Impact économique de la protection des sols à l’amont des bassins sur l’agriculture irriguée à l’aval. Analyse par l’approche Target MOTAD
New Medit, Vol 12, n. 1, (March 2013), pp. 57-64.
Jel classifications: Q27, Q24, C61
For the implementation of the Tunisian strategy for soil and water conservation, several management programs have been launched on upstream watershed to reduce erosion, increase rain-fed agriculture productivity and improve local population income.
The potential impact of these programs on the economic benefits of activities and environmental liability in the downstream area are generally ignored. In this study, a hydrological model has been coupled to an economic optimization model (Target MOTAD).
It is designed to simulate, in the case of Merguellil watershed, the potential impact of different scenarios of upstream erosion reduction on the farmers’ returns in the plain, located in the downstream area. The plain is irrigated from groundwater aquifer which is naturally recharged with runoff water from the upstream. The scenarios simulated envisage erosion reduction by 25%, 50% and 75% compared to its maximum level. Results show that all the simulated scenarios reduce the economic returns of farmers in the plain; that becomes particularly high beyond the erosion reduction by 50%. They also show that income gains obtained upstream, resulting from soil conservation and water harvesting, can only partially compensate the economic losses in the plain; this leads to a decrease in the total economic income across the basin (upstream and downstream). Therefore, reducing soil erosion in the upstream watershed seems to be the most appropriate management strategy.
erosion reduction, economic income, losses, gains, upstream, downstream