Al Makha is an ancient and important port in Yemen. It is
confronted with a dramatic shortage of fresh water supply because of
groundwater contamination by sea water intrusion. To study this
problem, two dc-resistivity methods, vertical electrical sounding
(VES) and two dimensional 2D resistivity imaging surveys, have been
conducted. Ten VES-es were preformed in the alluvial plain area and
four 2D-resistivity profiles were conducted in the coastal strip near the
shore line.
Interpretation of the collected resistivity data, correlating with
water depth and electrical conductivity measurements revealed the
presence of two water bearing horizons, the upper is correlated to
medium to coarse-grained sands intercalated with clay, extends from
the surface to 30 and 85 m depth with average thickness of 50 m. The
lower is correlated to medium to fine-grained deposits extends to
about 250 m below the mean sea level. A combined surface resistivity
and hydrochemical data indicate invasion of the Red Sea water into
the lower alluvial aquifer. The saline water saturated zone is shallow
near the shore line and goes deeper inland. The depth to the top of
saline water intrusion is about 10-m at 2-km distance from the shore
and increased to 150 m at 10 km. Also, it extends in a zigzag line
parallel to the shore line depending on the morphology of the
seawater, subsurface geology, and rate of pumping. Water table
contours of the aquifer showed that the groundwater flow does not
have a definite direction but it depends on the abstraction rate over the
area.