NILE DELTA IN ITS DESTRUCTION PHASE

All deltas undergo alternating construction to destruction phases due to fundamental changes in the relative influence of sediment input fro m rivers and redistribution by marine coastal processes. During the pa st 7000 years world deltas, including the Nile, have been in an overal l construction phase. However, the Nile delta has converted to a destr uction phase during the past 150 years, triggered by water regulation which has disrupted the balance among sediment influx, erosive effects of coastal processes, and subsidence. This former depocenter has been altered to the extent that it is no longer a functioning delta but, r ather, a subsiding and eroding coastal plain. Symptoms of the destruct ion phase of the Nile delta include accelerated coastal erosion and st raightening of the shoreline, reduction in wetland size, increased lan dward incursion of saline groundwater, and buildup of salt and polluta nts to toxic levels in wetlands and delta plain. Without seasonal flus hing by floods, the former delta plain surface is now incapable of rec ycling and/or removing agricultural, municipal and industrial wastes g enerated by Egypt's rapidly expanding population. Moreover, the remain ing capacity of the system to regenerate itself will further diminish as water is diverted away from the delta for new irrigation and munici pal projects in the Egyptian desert, and water allocations to Egypt ar e decreased by upstream countries. Reestablishing some level of natura l hydrology is the only credible solution for attaining equilibrium am ong sediment accretion on the delta plain to offset subsidence, progra dation along the coast to offset erosion, and sufficient water influx to flush and remove the high levels of salt and pollutants throughout the system. However, increased Nile water and sediment discharge could begin to restore a functioning delta system only if there is a substa ntial reduction in human impacts.