Model-based scenarios of water use in two semi-arid Brazilian states

Sustainability-oriented water management calls for scenarios of future water use. Model-based qualitative-quantitative scenarios combine the development of story lines and the quantification of driving forces with the application of a water use model. In order to support regional planning in two semi-arid Brazilian states suffering from water scarcity, the water use model NoWUM was applied to derive two reference scenarios of municipality-specific sectorial water uses (irrigation, livestock, household, industry and tourism), and to assess the impact of certain interventions. Until 2025, the extension of irrigation accounts for almost 80% of the additional water withdrawals and for an even higher fraction of consumptive use in both scenarios. Domestic and industrial use increases in regions with high immigration, but water use intensities can be controlled by appropriate water pricing. A significant improvement of the developed scenarios is only possible if better data on water use and its driving forces become available.