The role of fringing coral reef in beach protection of Hurghada,Gulf of Suez,Red Sea of Egypt

摘要

The coral-reef system fronting most of the coastline of the Red Sea provides natural protection to the aquatic system.Its pronounced morphologic features protect coastal recreation facilities located behind the reef.To provide a basis for evaluating the role of the fringing coral reef in protecting marinas and sandy beaches against waves and currents,a two-dimensional (2D)numerical model "SIMulating COastal PROcess"(SIMCOPRO)was applied with its three main modules including wave,current and sediment.The selected study area is located at Sahl Hasheesh coast south of Hurghada on the west coast of the Red Sea at a site proposed for the construction of a marina.The model offers insight in how the reef system modifies the wave and current fields.The application of the model in the presence of a marina reveals insignificant erosion on the downdrift side of the marina breakwaters (south of the southern breakwater).The erosion is expected to be 1 m after the first year,2 m after the next 5 years and no further change for a period of 10 years.This is because the rocky reefal beachface will be exposed and erosion of sand will be diminished.The minor local erosion is controlled by the protective response of coral reef,the very limited coarse sand on the beachface (<0.5 m thick),the weak current induced by waves (0.13 m/s)and other topographic protective elements in the region.The submerged/emerged geometric nature of the reefal system,both reef fiat and reef crest,allow wave dissipation and thus behaves as a submerged breakwater to protect marinas or artificial beaches in the shelter zone of this reef.An important lesson to be learned from this study is that improper construction practices of building marinas can seriously hurt the environment.The dredging of artificial reef lagoons is one improper practice that would create unexpected beach erosion.