Environmental Implications of Nestos River Damming and Entrenchment – Ecohydrology Solutions for Riparian and Coastal Resoration - 中欧社会论坛 - China Europa Forum

Environmental Implications of Nestos River Damming and Entrenchment – Ecohydrology Solutions for Riparian and Coastal Resoration

Authors: Georgios Sylaios and Emmanuil Koutrakis

Like most river systems, Nestos River, Northern Greece, has undergone significant environmental changes, mainly due to human activities, which adversely affect the river ecosystem that alter habitats and differentiate qualitative and quantitative characteristics of the fish populations. These are: a) changes in the water quality of the river due to point and non-point pollution sources (urban, industrial and agricultural pollution), b) changes in the hydrological status of the system, with the construction of an irrigation (Toxotes, 1966) and two hydroelectric dams (Thisavros and Platanovrisi, 1996) in Greece and an irrigation dam (Despatis, 1967) in Bulgaria that continually regulate the river flow. The combination of all these human impacts leads to the deterioration of the habitat’s quality and the gradual reduction and / or extinction of fish species populations. In parallel, increased erosion rates have been observed along Nestos Delta coastline, ranging from a few centimeters up to 25 m per year. Such phenomenon has been attributed to the entrenchment of Nestos River course along its delta and to the construction of an extensive irrigation system during the early 1950s.

Several EU-funded programs have been implemented along Nestos River, aiming to monitor the above environmental changes and propose the appropriate actions for riparian and coastal restoration. A LIFE-Nature project intended to restore the deltaic configuration at Nestos River mouth, by re-flooding and reconnecting with the main course four old Nestos branches, which were drained after river entrenchment. Interreg IIIA Greece-Bulgaria Project intended to monitor the environmental conditions and the fish fauna populations along Nestos River and its tributaries, aiming to restore the adverse effects produced from river damming and dams operation. These actions included: a) increase of natural fish fauna species stocks that have suffered population decline, b) transfer of broodstocks from upstream to downstream of the dams and vice versa for the species indicated that is necessary to restore the communication between the isolated populations, and c) improvement of the fish fauna natural environment, with actions such as the creation of small, artificial acclimatization basins for juveniles along the river bank.

 

Georgios Sylaios1 and Emmanuil Koutrakis2

1 Democritus University of Thrace, Department of Environmental Engineering, Laboratory of Ecological Engineering & Technology, 67100 Xanthi, Greece.

2 National Agricultural Research Foundation, Fisheries Research Institute, 64007 Nea Peramos, Kavala, Greece.

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