- 1Department of Chemical and Geological Sciences, Cagliari State University (UNICA), Cittadella Universitaria di Monserrato, 09042 Monserrato CA, Italy (costantino.pala@unica.it)
- 2Research Institute for the Hydrogeologic Protection – National Research Council (CNR-IRPI) Via 11 Madonna Alta 126, 06128 Perugia, Italy
- 3Department of Geohazards and Climate Change, Geological and Mining Institute of Spain (IGME- CSIC), Ríos Rosas 23, 28003, Madrid, Spain.
- 4Departamento de Geodinámica, Universidad de Granada, Campus de Fuentenueva s/n, 18071 Granada, Spain
- 5Environmental Fluid Dynamics Group, Andalusian Institute for Earth System Research (IISTA), Avda. del Mediterráneo s/n 18006, Granada, Spain
Wildfires are a known treat causing relevant impact on the ecosystem, population and economic infrastructures. They are becoming more and more frequent and severe due to climate changes, and future scenarios are now considering their occurrence into currently fire-resistant areas at higher latitudes. Because of this, the assessment of hazard associated to wildfires require considering also medium to long term effects on the environment. Wildfires induce physical and chemical changes on soil with consequent soil structure losses and formation of water repellent layers. These changes, coupled with canopy cover removal increases runoff and postfire erosion. Enhanced sediment transport is associated with vegetation removal and increased runoff and can remobilize previously deposited material stored in slopes and channels. Moreover, thermal spalling of rocks exposed to wildfire can produce new debris.
Wildfire dramatically changes the degree of Sediment Connectivity: the degree of connection peaks during and just after the wildfire, due to canopy cover removal. Vegetation recovery intermittently changes the degree of sediment connection, affecting the susceptibility to erosion and debris flow likelihood.
As a type case study, we choose the 2021 Montiferru-Planargia (Sardinia) wildfire. We conducted a three-year monitoring of the burnt scar. Immediately after the fire slopes and channels were covered by sparse debris produced by rockfall before the fire and by thermal spalling during the wildfire. Those debris were removed by postfire runoff and involved in postfire debris flows over 33 catchments. Postfire sediment connection changed as vegetation recovered: some catchments were stabilized after one year whereas others experienced debris flow even in the second year. We calculated NDVI over three years at one-month interval and successfully found a NDVI threshold which efficiently represents sediment disconnection induced by vegetation recovery. Our findings are expected to improve erosion susceptibility assessment after wildfire.
How to cite: Pala, C., Melis, M. T., Brunetti, M. T., Pioli, L., Sarro, R., Miranda Garcia, P. V., Galve Arnedo, J. P., and Millares Valenzuela, A.: Vegetation Recovery and Sediment Connectivity in burnt catchments: A case study of the 2021 Montiferru Wildfire Study Case using remote sensing data, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20219, https://doi.org/10.5194/egusphere-egu25-20219, 2025.
