Sandbehov för att motverka stranderosion utmed Skånes sydkust under perioden 2017–2100 / Estimation of required beach nourishment volumes along the south coast of Sweden during 2017–2100

Beach erosion is expected to increase as the sea level rises during the coming decades. A retreating coastline threatens infrastructure, settlements, nature habitats, and at the same time increases the flood risk in low-lying areas. On the Swedish south coast, beach erosion is a problem at present likely to increase due to the sea level rise. For maintaining the beaches and protecting the hinterland, beach nourishment is generally the preferred method. Cost effective and environmental friendly beach nourishment projects are dependent on marine borrow areas for sand. Outside the Swedish south coast there are several identified suitable marine sand extraction sites. Sand is, however, a limited resource and the construction industry in Sweden has begun to show interest in marine sand as material for concrete production. Therefore, the municipalities along the Swedish south coast need to quantify the expected demand for sand in order to maintain their beaches. A methodology was derived in this study to estimate the sand volume needed to maintain a beach based on the historical coastal morphological evolution and the expected increase in erosion due to sea level rise. The methodology has been applied on the Swedish south coast. Sand volume needed to maintain beaches, for a scenario where the mean sea level rises with 1 meter until year 2100 and including the observed long-term morphological evolution due to gradients in the longshore transport, is calculated to be approximately 44 million m3. The required volume corresponds to 6 % of the potential volume for marine sand extraction in the area. To preserve the sandy beaches for future generations, a minimum of 44 million m3 sand should be earmarked for beach nourishment purposes in the marine spatial plans.