Files
Abstract
Water resources become increasingly scarce, scarcity that will become acute in the coming years
due, among others, to a reduction in water supply, as a result of climate change, and the increase
in demand, accentuated by the population increase and the requirements of economic growth and
development. In this context of scarcity, Morocco is confronted with the need to adapt its water
management policy from a supply management to a demand management one. Implementing
such a policy requires the adoption of new policy instruments and decision making support tools
that take into account the complexity of the current and future situation, as well as allowing the
assessment of the economic, social and environmental impacts of various water resources
allocation alternatives at the overall river basin level. This paper compares several methods for
calculating the water value and proposes an integrated economic water management model at the
river basin scale. This model takes into account the economic, institutional, hydrological and
agricultural aspects, as well as the behavior of various agents involved in water resources
management and the competition among sectors. One Major contribution of this model is a
detailed disaggregation by spatial units (hydrological units, cropping areas, and grazing land), by
agricultural production systems (irrigated and rainfed crops), and by farm sizes. Basically it’s an
optimization model with a non linear objective function, and using the positive mathematical
programming method technique for its calibration. Given the conjunctive use of water at the
river basin level, the model results show the tremendous impact of surface water management on
the overexploitation of the ground water and the risk of its depletion. A management policy of
surface water based on administrative pricing, pumping cost, and water supply marginal cost is
proven inadequate for a sustainable resource management since it underestimates the overall
water scarcity at the river basin level.