@article{AichLierschVetteretal.2015,
  author    = {Aich, Valentin and Liersch, Stefan and Vetter, Tobias and Andersson, Jafet C. M. and M{\"u}ller, Eva Nora and Hattermann, Fred},
  title     = {Climate or Land Use?},
  series = {Water},
  volume    = {7},
  journal   = {Water},
  number    = {6},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {2073-4441},
  doi       = {10.3390/w7062796},
  pages     = {2796 -- 2820},
  year      = {2015},
  abstract  = {This study intends to contribute to the ongoing discussion on whether land use and land cover changes (LULC) or climate trends have the major influence on the observed increase of flood magnitudes in the Sahel. A simulation-based approach is used for attributing the observed trends to the postulated drivers. For this purpose, the ecohydrological model SWIM (Soil and Water Integrated Model) with a new, dynamic LULC module was set up for the Sahelian part of the Niger River until Niamey, including the main tributaries Sirba and Goroul. The model was driven with observed, reanalyzed climate and LULC data for the years 1950-2009. In order to quantify the shares of influence, one simulation was carried out with constant land cover as of 1950, and one including LULC. As quantitative measure, the gradients of the simulated trends were compared to the observed trend. The modeling studies showed that for the Sirba River only the simulation which included LULC was able to reproduce the observed trend. The simulation without LULC showed a positive trend for flood magnitudes, but underestimated the trend significantly. For the Goroul River and the local flood of the Niger River at Niamey, the simulations were only partly able to reproduce the observed trend. In conclusion, the new LULC module enabled some first quantitative insights into the relative influence of LULC and climatic changes. For the Sirba catchment, the results imply that LULC and climatic changes contribute in roughly equal shares to the observed increase in flooding. For the other parts of the subcatchment, the results are less clear but show, that climatic changes and LULC are drivers for the flood increase; however their shares cannot be quantified. Based on these modeling results, we argue for a two-pillar adaptation strategy to reduce current and future flood risk: Flood mitigation for reducing LULC-induced flood increase, and flood adaptation for a general reduction of flood vulnerability.},
  language  = {en}
}
@article{VogelPatonAichetal.2021,
  author    = {Vogel, Johannes and Paton, Eva and Aich, Valentin and Bronstert, Axel},
  title     = {Increasing compound warm spells and droughts in the Mediterranean Basin},
  series = {Weather and climate extremes},
  volume    = {32},
  journal   = {Weather and climate extremes},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {2212-0947},
  doi       = {10.1016/j.wace.2021.100312},
  pages     = {14},
  year      = {2021},
  abstract  = {The co-occurrence of warm spells and droughts can lead to detrimental socio-economic and ecological impacts, largely surpassing the impacts of either warm spells or droughts alone. We quantify changes in the number of compound warm spells and droughts from 1979 to 2018 in the Mediterranean Basin using the ERA5 data set. We analyse two types of compound events: 1) warm season compound events, which are extreme in absolute terms in the warm season from May to October and 2) year-round deseasonalised compound events, which are extreme in relative terms respective to the time of the year. The number of compound events increases significantly and especially warm spells are increasing strongly - with an annual growth rates of 3.9 (3.5) \% for warm season (deseasonalised) compound events and 4.6 (4.4) \% for warm spells -, whereas for droughts the change is more ambiguous depending on the applied definition. Therefore, the rise in the number of compound events is primarily driven by temperature changes and not the lack of precipitation. The months July and August show the highest increases in warm season compound events, whereas the highest increases of deseasonalised compound events occur in spring and early summer. This increase in deseasonalised compound events can potentially have a significant impact on the functioning of Mediterranean ecosystems as this is the peak phase of ecosystem productivity and a vital phenophase.},
  language  = {en}
}