Deciphering groundwater potential zones using integrated approach of remote sensing, GIS, and AHP in a reservoir-induced seismicity (RIS) region in western India

This study aims to decipher groundwater potential zones using an integrated approach of remote sensing, geographical information system, and analytical hierarchy process in the Koyna-Warna region of western India, an area affected by the reservoir-induced seismicity (RIS). This region serves as a key example of the RIS, primarily due to the construction of the Koyna dam in 1964. The filling of the reservoir water behind the dam has been associated with a significant increase in seismic activity, particularly in the surrounding area. This seismicity is thought to be triggered by the weight of the water, which induces stress on the Earth’s crust, leading to the faults slipping. Moreover, the groundwater potential zones in this region are crucial for understanding the dynamics of seismic events. Thus, multiple important factors affecting groundwater such as geology, geomorphology, soils, land use and land cover, slope, lineaments density, drainage density, rainfall, normalized vegetation index, and topography wetness index were considered for deciphering the groundwater potential zones. Spatially distributed thematic layers of all these factors were generated using remotely sensed data and ground-based data in GIS platform. The assigned weights of all these layers and their attributes were then normalized by using analytical hierarchy process technique. The deciphered groundwater potential zones of this RIS area were categorized as very good (15.68%), good (27.34%), moderate (29.25%), poor (19.54%), and very poor (8.19%). These assessed groundwater potentialities were positively correlated with the well specific yields with a correlation coefficient of R = 0.90, and was found reasonable. It was also observed that the very good to good potential zones were in the upstreams. Most of the very good groundwater potential zones (~ 16.79%) were found in the northern part, namely Koyna region (which was more the seismically active) than the Warna region (~ 14.57%) located in the southern part. It indirectly indicated that the groundwater potentially also induced the seismicity of earthquakes along with both Koyna and Warna reservoir waters. The deciphered groundwater potential zones in this RIS area will aid in better study of the earthquake seismicity in future.