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Summary: In this study we analyzed the response of monthly runoff to precedent climatic conditions at temporal scales of 1–48months in 88 catchments of the Ebro basin (northeast Spain). The standardized precipitation evapotranspiration index (SPEI) was used to summarize the climatic conditions at different time scales, and was correlated with the standardized streamflow index (SSI) calculated at the mouth of each catchment. The Ebro basin encompasses a gradient from Atlantic to Mediterranean climates, and has remarkable complexity in topography, geology and land cover. The basin is highly regulated by dams, which were built to produce hydropower and supply water for agriculture. These characteristics explain why sub-basins of the Ebro River basin respond in differing ways to precedent climatic conditions. Three main sub-basin groups were distinguished on the basis of the correlation of their streamflow responses to different time scales of the SPEI: (1) sub-basins correlated with short SPEI time scales (2–4months), which generally corresponded to unregulated headwater areas; (2) sub-basins correlated with long SPEI time scales (10–20months), where groundwater reserves play a major hydrological role; and (3) sub-basins correlated with medium SPEI time scales (6–10months). The latter occur in the lower sectors of the Ebro basin and its tributaries, which receive river flows from the other two sub-basins, and where dam regulation has a significant influence on the hydrological characteristics. In addition to the three main sub-basin groups, other streamflow responses associated with seasonal factors were identified, particularly those related to snowpack and the various management strategies applied to reservoirs. [ABSTRACT FROM AUTHOR]

Abstract: To evaluate the vulnerability of agriculture under Mediterranean conditions, the real water needs of agriculture in the Fluvià watershed (Catalonia, NE Spain) were estimated for the XXIst century using a combination of downscaled climate projections (ECHAM5 plus MM5) in two IPCC scenarios (B1 and A2), watershed hydrological model (SWAT) and FAO procedure to calculate crop potential evapotranspiration. In comparison with baseline conditions (1984–2008), climate projections predicted a 12% (B1) to 28% (A2) reduction in precipitation, and a 2.2°C (B1) to 3.6°C (A2) increment of mean annual temperature at the end of the XXI Century (2076–2100). The changes of the environmental conditions would affect the real water availability in different crops: water required for irrigation would increase significantly along the century, ranging from 40 to 250% depending on the crop, because of a direct decrease in the amount of water available along the growing season and because of the effects of the projected climatic conditions on potential evapotranspiration (ET0) and on the phenology of these crops. Results are showing the high sensitivity of agriculture, despite its expanding technology, to changes in climate, and even more to site, plot, orchard or terroir conditions. [Copyright &y& Elsevier]

Summary: A methodology to analyze impact, vulnerability and adaptation to climate change in conjunctive-use systems at basin scale is presented. Based on the value obtained for various indices under possible future scenarios (indices obtained from the results of a system management model), a systematic procedure is presented to identify problems and solutions to adapt to climate change effects. The future hydrological scenarios to be analyzed can be approached by starting from the historical series available for the system and taking into account the changes expected in the key statistics of the series. A method to predict the expected changes in the key statistics using the results of previous climate change studies in the area has been developed. A “downscaling” procedure is proposed to translate the climatic variations into results on a basin scale. The methodology has been applied to the case study of the Serpis River Basin (Eastern Spain). [ABSTRACT FROM AUTHOR]