GROUNDWATER QUALITY DEGRADATION AS A RESULT OF OVERPUMPING IN THE DELTA WADI EL-ARISH AREA, SINAI PENINSULA, EGYPT

The delta Wadi El-Arish area of the Sinai Peninsula is one of the most important parts of Egypt for industrial and agricultural expansion pr ojects because of its relatively abundant supply of groundwater. This study focuses on the hydrogeology and hydrochemistry of the Quaternary aquifer in the delta Wadi El-Arish area and on the impacts pumping ha s had on groundwater quality. The objectives were to determine the rel ationships between groundwater pumping and water levels and water qual ity, to estimate the hydraulic parameters of the Quaternary aquifer, a nd to determine the hydrochemistry of groundwater in the Quaternary aq uifer and its suitability for irrigation. The conclusions are: (1) pot entiometric surface elevations have declined by an average of about 0. 5 m since 1981 in response to an increase in pumping, (2) the transmis sivity of the lower Pleistocene calcareous sandstone (kurkar) unit is higher than the transmissivity of the upper Pleistocene alluvium, (3) groundwater in the Pleistocene aquifer is augmented with groundwater l eaking from the overlying Holocene sand dune deposits through the inte rvening sandy clay aquitard, (4) groundwater in the kurkar is of lower quality than groundwater in the alluvium, (5) total dissolved solids (TDS) concentrations have increased by an average of about 1500 ppm si nce 1962, (6) an increase in saltwater intrusion has occurred in the n orthern part of the study area, and (7) the irrigation suitability of groundwater pumped from wells in much of the area is limited to salt t olerant crops. Our recommendations are: (1) no new pumping wells shoul d be drilled and no increase in pumping rates should be allowed in the delta Wadi El-Arish area, (2) reliable estimates of the quantity of g roundwater recharge should be made, (3) flood irrigation systems shoul d be replaced by either drip or sprinkler systems, and (4) the operati on of wells should be managed by automatic control systems.