In the present study, the Soil and Water Assessment Tool was applied to determine the impacts of changing Land Use and Land Cover (LULC), Geophysical Fluid Dynamics Laboratory – Earth System Model Version 2, and Representative Concentration Pathways (RCP) 8.5 climate scenario on the monthly streamflow in the Subarnarekha basin of India. The results showed increased flow due to a reduction in agricultural area, a rise in built-up area, and a reduction in water bodies due to LULC change. In addition, lower annual precipitation and increased projected temperature were observed under RCP8.5. Although annual precipitation is decreasing, some components of the water balance are slightly increasing. From 2013 to 2020, surface flow increased by 98.85 mm and water yield decreased by 13.33 mm. However, in the climate change scenario, surface flow increased by 142.85 mm. Water yield decreased by 21.88 mm, lateral flow slightly decreased by 7.06 mm, and a further significant decrease 68.37% was noted in groundwater flow. The downward trend in groundwater flow is a serious concern, and therefore, more surface water storage structures must be planned to increase groundwater recharge and capture the increased surface flow. The model performance was statistically tested for NSE (Nash–Sutcliffe efficiency), R², and PBIAS (percent bias). During the calibration period and validation stages, NSE, R², and PBIAS were found to be 0.72, 0.83, and − 15.20%, and 0.85, 0.82, and − 27%, respectively, with the 2013 LULC map. The decreased monthly water availability and declining trend of winter rainfall need to be taken care of while planning the cropping pattern of the basin.

在本研究中，土壤和水评估工具用于确定土地利用和土地覆盖 (LULC) 变化、地球物理流体动力学实验室 - 地球系统模型版本 2 和代表性浓度路径 (RCP) 8.5 气候情景对印度 Subarnarekha 盆地的每月水流量。结果显示，农业面积减少导致流量增加，建成区面积增加，土地利用和覆盖变化导致水体减少。此外，在 RCP8.5 下，年降水量减少，预计气温增加。尽管年降水量正在减少，但水平衡的某些组成部分却略有增加。 2013年至2020年，地表流量增加98.85毫米，产水量减少13.33毫米。然而，在气候变化情景下，地表流量增加了142.85毫米。产水量减少21.88毫米，侧流小幅减少7.06毫米，地下水流量进一步大幅减少68.37%。地下水流量的下降趋势是一个严重的问题，因此必须规划更多的地表水储存结构，以增加地下水补给并捕获增加的地表流量。对模型性能进行了 NSE（纳什-萨特克利夫效率）、R ²和 PBIAS（百分比偏差）的统计测试。在校准期和验证阶段，与 2013 年 LULC 地图相比，NSE、R ²和 PBIAS 分别为 0.72、0.83 和 − 15.20%，以及 0.85、0.82 和 − 27%。在规划流域耕作模式时，需要考虑月可用水量的减少和冬季降雨量的减少趋势。