Modeling of seawater intrusion in the coastal aquifer: A case study of Bosaso Plain in Somalia

Seawater intrusion is process that damage groundwater quality in the coastal regions. Groundwater overexploitation in the Bosaso Plain has resulted in seawater intrusion problem. Groundwater modelling were considered to study the effects of possible seawater intrusion into the Bosaso Plain. In this study, we present a three-dimensional variable–density numerical model developed with the SEAWAT code, which is aimed to predict the extent of seawater intrusion by different groundwater pumping scenarios. Results revealed the higher concentration of electrical conductivity (EC), total dissolved solids (TDS), chloride, sodium, calcium and magnesium along the coastal area which indicated the presence of seawater intrusion in the study area. The SEAWAT model was calibrated using both the average value of heads and TDS concentration for the 2013 field data. Four scenarios were simulated to understand the effects of pumping and climate change to the extent of seawater intrusion for a period of 27 years. The model results show that seawater intrusion significantly affects the groundwater concentrations near the coastline and demonstrated high levels of TDS. The predicted results reveal that increasing pump rate seawater intrusion interface will move about 6.2 km inland by 2040. Results also revealed that a 50% reduction in the pump rate will bring relief to the aquifer by protecting fresh groundwater and preventing any further seawater intrusion. Key Words: Groundwater modeling, seawater intrusion; coastal aquifer, SEAWAT Bosaso Plain, Somalia.