An assessment and mapping of groundwater potential zones in the Darjeeling Himalayan region using frequency ratio and analytical hierarchy process

The groundwater crisis is spreading across India at an alarming rate, and it poses a serious threat to the existence of the living world. However, the nature of scarcity is uneven and spread to some unexpected locations, such as the Darjeeling Himalayan region, where rainfall is adequate. Darjeeling Himalaya, one of the most attractive tourist destinations in India, is facing a water crisis due to adverse topographical characteristics, climatic issues, and over-exploitation along with rapid urbanization, booming tourism industry, excessive deforestation, and climate change, which are making the situation progressively worsening. Consequently, a huge imbalance is generated between the requirements and availability of water, which promotes the black-marketing of water and has flourished in the entire region. For this reason, the assessment of the groundwater potential zone and its distribution in the Darjeeling Himalayan region become very important. In this regard, eight thematic maps are prepared with the help of geospatial techniques and integrated with frequency ratio and analytical hierarchy methods to prepare a groundwater potential map of the study area. The final map is reclassified into five potential zones, i.e., very low, low, moderate, high, and very high classes, respectively. The results of this analysis show that the success rate and prediction rate of the FR model are 87 and 83%, respectively. On the other hand, success and prediction rates for AHP methods are 84 and 79%, which indicates the performance of the FR method is slightly better than the AHP method. The overall result may be helpful to planners in better management or sustainable use of groundwater resources.