where frequent hydrological surveys are not possible, the estimation of TDWS using satellite-based data is highly beneficial and cost-effective. The estimation of TDWS is based on the assumption that storage and discharge have a linear relationship. First, the historical daily discharge data is used to assess the river basin’s base flow parameters (recession constant and base flow index). When passed through Eckhardt’s digital filter, these parameters and the monthly discharge data give the base flow time series for the basin. From the linear relationship between base flow and the gravity recovery and climate experiment’s (GRACE) total water storage anomaly, TDWS for the Brahmaputra basin is estimated. Here in the study, the TDWS is obtained by considering Pandu, Guwahati, as the outlet point for the river catchment.