Hydro-morphological simulation for Blue beach, Gaza Strip, Palestine

Man-made improvements to the coastal areas can have a drastic short- and long-term impact on the sediment balance. This paper investigates the morphological changes at the Blue beach, Gaza Strip, Palestine. The Blue Beach resort is extremely deteriorated due to shoreline recession, where the width of the beach at some locations is less than 0.5 m. On the other side, the new recreational groin is unstable because it is not adequately designed to serve as a breakwater from a technical point of view. Firstly, this paper uses the integrated Digital Shoreline Analysis System (DSAS) with the Geographic Information System to detect changes in the coastline along the Blue Beach coast in Gaza during the 2011–2019 period. Shoreline change rates in the form of erosion and accretion patterns are automatically quantified by the End Point Rate. In addition, a proposed plan consists of two main stages to mitigate the current problems raised by severe erosion through numerical investigation; restoration of the existing beach by sand nourishment in addition to reducing the exposure of the coast to erosion and boost the protection of the recreational groin by implementing submerged offshore breakwaters. Hydro-morphological modeling is applied to study the processes of the coastal zone, hence, evaluating the diverse alternatives mentioned above. Delft3D software package is used to numerically simulate the different scenarios at different times: 1, 5, and 8 years, respectively. In addition, the existing structures are rehabilitated in accordance with current conditions. DSAS results show that during the period (2011–2019) there was a major recession to the shoreline with a peak erosion rate of -4.16 m/year. From the numerical modeling, it is concluded that the two submerged breakwaters managed to restore the beach by minimizing the amplitude of the wave and thus trapping the sediments behind it. In fact, the sediments grew offshore beyond the submerged breakwaters for the long term.