Water resources management in the Medjerda basin (Tunisia): assessment of hydrological impacts of climatic change in the Siliana and Béja catchments

Abstract

Under the current conditions, water resources in Tunisia are intensively exploited and mobilized to meet the increasing demands of all water users. While these resources are limited, approximately estimated to 4,5 Milliards of m3, more than 50% of the total volume of renewable water is withdrawn and mainly used for agricultural purposes (80%). With almost 11 Million of inhabitants, the average of the annual available water volume per person is about 470 m3 which is clearly below the threshold of water scarcity sets to 500 m3/inh/year. Furthermore, water resources are unevenly distributed within the country. About 56% of available waters are surface waters against 44% of groundwater including deep and shallow aquifers. In addition, more than 80% of surface water is mainly from the North, 12% from the center and 8% from the south. One of the most important watercourses in Tunisia is the Medjerda. This river basin covers an area about 23,700 km2 and extends from across the border in Algeria up to the Gulf of Utica (Fig. 1). About 32% of the basin falls within Algeria and 68% in Tunisia (16,100 km2)