Climate change and transboundary water management in the Tunisian Mellegue Catchment

Human activities and climate change affect hydrological and sedimentological characteristics within catchments. For arid and semiarid areas this induces direct negative economic and environmental consequences on society. In fact, stability in the rainfall regime and less siltation trapped in reservoirs mean more water for irrigation, water supply, and better flood control. This is especially important in the Tunisian semiarid region where water needs are close to potential water resources and siltation is reducing the reservoir capacity rapidly. Wadi Mellegue was chosen in order to study trends of water resources availability. Linear regression modelling and Mann-Kendall tests were performed for trend analysis. The study dealt with rainfall, discharge, and sediment patterns in the catchment area during a 44-year period. The results display a common decline in rainfall depth at different time scales. However, a positive trend related to discharge and siltation process was found. An increase in vulnerability to the new climate conditions is described. Consequently, water resources and agricultural landscape management for the Mellegue catchment should be revised in order to ensure a sustainable up- and downstream catchment development.