12. Evaluation of Hydrogeological Models and Big Data for Quantifying Groundwater Use in Regional River Systems

The balanced utilization of water resources is necessary to manage the global water cycle. Hydrogeological models capturing complex interactions of all the spheres of the earth are indispensable for effective strategy formation by a better knowledge of the temporal water cycle patterns with due consideration of environmental changes. In large watersheds, groundwater management and its influences on the surface water systems and the hydrological processes are significant. To account for the interactions of groundwater and to ascertain their consequences on the hydrological responses in large watersheds, integrated models are implemented. This chapter explores the combined use of process-based hydrological models and finite element method to improve groundwater management in regional watersheds comprising multiple cities. The study aims to modify basin-scale hydrogeological model, SWAT-FEM to simulate groundwater use in interconnected regional river systems by combining them with big data-based methodical approaches of statistical and mathematical modeling. Such studies are essential to quantify the significant impact of contaminant transport on groundwater use and other groundwater responses in the natural and anthropogenic conditions in river basins. The negative impacts of anthropogenic activities suggested seasonal reduction of groundwater use in the summer months and a significant rise in the winter months. The annual mean groundwater use in the Chennai basin was predicted as 3.18 mm which is well within the safe groundwater abstraction rate of 4.9 mm. The study results would help reinforce and monitor the extremity of groundwater fluctuations prevalent in the study areas through the combined model systems.