Sustainable Drainage Systems and Groundwater Quality in Freetown, Sierra Leone

Abstract

The aim of the study is to examine qualitative relationship between stormwater and groundwater in terms of sustainable drainage systems by taking into account the infiltration ponds as the key point of the design in the Maeba Town, Freetown, Sierra Leone urban catchment. In the first part of the project the quality of infiltrated water from infiltration ponds, which are located in the downstream of the catchment, to soil in terms of Total Suspended Solids, Total Phosphorus and Total Nitrogen analysed for different sustainable drainage systems design scenarios and different physical and geological properties of infiltration ponds. In the second part of the project, three heavy metal pollutants (Iron, Copper and Manganese) are attached the chosen relatively worse design scenario and groundwater quality models are built for the beginning of the rainy season (15.04.2010-15.05.2010) and for yearly (01.01.2010-21.12.2010). The infiltrated water from ponds and their transportation processes in the three-dimensional modelled aquifer are examined and their possible effect on boreholes, which are the main drinking water sources, in the region observed. As a consequence, a general framework is formed about how sustainable drainage systems influence the groundwater quality in the tropical monsoon climate.