Assess and mapping the flooding hazards using geospatial tools and empirical model along Kenitra coast, Morocco

Abstract

This study assesses the coastal flooding risk of Kenitra coast (Morrocan Atlantic) consisting of rectilinear beaches backed by dunes and crossed by the mouth of Sebou river. A Differential Global Positioning System (DGPS) topographic survey of the study area was carried out in order to analyse shore and backshore morphology. Total water levels (TWL) are empirically calculated and statistically analysed, taking into account the tide data, wave runup and projection IPCC sea level rise. The TWL estimation method is adapted taking into account the differences of coast morphology: natural beaches exposed directly to the Atlantic waves, and sheltered urban areas protected by a dike inside the Sebou estuary. Projections of extreme TWL on topography of the study area were performed in order to map floodable areas. The results show that the Kenitra coast is not secured against the risk of coastal flooding during extreme storms. The most vulnerable areas are located near the jetties of the mouth north of Mehdia beach and south of Chlihat beach. The extension of flooded areas is between about 402 500 m2 and 647 900 m2 for the 25 and 100 years water levels, respectively. However, the operations of sand nourishment and reprofiling beach in these low areas can protect backshore from expected risk of storm surges.