Seawater Intrusion into the Coastal Aquifer in the Gaza Strip: a Computer-Modelling Study

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Journal Title, Volume, Page: 
The Lancet. 12/2013
Year of Publication: 
Reem Sarsak
Environmental Health Department, UN Relief and Works Agency for Palestine Refugees in the Near East, Nablus, West Bank, Palestine
Mohammad N Almasri
Department of Civil Engineering, Faculty of Engineering and Information Technology, An-Najah National University, Nablus. Palestine
Current Affiliation: 
Department of Civil Engineering, Faculty of Engineering and Information Technology, An-Najah National University, Nablus. Palestine
Preferred Abstract (Original): 

Background Climate change is transforming life on earth, as seasons shift, rainfall decreases, and temperatures increase. Rising sea levels and overpumping are causing seawater intrusion into the coastal aquifer. This problem acutely affects people living in the occupied Palestinian territory (oPt), and is worst in the Gaza Strip, where the coastal aquifer is the region's only freshwater resource and is therefore insufficient for the needs of the population. This aquifer has already been degraded by over extraction, infiltration of sewage, and seawater intrusion, contributing to high rates of waterborne diseases in the Gaza Strip. The Israeli authorities tightly control the quantity of water from the aquifer that Palestinians in the Gaza Strip can extract. Palestinians in the oPt receive less than the WHO recommendation of 100 L/day per person. An Israeli citizen uses 250 L/day, whereas a Palestinian citizen uses 66 L/day. Seawater intrusion into the Gaza Strip's northern coastal aquifer was predicted with computer modelling to show the potential effects of climate change and human overuse on the region's only freshwater source.
Methods A simulation of seawater intrusion into the coastal aquifer into the northern part of the Gaza Strip was done with SEAWAT, a computer program developed by the US Geological Survey for simulating the three-dimensional variable density groundwater flow in porous media with multispecies solute transport. This program was used to analyse the groundwater flow and transport, water replenishment rates, and extraction quantities with projected rises in the sea level. The simulation enables prediction of inland seawater intrusion rates and chloride concentrations in the abstraction wells for the next 35 years.
Findings Various scenarios were simulated to study the effects of climate change on seawater intrusion due to rises in the sea level, and variations in replenishment and pumping rates at the study area. The current rate of seawater intrusion into the coastal aquifer is 65 m/year. Computer-modelled scenarios with SEAWAT of future low replenishment rates predict worst-case-scenario intrusion rates of about 80 m/year by the end of the study in 2035. The best computer-modelled prediction of 35 m/year intrusion was obtained with solutions proposed in the management scenario by the local water authorities to reduce the water deficit and remove water salinity in the aquifer.
Interpretation Seawater intrusion can jeopardise the groundwater resources for coastal communities such as those living in the Gaza Strip, putting them at risk of waterborne diseases. The best management of seawater intrusion would be to apply desalination technology and improve the efficiency of existing waste-water treatment plants for water recycling and subsequent reuse. These methods will become increasingly important as climate change negatively affects the aquifer and population demand increases.