JOINT INTERPRETATION OF GEOPHYSICAL, HYDROGEOLOGICAL, AND GEOINFORMATICS DATA TO EXPLORE SUBSURFACE WATER BEHAVIOUR IN A GARHWAL HIMALAYA WATERSHED, INDIA

Abstract

The Himalayan watersheds are located within the Himalayan mountain range, which is characterized by unique geology, complex hydrology, and unstable geo-dynamical features. The watershed plays a crucial role in regional hydrology where surface water and groundwater are intricately entwined and function as unified resources. The subsurface water supplies in the region are especially crucial for communities downstream and also contribute to rivers, springs, and streams in the form of base flow. The steep topography of the Himalayas results in rapid runoff from precipitation events, leading to the formation of numerous rivers and streams. These water bodies interact with groundwater through processes such as infiltration, recharge, and baseflow, shaping the hydrological dynamics of the region. he Himalayas are characterized by complex geological structures, including folded and faulted rock formations, which create diverse hydrogeological conditions. Variations in rock types, fault lines, and structural features influence the movement and storage of groundwater that is responsible for discontinuous aquifers in the region. Groundwater in the Himalayas is stored in various types of aquifers, including fractured rock aquifers, alluvial plains, and glacial moraines that lead to complexity and the formation of aquifers is not well understood. The aquifers' properties, such as permeability, porosity, and storage capacity exhibit in a wide range that controls the extent of groundwater-surface water interaction and it is challenging to understand. The Himalayan region experiences distinct wet and dry seasons, with monsoonal rainfall that play a significant role in water availability, however complex dynamic geology and the growing freshwater demands of ever-increasing population influence groundwater recharge rates and aquifer storage capacities.