Wave Climate Along the Nile Delta Coast

Abstract

Directional wave measurements have been carried out at two locations along the Nile Delta coast, and the principal results are reported here. The measurement program commenced in 1985 provides a rational basis for longshore sediment transport and for the design of coastal protection works under extreme wave conditions. Measurement locations at Abu Quir and at Ras el Bar are separated by approximately 190 km. Wave energy conditions have been calculated and characterized on a seasonal basis and for extreme conditions. Due to the prevailing westerly winds, and the relatively limited fetch from the north, the dominant wave direction is from the NW and WNW; whereas, waves from the NNE and NE sectors are limited in magnitude and occur primarily during the summer months. The maximum seasonal significant wave heights at Abu Quir were found to be: 5.5 m, 4.0 m, and 3.3 m for winter, spring and summer, respectively; and at Ras el Bar they were 4.3 m in winter, 2.0 m in spring and 2.6 m in summer. The annual average significant wave height and period were approximately 1.0 m and 6.0 seconds, respectively, at Abu Quir. The corresponding values at Ras el Bar are 0.7 m and 6.0 sec. This smaller wave height at a location with a generally greater fetch has been found to be due to the stronger refraction effects which occur at Has el Bar. The results of this study have been applied to the design of a number of coastal protection structures and to the computation of longshore sediment transport along the Nile Delta coast. At present, consideration is being given to the construction of a coastal road which may also serve for coastal protection. If this plan is implemented, the wave data will play a critical role in the optimization of the set back and protection elements. The paper presents the analysis results for the return periods of extreme waves and the calculated distribution of longshore sediment transport along the Nile Delta coast.