Quantifying Groundwater Depletion in an Intensively Cultivated Alluvial Region Using Integrated Remote Sensing, GIS, and Water Balance Approach: A Case Study of Patna District, India

Abstract

Groundwater depletion has become a serious problem for areas with intensive farming because it Endangers both their water resources and their ability to maintain agricultural practices. The research measures groundwater depletion in Patna District, Bihar (India) through a unified framework that combines groundwater level assessment with remote sensing data and GIS spatial methods. The study uses a basic volumetric method with satellite data because it needs to assess Power plants which have limited access to data. The analysis shows that groundwater levels in 2010 to 2024 period experienced a steady drop which resulted in a 4.9-meter water table reduction that reached 11.1 meters. The total groundwater storage loss is calculated at 2.35 × 10⁹ m³ using a specific yield of 0.15 and the annual depletion rate amounts to 1.68 × 10⁸ m³ per year. The remote sensing study shows that NDVI has grown to 0.59 from its previous value of 0.42 because agricultural activity has increased but NDWI has decreased to 0.10 from its former value of 0.21 which shows that surface water resources have reduced. The correlation analysis demonstrates that groundwater decline has a strong connection with NDVI (r = +0.71) and NDWI (r = −0.68) while rainfall shows only a weak relationship (r = −0.22) which indicates that it has restricted effect on long-term groundwater changes. The results show that human activities which include irrigation needs are the main cause of groundwater depletion in the study area while climatic changes have no impact on this issue which matches results from earlier research studies. The spatial analysis shows specific areas that experience increased depletion because of their use of heavy agricultural methods. The study finds that current groundwater extraction rates cannot be maintained and requires a 25 to 30 percent reduction in pumping to achieve aquifer level stability. The proposed integrated framework provides a scalable, cost-effective, and reliable approach for groundwater assessment especially in regions where data availability is limited and helps decision-makers to manage water resources in a sustainable way.