Modelling artificial infiltration through the vadose zone in the unconfined coastal aquifer of Dar Es Salaam (Tanzania): a preliminary assessment for a managed aquifer recharge (MAR) solution

Abstract Groundwater is an essential source of freshwater worldwide. In urban and peri-urban areas of Sub-Saharan Africa cities, such as Dar es Salaam (Tanzania), the scarcity of good quality surface water has led to the overexploitation of the aquifer, due to the growing demand for water linked to the demographic and economic development of the city. This has also caused the phenomenon of saltwater intrusion degrading the quality of groundwater resources. In addition, rapid urban expansion and the consequent increase in impermeable areas, hindering infiltration, have led to a reduction in groundwater recharge with significant water table decrease. This study explores the potential of managed aquifer recharge (MAR) as a sustainable solution for integrated water resource management by assessing their suitability in selected areas of Dar es Salaam City. The infiltration process has been modelled with SEEP-W software, considering different basins with embankments and two scenarios: a constant head water volume given by a flooding event and a high intensity precipitation event inducing the storage of rainfall water. The results show that MAR can represent a useful tool for integrated water resource management in the study area with the potential to effectively enhance groundwater sustainability and contributing to more resilient urban water systems in the city.