Scarcity of fresh water resources in the Ganges Delta of Bangladesh

Abstract

Understanding the interdependency, availability, and accessibility of surface water and groundwater plays a major role in identifying and managing water security. The Ganges Delta in Bangladesh is a classic example of a water insecurity scenario in a transboundary river basin where concerns in quantity, quality, and timing of available water are producing disastrous conditions. This study examines surface water and groundwater uses and demands, seasonal availability, sustainability, and potential water security concerns. Human interventions that can influence seasonal water availability and shifting demands between surface water and groundwater are also examined. Surface water availability was analyzed using streamflow including the effects of upstream water diversions, rainfall, temperature, and evapotranspiration. Groundwater data was collected from 283 locations established by the Bangladesh Water Development Board. Total water storage anomaly data from the GRACE satellite (2002–2016) was analyzed to assess changes in groundwater availability. Both in situ and GRACE data show a significant declining trend in groundwater. Comparisons of groundwater recharge and withdrawal amounts in six different years (1983, 2009–2012, 2015) indicate an unsustainable water withdrawal condition. Irrigation is the largest sector of off-stream water use with total water withdrawal amounting to 31% for surface water and 68% for groundwater. The region’s domestic water use entirely depends on groundwater, which is problematic due to arsenic pollution. This study provides insight into the changes in surface water and groundwater resources and limitations to freshwater availability, thereby encouraging a better management strategy for water resources in the region.