Combined impacts of climate and socio-economic scenarios on irrigation water availability for a dry Mediterranean reservoir.
The impacts of climate and associated socio-economic changes on water availability, including supply and demand, quality, and storage volume, were evaluated for the Vale do Gaio reservoir in southern Portugal, located in a dry Mediterranean climate and already under drought stress. The SWAT model was applied with 6 scenarios for 2071-2100, involving two storylines (A1B and B1) with individual changes in climate (-9% rainfall, increasing in winter by +28 to +30%), socio-economic conditions (an increase in irrigation demand by 11%, and a replacement of cereals and pastures by sunflower), and a combination of both. Most future scenarios resulted in lower water availability, due to lower supply (-19 to -27%) combined with higher irrigation demand (+3 to +21%). This resulted in more years with limited irrigation supplies (presently: 28%; scenarios: 37 to 43%), although limitations were mitigated by lower losses to excess discharge. Land-use changes also decreased quality by increasing P concentrations (+29 to +93%). Impacts were more severe in scenario A1B than in B1, and in combined changes than in climate or socio-economic changes only. Water availability was resilient to climate change, as impacts led only to a moderate aggravation of present-day conditions. Lower future water availability could be addressed by supply and demand management strategies and, in the most extreme scenario, by water transfers from regional water reserves; water quality issues could be addressed through land-use policies. Results also highlighted the importance of taking the characteristics of water supply systems into account when designing adaptation measures for future changes.
CESAM & Dept. Environment and Planning, University of Aveiro. Campus Universitário de Santiago, 3810-193 Aveiro, Portugal; CE3C: Centre for Ecology, Evolution and Environmental Changes, Faculty of Sciences, University of Lisbon. Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa, Portugal. Electronic address: jpcnunes@fc.ul.pt.
João Pedro
JP
Nunes
CESAM & Dept. Environment and Planning, University of Aveiro. Campus Universitário de Santiago, 3810-193 Aveiro, Portugal; IGOT: Institute for Geography and Territorial Management, University of Lisbon. Rua Branca Edmée Marques, Cidade Universitária, 1600-276 Lisboa, Portugal.. Electronic address: ritajacinto@campus.ul.pt.
Rita
R
Jacinto
CESAM & Dept. Environment and Planning, University of Aveiro. Campus Universitário de Santiago, 3810-193 Aveiro, Portugal. Electronic address: jjkeizer@ua.pt.
Jan Jacob
JJ
Keizer
D057914:Agricultural Irrigation; D057231:Climate Change; D011174:Portugal; D012959:Socioeconomic Factors; D014867:Water; D014881:Water Supply
D014867:Water
Climate change; Irrigation water supply; Land-use change; Mediterranean region; Water scarcity