Don River Delta hydrological and geomorphological transformation under anthropogenic and natural forcings. Dynamics of delta shoreline, risk of coastal flooding and related management options

We studied hydrological and geomorphological transformations in the Don River Delta, South Russia, due to river engineering and climate change over century and decadal time scales and how these transformations affect integrated coastal zone management (ICZM). The most eastern and one of the largest of Mediterranean-Black Sea delta basins, the Don River Delta is under-represented in international studies. The impacts river runoff (RR), fluvial sediment delivery (FSD), waves and marine surges on changes in the migration of the delta front (DFM) were assessed. There were several major river changes beginning with the construction of the Tsimlyansk dam in 1952. FSD decreased dramatically from 1933 until the present and the Delta changed its functional state from river-dominated to wave-dominated starting in the mid 1990s. Annual maximum water height (MHA) in the center of the Delta increased in variability and amplitude from the mid-1980s and was more influenced by strong marine surges as a result of more frequent westerly winds. Climatically-induced surges interacting with waves caused increased erosion of the delta front, but brought in high levels of resuspended marine sediments. FSD was statistically positively related to DFM by the end of the 20th century. DFM was statistically positively related to MHA by the end of the 1990s. We assessed the risk of coastal flooding caused by more frequent and stronger surges over the last forty years on economic damage for the settlements in the Don Delta. We conclude that ICZM for the Don Delta is needed now because urban population growth increases exposure to more frequent coastal flooding in the Delta and recent changes of DFM negatively influence protected areas. A coastal management plan to address erosion and flooding is a first step of ICZM of the Don Delta.