Numerical Evaluation of Community-Scale Aquifer Storage, Transfer and Recovery Technology

Communities in the coastal regions of south-western Bangladesh currently experience severe seasonal water scarcity and groundwater sources of unsuitable salinity. Aquifer storage, transfer and recovery (ASTR), using a seasonal surplus of potable water, is being tested as a potential low-cost (less than $8000 USD) water supply alternative for these communities. A variable-density numerical groundwater model was developed to investigate the engineering technical feasibility of small-scale ASTR systems for the coastal communities in Bangladesh and specifically to support future field site selection and system design. The numerical model was calibrated based on an existing ASTR site and applied to explore the influence of a range of hydrogeological and engineering design parameters. Simulations showed that the water extracted from the ASTR system was able to meet the Bangladesh Drinking Water Standard for Total Dissolved Solids of 1 g/L when injection head or aquifer transmissivity was maximized. A generic ASTR model was developed to examine systems in a non-site-specific context. This analysis showed that four injection wells distributed around a central extraction well with system parameters configured to produce a single injection well plume diameter 1.5 times greater than the level of dispersivity in the system led to high recovery efficiencies regardless of other site characteristics such as injection rate, aquifer depth, and effective porosity