Modeling the effect of chemical fertilizers on ground water quality in the Nile Valley aquifer, Egypt

Chemical fertilizer use in Egypt has increased significantly since the construction of the Aswan High Dam in 1968, Increased applications of chemical fertilizers in irrigated lands are likely to create nonpoint contamination sources of chemical fertilizer species. This study was conducted to investigate the contamination of ground water by nitrogen and phosphorus chemical fertilizers, as well as the availability of ground water for irrigation and public water supply for the next century. Future concentrations of NO3-, and PO43- in shallow and deep ground water in the Nile Valley were assessed under realizable rates of fertilizer application. A ground water modeling system (GMS) was used to simulate the three-dimensional ground water flow and contaminant transport in the Tahta region of the Nile Valley Aquifer, and to predict the future concentrations of chemical fertilizer species, Results of the transport simulation predict the occurrence of ground water contamination at shallow depths (30 m) due to the high rate and method of chemical fertilizer applications. Best management practices should be employed to control and reduce the nitrate leaching and future impact of phosphorus and potassium fertilizer applications. At the same time, new deeper wells should be constructed. In addition, the use of hand pumps, in zones close to croplands (15 m depth) must be avoided due to susceptibility to fertilizer contamination, Ground water from existing deep wells can be used as an alternative water supply Furthermore, a ground water quality monitoring system should be established for early detection of ground water contamination and to determine progress of the fertilizer contaminant plume, A properly designed system should monitor nitrate and phosphate composition in observation and water supply wells.