EVALUATION OF WATER RESOURCE MANAGEMENT SCENARIOS USING THE WEAP

Abstract

The Oran coastal basin, a semi-arid region in north-western Algeria, is under increasing water pressure due to climate change (rainfall is expected to fall by 10-20% by 2050) and exponential demand for water, particularly from agriculture (70% of abstractions). With a population of 3 million and a demographic growth rate of 1.8% per year, the region already has a structural deficit of 660 million m³ (2023), exacerbated by the over-exploitation of groundwater (-40% since 2000) and losses of 35% in irrigation networks. These challenges call for an urgent overhaul of water management to avert a humanitarian and ecological crisis. Using the WEAP model, this study simulates the evolution of supply-demand imbalances over 30 years (2023-2053), integrating climatic, hydraulic (15 aquifers, 10 desalination plants) and socio-economic data. Of the seven scenarios tested, the most effective combines moderate population growth and sustainable agricultural practices, significantly reducing unmet demand. However, the projections reveal a critical increase in demand (1.89 billion m³ in 2053) and an annual deficit of 2.4 billion m³, exacerbated by the scarcity of rainfall and urban expansion. These results underline the ineffectiveness of supply-side solutions (dams, desalination) in the face of integrated management that prioritises demand. For resilient and equitable management, the study proposes multi-dimensional measures: adoption of technologies (drip irrigation, IoT to reduce losses), progressive pricing with subsidies for vulnerable households, and strengthened governance via basin committees. Social equity is central, requiring priority access to water in rural areas and awareness-raising campaigns. Aligned with MDG 6, these recommendations provide an operational framework for decision-makers, although their implementation depends on up-to-date data and a lasting political commitment. This work illustrates the urgent need for a transition to adaptive management in arid regions, where water remains a matter of survival and justice.