INTEGRATING FLOOD MITIGATION AND GROUNDWATER RECHARGE IN WATER SCARCE MINING AREA OF SOUTHERN GOBI MONGOLIA

Abstract

The Gobi region of Mongolia, characterized by its arid climate and lack of natural groundwater recharge, is increasingly facing intense flash flood events due to climate change. Despite being a dryland, the area experiences short-duration, high-intensity rainfall events that generate destructive runoff. Compounding this challenge, the region’s mineral abundance is driving rapid growth in water demand, particularly for mining activities. Groundwater remains the sole water source, yet it is unsustainably extracted without natural replenishment. This thesis investigates a nature-based solution: harvesting flash floodwater to support groundwater sustainability through managed infiltration. A Multi-Criteria Decision-Making (MCDM) approach integrated with the Analytic Hierarchy Process (AHP) was applied using nine thematic layers (slope, soil type, land use, lithology, drainage density, lineament density, rainfall, groundwater depth, and runoff potential) to identify suitable zones for floodwater infiltration across a 1,600 km² study area. The Rational Method was employed to estimate the volume of runoff generated during a 5-year return period rainfall event. The analysis revealed that 35.04 km² (approximately 2%) of the total area is highly suitable for infiltration structures. Within this area, an estimated 1,013,256.86 m³ of floodwater can be harvested and redirected into aquifers per event. The findings support the strategic implementation of infiltration-based structures such as retention basins and recharge ponds to mitigate flood damage and enhance groundwater sustainability in climate-vulnerable, water-scarce mining regions.