ANTHROPOGENIC IMPACTS ON THE DYNAMICS OF TERGA DUNE IN NORTH AFRICA: CASE STUDY OF ALGERIAN COAST

The Terga Dune located on the Algerian coast is an exceptional morphological unit. It is the basis of important flora, human activities, and plays an essential role in the dynamic balance of the entire southwestern Mediterranean coastal system. The accelerated expansion of the towns especially those in the coastal zone and the accelerated demand of high quality sand for construction engineering have motivated the authorities to set quarries. In Terga beach for example the enterprise which has expanded during the nineties has heavily exceeded the maximum level of extraction allowed by the Algerian mining law.

Neglecting the environmental impacts of the decision of using this non-renewable resource has resulted in the case of Terga, the disturbance of the Maleh River, the deterioration of the original vegetation cover, the overload of surrounding agrarian land by the sand, as well as the emergence of increasing risk on the flooding of Wadi el maleh.

This research explores the dynamic and functional role of dunes and the Bay of Terga in particular, and identifies the human-induced impacts on the Algerian Coast by using historical satellite remote sensing data and meteorological data. Preliminary results from the analysis of historical aerial photos and images before sand extraction (1960/1970), shows a balanced environmental position: stable coast line associated with a homogeneous dune shape and a controlled hydraulic flow of Wadi El Maleh. The comparison with other recent photos (Google and INC) and field data, from 2005 to 2012, indicates a significant degradation caused by extraction of dune sands: widening the bed of Wadi El Maleh, high salt water intrusion in the continental zone, increased occurrences of flooded houses in Terga beach, and desertification farmland behind the dunes.