Journal of Hydrologic Engineering

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.

In the face of rising greenhouse gas concentrations, our study investigates the intricate regional dynamics of hydrological responses across three vital river basins of the Western Ghats of India. Employing advanced eXtreme Gradient Boosting (XGBoost) ensemble models based on Coupled Model Intercomparison Project (CMIP6) data, the article explores the anticipated changes in the climate variables under two future scenarios. The findings reveal a compelling narrative of temperature fluctuations, with increased warming in future decades from November to June ushering in warmer winters and extended summer seasons. These climatic shifts carry profound implications for rainfall patterns, potentially disrupting rainfall during the pivotal months of June and July up to the decade 2030s, with a more pronounced increase in the Purna River Basin (PRB) after the decade 2050s. The projected future climate scenarios indicate that the Vamanapuram River Basin (VRB) and PRB will experience contrasting patterns of dry and wet events, with the VRB facing severe to extreme dry and the PRB witnessing increased moderate to extreme wet events under high-emission scenarios. Additionally, the PRB may experience the paradox of increasing wetness and aridity. These insights provide crucial guidance for policy formulation and adaptation measures to safeguard agriculture and other vital sectors in the face of evolving climate conditions.