Impact of River Damming and River Diversion Projects in a Changing Environment and in Geomorphological Evolution of the Greek Coast

Abstract

It has been observed, in many Mediterranean countries, that human activities-engineering works, such as large dams and reservoirs construction (hydroelectric power dams, irrigation dams and water supply dams), artificial river diversion projects, channelization, etc., may seriously affect the environmental balance of inland and coastal ecosystems (forests, wetlands, lagoons, Deltas, estuaries and coastal areas). Dam constructions and their operation has modified the natural evolution trends of coastal areas to a considerable extent and has arguably been the most important factor controlling the evolution of the Greek coastal zone in recent decades. While an important factor of the destabilization of the ecological balance is the "climate change", the role of "climatic cycles" is not negligible. Dams and reservoirs retain vast masses of water and sediments, thus adversely affecting water resources, the seasonal hydrological and hydrogeological regimes, while this disruption of water flow and sediment transport is able to generate changes on the supply of groundwater aquifers, on the emerging coastal erosion phenomena and consequently impacts on delta evolution and coastal ecosystems. Also, the creation of artificial lakes in forest areas and deforestation, contribute to increase emissions of CO2 and other greenhouse gases and climate change. The purpose of this study is to: a. describe the main man-made interferences (engineering works) which due to their nature and position, cause changes in the natural evolution of the hydro-geomorphological processes in the deltaic coastal zone of the rivers Nestos, Acheloos, Arachthos, Louros, Spercheios, Inois and Alfeios, in Greece, b. report a synthesis of the environmental and geomorphological studies of the areas under study, c. describe the geomorphological evolution of the selected areas and d. detect and evaluate the impacts of the above mentioned anthropogenic activities and the influence of "climate change" and affect the geomorphological evolution of the Greek coast.