The groundwater table in four districts of Jeddah city in Saudi Arabia is to be lowered by installing a sub-surface drainage system. In connection with the drainage studies, the suitability of the drainage water to irrigate recreational areas within the City was evaluated. If reuse was not feasible, the pollution potential of the drainage water for discharge to the coastal waters had to be determined.
Quality of the sub-surface waters in the areas to be drained was characterized as follows: Physical parameters (temperature and turbidity); chemical parameters (pH, total dissolved solids, salinity, conductivity, ammonia nitrogen, chemical oxygen demand, and the major cations of calcium (Ca++), magnesium (Mg++), potassium (K+) and sodium (Na+) and anions of sulphate (SO,--) chloride (Cl-), bicarbonate (HC03-) and nitrate (NO,-); and, bacteriological parameter (fecal coliforms). Samples were collected from 31 shallow (3-5m) and from 4 deep observation wells (40-86 m).
The study showed that the quality of the drainage water was highly saline and was not suitable for irrigation. However, the quality satisfied the standards of the Meteorology and Environmental Protection Agency for discharge to the Red Sea.