RESUMEN
In Mediterranean catchments, such as the Sorraia catchment in Portugal, it is expected that climate change will increase drought stress and the deterioration of water quality in reservoirs. Sustainable land management (SLM) practices are seen as an adaption measure for those problems, but the effectiveness on improving climate change impacted water availability and quality on catchment scale is still poorly understood. Therefore, this study aims to evaluate the effectiveness of SLM practices in adapting the impacts of climate change on water availability and quality of the Montargil and Maranhão reservoirs in the Sorraia catchment. A well-calibrated Soil Water Assessment Tool model is used to simulate four scenarios (2041-2071 and 2071-2100; representative climate pathways 4.5 and 8.5), to investigate the effects of climate change on total phosphorus load (TP) in streams, reservoir volume, irrigation use and water exploitation index (WEI). Results showed that WEI will not exceed any water stress level while reservoir water quality will worsen. In particular since the TP load in streams flowing into the reservoirs increases and the volume decreases, it is likely that the existing P limitation for eutrophication will be counteracted. Nevertheless, tested SLM practices were able to decrease the TP load in those streams and increase the reservoir volume under future climates. Overall, this study shows that the SLM practices are effective in adapting to the climate change effects regarding reservoir water quality, without worsening the water availability; thus, it is a promising tool that should be investigated further for application by e.g. local land-users and decision makers.
RESUMEN
The paper attempts to document the ontology of socio-hydrological systems (SHSs), propose approaches of delimitation of SHSs' (territorial) boundaries, and investigate operational aspects of their adaptation to drought including repercussions on sustainability. To this end, a series of hypotheses are tested: (a) SHSs contain social subsystems with different expectations regarding water resources, different adaptive capacities, adaptation limits and prospects of sustainability, (b) SHSs do not adapt homogenously; some of their subsystems manage optimum adaptation, others fail to adapt and (c) territorial transformation of SHSs (e.g., through expansion of SHSs) may be the result of differential adaptation and sustainability potential within the SHS owing to power relations. After testing above hypotheses in the SHS of Messara Plain, Crete, the authors found out that powerful and dynamic sub-SHSs expand or break the boundaries of the initial SHS by establishing new relationships with other SHSs for the sake of resilience resources. Conversely, powerless sub-SHSs incapable to adapt descend and disappear. Therefore, territorial transformation of SHSs comes about from a combination of successful and failed adaptations, or in other words from different adaptation limits within SHSs. Consequently, water management and local development planning to guarantee adaptability to drought for all should be based on SHSs' analysis and management, not on jurisdictional areas or hydrological basins.