1,2,1,2,1,2,1,2,1,2- 1Centre for the Research and Technology of Agro-Environmental and Biological Sciences (CITAB), University of Trás-os-Montes and Alto Douro (UTAD), 5000-801 Vila Real, Portugal
- 2Institute for Innovation, Capacity Building and Sustainability of Agri-Food Production (Inov4Agro), 5000-801 Vila Real, Portugal
- 3Potsdam Institute for Climate Impact Research (PIK), Member of the Leibniz Association, 14412 Potsdam, Germany
- 4Institute of Environmental Science and Geography, University of Potsdam, 14476 Potsdam, Germany
- 5BIORG—Bioengineering and Sustainability Research Group, Faculty of Engineering, Lusófona University, 1749-024 Lisbon, Portugal
- 6LEAF—Linking Landscape, Environment, Agriculture and Food, Instituto Superior de Agronomia, Universidade de Lisboa, Tapada da Ajuda, 1349-017 Lisbon, Portugal
Southern Portugal is one of Europe’s climate change hotspots. Given its arid climate, droughts in this region are already long and frequent; however, recent studies estimate that their duration and frequency may increase, putting the region’s water availability at stake. Along its western coast lies the Sado River Basin (SRB), a large, entirely Portuguese catchment that is home to some of Portugal's most important agricultural hubs. Hence, considering how important water is in the SRB, and that precipitation events over the SRB may become scarcer, projecting the basin’s future water availability is a must. This study showcases and explores the estimated flow rates (FRs) of the Sado River in southern Portugal, focusing on the projected conditions expected in a near-term future period, between 2041 and 2060. These FRs were projected under the Shared Socioeconomic Pathways: 1–2.6 W/m2 (SSP1–2.6), 3–7.0 W/m2 (SSP3–7.0), and 5–8.5 W/m2 (SSP5–8.5), using downscaled and bias-adjusted General Circulation Model (GCM) ensemble projections from the Inter-Sectoral Impact Model Intercomparison Project (CHELSA-ISIMIP3b-Sado) as input for hydrological simulations with the Hydrological Simulation Program—FORTRAN (HSPF). To our knowledge, this research marks the first time that future climate projections from the 6th phase of the Coupled Model Intercomparison Project (CMIP6) were used as input to hydrological simulations of the SRB. CHELSA-ISIMIP3b-Sado projections have shown increases in temperature, and decreases in precipitation during autumn and spring months. Moreover, the HSPF simulation outputs have projected reductions in the Sado FRs, which could cause decreases in yearly accumulated riverine water volume (29% under SSP3–7.0 and 33% under SSP5–8.5), as well as increases in summer riverine water deficit (31% under SSP3-7.0). In addition, there is a projected increase in the variability of precipitation during the winter months, and as a consequence, meeting surface water demands of the Sado region may be delayed by up to 22 days. Therefore, in the coming decades, winter precipitation could become even more important for the recharge of reservoirs and the fulfilment of summer surface water needs in the SRB. Considering the predominance of the agricultural sector in the region, the results of this research should prompt local agricultural stakeholders and administrative institutions to enhance winter surface water storage and management in order to meet summer crop irrigation demands.
How to cite: Claro, A., Fonseca, A., Fernandes, A., Menz, C., Almeida, C., Fraga, H., and Santos, J.: How will climate change impact Southern Portugal flow rates? A CMIP6-HSPF modelling approach, EMS Annual Meeting 2026, Utrecht, Netherlands, 6–11 Sep 2026, EMS2026-381, https://doi.org/10.5194/ems2026-381, 2026.
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