Spatial distribution of geomorphic changes after an extreme flash-flood compared with hydrological and sediment connectivity
- 1Inter-University Institute for Local Development (IIDL), Department of Geography, University of Valencia, Valencia, Spain (adolfo.calvo@uv.es)
- 2Biology of plants under Mediterranean Conditions (http://plantmed.uib.es/Ingles/index.html), Department of Biology, University of the Balearic Islands, Palma, Spain (xurxogago@gmail.com)
- 3Institute of Agro-Environmental and Water Economy Research –INAGEA, University of the Balearic Islands, Palma, Spain (joan.estrany@uib.cat)
- 4Mediterranean Ecogeomorphological and Hydrological Connectivity Research Team (http://medhycon.uib.cat), Department of Geography, University of the Balearic Islands, Palma, Spain
- 5Service of GIS and Remote Sensing, University of the Balearic Islands, 07122 Palma, Balearic Islands, Spain (maurici.ruiz@uib.es)
- 6Universitat Politècnica de València, Camí de Vera, s/n, València, 46022, Spain (beanacro@cam.upv.es)
An extraordinary flash-flood event occurred the 9th October 2018 in the north-eastern part of Mallorca Island. The spatial distribution of main geomorphic changes were accurately mapped through field and aerial UAV campaigns in two contrasted small headwater catchments (i.e., < 2 km2) of the Begura de Saumà River. The first one was massively covered by step terraces over Lias limestone, whilst the second one was only covered by check-dam terraces over Miocene marls.
Two weeks after the event, a UAV was used to record aerial photographs and build high-resolution digital elevation models (HR-DEM; i.e., 5 cm). Geomorphic changes were assessed comparing this HR-DEM with LiDAR-derived DEM (i.e., 25 cm resolution) obtained in 2014. The Borselli index of connectivity (IC; version of Cavalli et al., 2013) was calculated from the LiDAR-derived DEM to compare the geomorphic changes triggered by the flash-flood with the structural sediment connectivity distribution.
At hillslope scale, the HR-DEM allowed the identification of geomorphic changes, such as the initiation of rills and the wall collapse of old agricultural terraces in the terraced limestone catchment. In the main headwater valley axis of the marls catchment, where natural streams had been historically reduced and deviated with the construction of check-dam terraces, huge geomorphic changes enabled the recovering of natural streams.
The spatial distribution of the observed geomorphic changes on hillslopes was compared with the spatial patterns of sediment connectivity. Geomorphic changes elucidated a good concordance with structural connectivity, both in the location and magnitude. The analysis of these concordances and some discordances allows the identification of hydrogeomorphological factors triggering the erosional response of hillslopes.
This work was supported by the research project CGL2017-88200-R “Functional hydrological and sediment connectivity at Mediterranean catchments: global change scenarios –MEDhyCON2” funded by the Spanish Ministry of Science, Innovation and Universities, the Spanish Agency of Research (AEI) and the European Regional Development Funds (ERDF).
How to cite: Calvo-Cases, A., Gago, J., Ruiz-Pérez, M., García-Comendador, J., Fortesa, J., Company, J., Nácher-Rodríguez, B., J. Vallés-Morán, F., and Estrany, J.: Spatial distribution of geomorphic changes after an extreme flash-flood compared with hydrological and sediment connectivity, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21687, https://doi.org/10.5194/egusphere-egu2020-21687, 2020
How to cite: Calvo-Cases, A., Gago, J., Ruiz-Pérez, M., García-Comendador, J., Fortesa, J., Company, J., Nácher-Rodríguez, B., J. Vallés-Morán, F., and Estrany, J.: Spatial distribution of geomorphic changes after an extreme flash-flood compared with hydrological and sediment connectivity, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21687, https://doi.org/10.5194/egusphere-egu2020-21687, 2020
