Seawater intrusion caused by unmanaged groundwater uses in a coastal tourist area, Cox’s Bazar, Bangladesh

The Cox’s Bazar region at the southeastern coast of Bangladesh has been gradually changed from a rural settlement into a densely populated urban area, caused by the rapid growth of tourism. Water demand is mainly covered by groundwater, and the hotels and resorts are typically operating their own groundwater wells without metering and regulations. In this study, the temporal and spatial variations in groundwater quality and hydraulic heads in the Cox’s Bazar area were evaluated over a period of 2 and 4 years respectively, to analyze the effects of the groundwater extractions on the status of the groundwater resources. Due to the pronounced seasonality of rainfall, the aquifer system was found to be highly dynamic even without human interference and seawater intrusion into the aquifers from the Bay of Bengal as well as from the Bakkhali river in the north was detected. The groundwater abstraction caused groundwater levels in some touristic centers to be already permanently below sea level, and a trend to a further lowering of hydraulic heads was observed. This coincides with an overall trend of increasing electrical conductivities in the groundwater. For a sound and sustainable development of the Cox’s Bazar region, water management strategies and a regulatory framework have to be developed that consider the specific conditions in such a coastal zone.