USING OF SOME MATHEMATICAL MODELS TO PREDICT THE GROUNDWATER QUALITY AND SOIL PRODUCTIVITY IN EL ARISH VALLEY AREA, NORTH SINAI, EGYPT

Groundwater is considered the main source of water in north sinai at el arish area.the groundwater level withdraw and the salinity of the water increased due to the increasing groundwater discharge and the decreasing of recharge from the rainfall. this study aims at identifying the impact of continuous pumping on groundwater quality and soil productivity in el arish area. historical data of some wells were used to predict the groundwater quantity and quality changes through using modflow and mt3dms models. prediction of groundwater salinity was assessed under three scenarios which considered the increasing of pumping in both absence and occurrence of groundwater recharge from the rainfall. by using the predicted data of groundwater from the model, the soil salinity was calculated by using the equation of fao (198٥) ece = ec * 1٫٥.the calculated values of the soil salinity indicated that the continuous pumping will cause potential increase in water salinity and subsequently the soil salinity will increase. due to the fao standard, the yield of tolerant crops will decrease sharply.