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Descripción
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| A recent study has shown that annual maximum daily rainfall will increase in the future because of climate change in several regions of Spain, according to climate projections provided by EURO-CORDEX. This study aims at understanding how the expected changes in precipitation extremes will affect the flood behaviour in the future. In Spain, floods are usually generated by rainfall. However, for a given rainfall event, the flood magnitude also depend on the initial moisture content in the catchment, which in turn also depends on precipitation and temperature in the days before its occurrence. Therefore, the expected changes in precipitation extremes cannot be transformed directly into changes in runoff. Hydrological modelling is required to characterise the rainfall-runoff process adequately in a changing climate to estimate flood changes. For hydrological dam safety, the risk of dam overtopping is given by the maximum water elevation reached during the routing process. The complexity of the routing process in a reservoir requires a representation of the full hydrograph. Consequently, not only the flood peak is the variable of interest, but also the flood hydrograph volume. This paper aims at finding how expected precipitation changes in the future will affect the magnitude of both flood peaks and hydrograph volumes. Four catchments located in central western Spain have been selected as case studies. The HBV hydrological model has been calibrated, using the observed precipitation, temperature and streamflow data available at a daily scale. Daily rainfall and temperature projections for RCP 4.5 and 8.5 provided by EURO-CORDEX have been used, after correcting the bias. Finally, change rates or deltas have been calculated for a set of variables that describe a flood hydrograph: quantiles of flood peak and cumulative volumes in one, three, five and seven days. Finally, streamflow series supplied by the calibrated HBV models under climate change scenarios have been used as inflow at the reservoirs located at the outlet of the four catchments considered, in order to quantify the impact of climate change on hydrological dam safety. As the four dams have controlled spillways, the Volumetric Evaluation Method has been used to account for how gates are operated. The results have shown that the correct calibration of some parameters of the HBV model is essential to obtain coherent results, mainly those related to surface runoff generation. In addition, soil moisture content at the beginning of flood events influences on flood magnitudes. Consequently, expected changes in precipitation extremes are usually smoothed by the reduction of soil moisture content due to expected increases in temperatures and decreases in mean annual precipitation. In addition, differing results are obtained depending on the climate model considered. Consequently, uncertainty due to differing climate model outputs is accounted for in the delta changes obtained for flood peak and volume hydrograph quantiles for a set of return periods. | |
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Internacional
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Si |
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Nombre congreso
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International Conference on Natural Hazards and Risks in a Changing World |
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Tipo de participación
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970 |
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Lugar del congreso
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Potsdam, Germany |
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Revisores
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Si |
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ISBN o ISSN
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DOI
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Fecha inicio congreso
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04/10/2018 |
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Fecha fin congreso
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05/10/2018 |
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Desde la página
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96 |
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Hasta la página
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96 |
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Título de las actas
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International Conference on Natural Hazards and Risks in a Changing World. Book of abstracts |