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.