Abstract
Climate change impact on water resources (streamflow and deep natural recharge) based on the downscaled outputs from the ECHAM5 general circulation model (GCM) has been investigated in the Mediterranean basin (Fluvià, Spain) for the A2, B1 greenhouse scenarios and 2000–2024/2025–2050 time slices. The HEC-HMS 3.4 rainfall-runoff numerical model was the basic tool used to generate streamflow for the historical period, and deep natural recharge was calculated from Visual-BALAN 2.0, a water-soil-plant distributed model. The hydrologic and recharge models were employed to generate future climate change hydrographs and the deep recharge amount. Furthermore, the selected future climate scenarios, subject to possible changes in the land use/land cover forecast, were integrated into the models, and water resource impacts were assessed. The multiple combinations of climate model, time slices, greenhouse scenarios, land use/land cover scenarios and hydrological estimation methods resulted in six scenarios. The obtained results estimate an increase in temperature (1.5 °C), a decline in precipitation (17%) and a maximum decrease of 49.5% and 16.8% in runoff and groundwater recharge, respectively, for 2050 (A2) compared to the historical values. Planned land cover scenarios, implying small changes of agricultural and forested land, show no major contribution to future water resource changes. According to the results, the most sensitive parameters conditioning future water resources are changes in temperature and precipitation.
Highlights
Over the last decade, an extensive amount of research has been done on how climate change might influence different aspects of the hydrological cycle in many geographic areas [1,2,3,4,5,6]
According to the output of the current coupled atmosphere-ocean general circulation models (GCMs) for the 2080–2100 time slice [7], an increase in temperature between 1.5 ̋ C and 3.6 ̋ C and a decrease in precipitation between 10% and 20% are forecasted in the western Mediterranean ([8], in accordance with the A1B storyline from ICCP, which describes a balance across all energy sources in the greenhouse effect)
The main objective of this paper is to apply a linked methodological approach to investigate the impacts of climate change on a highly forested Mediterranean hydrological system where a strong surface water-groundwater interaction exists, by taking into account joint effects on flow regime, groundwater recharge and socio-economic scenarios led by land use changes
Summary
An extensive amount of research has been done on how climate change might influence different aspects of the hydrological cycle (precipitation, runoff, evapotranspiration, etc.) in many geographic areas [1,2,3,4,5,6]. The Mediterranean basin is a relatively closed subsystem of the global hydrologic system, where a number of interdependent processes occur with respect to the land-atmosphere interactions and their variability. The climate in the Mediterranean presents a great sensitivity to global change. Climate change projections indicate increased probability of drought [9] and variability in extreme events. Changes in future climate will alter regional hydrologic cycles and will subsequently have an impact on water resource availability [10]
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