Steep-mountain hillslopes are increasingly affected by natural hazards such as landslides and soil erosion due to a more frequent occurrence of extreme hydrometeorological events. This study aimed to i) detect changes in the erosion of a hillslope in the Bridge Creek Catchment (BCC, eastern Italian Alps), and ii) characterize the tracer signature of overland flow (OVF) from eroded hillslopes in comparison to other water sources (stream water, spring water, groundwater and saturated riparian zone) within the catchment. High-resolution Digital Surface Models (DSMs) were reconstructed using Unmanned Aerial Vehicle (UAV) photogrammetry to characterize and quantify the spatial sediment removal (erosion) or deposits on the experimental hillslope of BCC. In addition, the hillslope was monitored using monthly-captured pictures from June 2023 to May 2024 to investigate rill formation. The DSMs analysis (comparison between August 2023 and April 2024) shows that the average depth of the erosion along the rill networks was estimated as 5.2 cm (Area 1) and 2.9 cm (Area 2). Regarding the characterization of the water sources using environmental tracers (i.e., δ2H and δ18 O, electrical conductivity and major ions), preliminary results show that the isotopic signatures of various water sources-such as stream water, groundwater, spring waters-exhibit a depletion in heavy isotopes compared to summer rainwater. However, the isotopic signature of OVF had an isotopic composition similar to rainwater, unlike the other water sources sampled in the catchment. In general, combining high-resolution UAV surveys with geochemical tracer investigations can help to better understand hillslope hydrological and erosion processes, including quantifying the amount of erosion or deposition. Furthermore, in the future our results could provide adequate information to develop effective mitigation strategies in the upper Cordevole catchment, aiming at a restoration of vegetation on eroded hillslopes using nature-based solutions.
Erosion Dynamics and Tracer-Based Characterization of the Water Sources in an Alpine Catchment
Adane, Girma Berhe;Marin, Enrico;Marchina, Chiara;Bettella, Francesco;Martini, Marco;Zuecco, Giulia
2024
Abstract
Steep-mountain hillslopes are increasingly affected by natural hazards such as landslides and soil erosion due to a more frequent occurrence of extreme hydrometeorological events. This study aimed to i) detect changes in the erosion of a hillslope in the Bridge Creek Catchment (BCC, eastern Italian Alps), and ii) characterize the tracer signature of overland flow (OVF) from eroded hillslopes in comparison to other water sources (stream water, spring water, groundwater and saturated riparian zone) within the catchment. High-resolution Digital Surface Models (DSMs) were reconstructed using Unmanned Aerial Vehicle (UAV) photogrammetry to characterize and quantify the spatial sediment removal (erosion) or deposits on the experimental hillslope of BCC. In addition, the hillslope was monitored using monthly-captured pictures from June 2023 to May 2024 to investigate rill formation. The DSMs analysis (comparison between August 2023 and April 2024) shows that the average depth of the erosion along the rill networks was estimated as 5.2 cm (Area 1) and 2.9 cm (Area 2). Regarding the characterization of the water sources using environmental tracers (i.e., δ2H and δ18 O, electrical conductivity and major ions), preliminary results show that the isotopic signatures of various water sources-such as stream water, groundwater, spring waters-exhibit a depletion in heavy isotopes compared to summer rainwater. However, the isotopic signature of OVF had an isotopic composition similar to rainwater, unlike the other water sources sampled in the catchment. In general, combining high-resolution UAV surveys with geochemical tracer investigations can help to better understand hillslope hydrological and erosion processes, including quantifying the amount of erosion or deposition. Furthermore, in the future our results could provide adequate information to develop effective mitigation strategies in the upper Cordevole catchment, aiming at a restoration of vegetation on eroded hillslopes using nature-based solutions.
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