Groundwater Supply Vulnerability Analysis in the Atoll Islands of the Republic of Maldives in Response to Tsunami Events and Sea Level Rise

Groundwater represents an essential and valuable water resource in small atoll islands in the Indian Ocean. Usually, people in atoll islands communities use hand dug wells to extract groundwater manually from shallow unconfined aquifers through the unsaturated zone. The groundwater is extracted from the lens shaped, and shallow water that floats over more saline seawater. Due to the extreme fragility of the fresh groundwater lens, extracted groundwater is vulnerable depletion due to seasonality of rainfall, or catastrophic fresh groundwater lens pollution due to Tsunami induced overwash events. On the other hand, anthropogenic stresses by human though excessive pumping rates in wet seasons could cause seawater migration landward and temporary salinization of the aquifer as higher pumping rates promotes seawater intrusion. To optimize water supply, efficient integrated water management practices should be enforced and appropriate groundwater extraction rates should be taken into proposed freshwater supply deficit plans. In this presentation, the research findings of a previous work done within this context to quantify threats that could deplete groundwater reserves in atoll islands of the Republic of Maldives reserves are employed to conduct a vulnerability analysis of the future status of fresh groundwater supply for domestic purposes under variety of scenarios (variable rainfall scenarios, sea level rise, overwash events, and population growth) that could deplete freshwater reserves in atoll islands communities. The analysis of the vulnerability of fresh groundwater reserves in the study area concluded that marine overwash events are the most threating environmental stress that can damage fresh groundwater supply significantly within a short time span. In addition, the research recommends that atoll islands communities should adapt management plans to accommodate freshwater supply shortage scenarios including the use of appropriate water sanitation system and reusing domestic greywater after proper treatment particularly for irrigation and toilet flushes to mitigate water shortage crisis.