Abstract
Drought temporal characterization is a fundamental instrument in water resource management and planning of basins with dry-summer Mediterranean climate and with a significant seasonal and interannual variability of precipitation regime. This is the case for the Lower Guadiana Basin, where the river is the border between Spain and Portugal (Algarve-Baixo Alentejo-Andalucía Euroregion). For this transboundary basin, a description and evaluation of hydrological drought events was made using the Standardized Precipitation Index (SPI) with monthly precipitation time series of Spanish and Portuguese climatic stations in the study area. The results showed the occurrence of global cycles of about 25–30 years with predominance of moderate and severe drought events. It was observed that the current requirements of ecological flows in strategic water bodies were not satisfied in some months of October to April of years characterized by severe drought events occurring in the period from 1946 to 2015. Therefore, the characterization of the ecological status of the temporary streams that were predominant in this basin should be a priority in the next hydrologic plans in order to identify the relationships between actual flow regimes and habitat attributes, thereby improving environmental flows assessments, which will enable integrated water resource management.
Highlights
The hydrographic basins located in regions with typical hot-summer Mediterranean climate conditions [1] have very hot and dry summers that are similar to summers of semi-arid climates along with mild and humid winters
The characterization of the ecological status of the temporary streams that were predominant in this basin should be a priority in the hydrologic plans in order to identify the relationships between actual flow regimes and habitat attributes, thereby improving environmental flows assessments, which will enable integrated water resource management
The Standardized Precipitation Index (SPI) at these time scales reflects long-term precipitation patterns and are usually tied to streamflows
Summary
The hydrographic basins located in regions with typical hot-summer Mediterranean climate conditions [1] have very hot and dry summers that are similar to summers of semi-arid climates along with mild and humid winters. A management strategy in the hydrological plans is the characterization and modelization of the seasonal and interannual variability of droughts that have occurred in past periods in these basins with Mediterranean climate conditions This knowledge will be fundamental for the establishment of medium-term and long-term governance guidelines that guarantee the availability of water resources and the compatibility of the different uses and the environmental flows in the case of future drought events [5,6]. In this Algarve-Baixo Alentejo-Andalucía Euroregion there is a clear need for all the water uses and environmental requirements to be made compatible and, for this reason, the European Union is promoting, through cross-border cooperation projects, actions aimed at achieving three dimensions of sustainable development: social, economic, and environmental [20] In this context, the modelling and assessment of the past drought periods in this international basin is a fundamental factor for the balanced allocation of all water uses and their compatibility with the environmental flows. Hydrological Plans [21,22]
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