Modelling seasonal variation of gully erosion at the catchment scale

Abstract

Geo‐hydrological phenomena, including gullies, contribute significantly to soil erosion and land degradation. To address this, proper management of basins and hillslopes should consider the mechanism, timing, and location of gully development and how gullies interact with other hillslope processes. Yet, conventional modelling techniques for such processes are rare, frequently being limited to applications of only single processes and typically requiring high‐resolution input data. Further, existing tools for characterizing basins and hillslopes tend to be based on static descriptions of geo‐environmental conditions, and thus are not effective for modelling changes such as the seasonal triggering conditions of gully phenomena over time. This study proposes a method to integrate open remote sensing data (Sentinel‐2) and an existing modelling tool (LANDPLANER) using simplified input data to better predict and forecast gullies’ spatial and temporal occurrence. The study investigates the seasonal conditions responsible for the triggering of gullies at the catchment scale using different erosion modelling schema in the Toscana region of Central Italy. Geomorphological gully inventory data were collected and used as benchmarks to test the proposed approach. The results show that the occurrence of gully erosion in the studied region changes seasonally, and the proposed method was able to effectively discriminate spatial and temporal differences of the gully phenomena. The proposed method can be applied to similar regions worldwide, allowing for the investigation of gully erosion over time, even in places with limited data availability.

Introduction to the Women in Geomorphology special issue

“…Remote sensing ( 26) Agostini et al, 2022;Atwood & West, 2022;Davies et al, 2022;Davis et al, 2021;Fadul et al, 2022;Gervasi et al, 2021;Hendrickx et al, 2022;Hodge & Buechel, 2022;Hooke, 2022;Hovenga et al, 2021;Konlechner & Hilton, 2022;Lefebvre et al, 2022;Marchetti et al, 2022;McKenzie et al, 2022;Mol & Grenfell, 2022;Opalka et al, 2022;Rabanaque et al, 2022;Regalla et al, 2022;Reitman et al, 2022;Sampietro-Vattuone et al, 2021;Schoch-Baumann et al, 2022;Thompson et al, 2022;Vah et al, 2022;Valentine et al, 2022;Zhang et al, 2022 Physical experiments (8) Bako et al, 2022;Bywater-Reyes et al, 2022;Demiral et al, 2022;Friedrich et al, 2022;Negreiros et al, 2022;Rachelly et al, 2022;Roelofs et al, 2022;Vah et al, 2022 Numerical models ( 11) Agostini et al, 2022;Bywater-Reyes et al, 2022;Cullen et al, 2022;Glover et al, 2022;Hodge & Buechel, 2022;Kooijma...…”

“…Papers addressing process and form in coastal environments include examinations of dune morphodynamics and evolution (Hovenga et al, 2021; Konlechner & Hilton, 2022; Kooijman et al, 2022); the influence of sorting and bedforms on the magnitude of coastal eolian transport (Uphues et al, 2022); coastal changes in response to an extreme storm (Spiske et al, 2022); estuarine mangrove dynamics (Glover et al, 2022) and the morphology of estuarine bedforms (Lefebvre et al, 2022); geotechnical properties of salt marsh soils (Brooks et al, 2022) and tidal wetland development (McKeon et al, 2022); seasonal morphodynamics of intertidal bars (Biausque et al, 2022); and wave impacts and cliff erosion (Thompson et al, 2022). Papers addressing hillslopes and mass movements include interactions between raindrop impacts and particle settling velocities in sheet flow (Bako et al, 2022); a review and synthesis of soil piping (Bernatek‐Jakiel & Nadal‐Romero, 2023); a review of erosion plot studies in the Brazilian Cerrado (Souza Fonseca et al, 2022); seasonal variations in gully erosion (Agostini et al, 2022); influences on Mediterranean badlands formation (Nadal‐Romero et al, 2022); numerical models of landslide effects on the cosmogenic isotope signal of fluvial sediment (Schide et al, 2022); surface slip on strike‐slip faults (Reitman et al, 2022); post‐fire patterns of rock weathering (Mol & Grenfell, 2022); precursory indicators of alpine rockfall (Hendrickx et al, 2022); grain‐size distributions of mass movement deposits (Harvey et al, 2022); influences on landslide initiation based on field observations and numerical modelling (Patton et al, 2022); physical experiments on debris‐flow erosion (Roelofs et al, 2022); and comparison of digital elevation models built from different data sources (Atwood & West, 2022). Glacial geomorphic studies are represented by papers examining topographic controls on ice flow and glacier front recession (Davies et al, 2022); moraine dynamics in the context of climate change (Rowan et al, 2022); and streamlined sub‐glacial bedforms (McKenzie et al, 2022).…”

Achieving change through gully erosion research

“…Simulation capability is also being developed in spatial models of gully erosion physical processes which hold the potential to provide increased specificity in targeting management and in defining management actions. For example, the effects on gully generation of changed climate or surface hydrology can be simulated (Agostini et al, 2022; Hancock & Willgoose, 2021), and the outcomes of specific management options can be explored (e.g., Luquin et al, 2021). However, limited availability of field data has constrained the setting of model parameter values and testing of model predictions, and more research on site hydrology, hydraulics, and soil erodibility is needed (Bennett & Wells, 2018; Douglas‐Mankin et al, 2020; Liu et al, 2021).…”

Modeling of Gully Erosion in Ethiopia as Influenced by Changes in Rainfall and Land Use Management Practices

“…Studies show that topography, soil, climate, and land use/land cover (LULC) can strongly affect the occurrence and distribution of gullies [1,[6][7][8]. The topographic and soilrelated factors are known to have a relatively static influence, while the climate and LULCrelated factors have a dynamic effect on the initiation and expansion of gullies [9,10]. Thus, changes in LULC and climatic elements such as rainfall can highly influence the initiation and relative position of gully heads and, hence, define the spatio-temporal extent of gullies across different climatic regions.…”

“…Third, the applicability of the model was priorly tested in two study areas. The model was tested in dryland and Mediterranean environments across Iran and Italy [6], respectively, considering gullies as point and line features [9,10]. Thus, this study is the first case to apply the model in a sub-humid climate in the tropical region of Africa representing gullies by point and polygon features.…”