Environmental drivers of dynamic soil erosion change in a Mediterranean fluvial landscape

Abstract

Background Rainfall and other climatic agents are the main triggers of soil erosion in the Mediterranean region, where they have the potential to increase discharge and sediment transport and cause long-term changes in the river system. For the Magra River Basin (MRB), located in the upper Tyrrhenian coast of Italy, we estimated changes in net erosion as a function of the geographical characteristics of the basin, the seasonal distribution of precipitation, and the vegetation cover. Methods and findings Based on rainfall erosivity and surface flow and transport sub-models, we developed a simplified model to assess basin-wide sediment yields on a monthly basis by upscaling the point rainfall input. Our calibration dataset of monthly data (Mg km-2 month-1, available for the years 1961 and 1963–1969) revealed that our model satisfactorily reproduces the net soil erosion in the study area (R2 = 0.81). For the period 1950–2020, the reconstruction of an annually aggregated time-series of monthly net erosion data (297 Mg km-2 yr-1 on average) indicated a moderate decline in sediment yield after 1999. This is part of a long-term downward trend, which highlights the role played by land-use changes and reforestation of the mountainous areas of the basin. Conclusion This study shows the environmental history and dynamics of the basin, and thus the varying sensitivity of hydrological processes and their perturbations. Relying on a few climatic variables as reported from a single representative basin location, it provides an interpretation of empirically determined factors that shape active erosional landscapes. In particular, we showed that the most recent extreme storms associated with sediment yield have been characterised by lower cumulative rainfall, indicating a greater propensity for the basin to produce sediment more discontinuously over time.

Assessment of current reservoir sedimentation rate and storage capacity loss: An Italian overview

“…Most of these papers have investigated the denudation rates, rather than the sediment yield, using different approaches. Such studies of soil erosion in Italy were done recently for five experimental plots in southern Italy (Porto et al, 2022), Valchiavenna valley across Mera river (Maruffi et al, 2022), Basilicata Region (Gioia et al, 2021), Turano basin (Borrelli et al, 2014), Magra River Basin (Diodato et al, 2022), Oltrepo Pavese basin (Bosino et al, 2022), Tronto river in southern Marche region (Bufalini et al, 2022) and lake Iseo (Rapuc et al, 2022). The knowledge about sediment yield in Italy is rather scarce and only a few have investigated reservoir sedimentation.…”

A framework for modelling emergent sediment loss in the Ombrone River Basin, central Italy

“…This has allowed the identification of concepts for the development of parsimonious modelling solutions for sediment load assessment of river systems [44][45][46][47]. Given the issue of assessing erosive sediment by complex models in recognition of the detailed input for the historical period, we arranged a parsimonious erosion model adapted to the annual scale from the original algorithms of Foster et al [48] and Thornes [49] because they provide an interpretation of empirically determined factors shaping active erosional landscapes in basin areas based on the parsimonious balance between driving and resisting forces in the sediment budget [50,51]. The driving forces are essentially simplified to proxies or indicators or rainfall and runoff erosivity associated with splash and transport erosion, respectively.…”

“…The driving forces are essentially simplified to proxies or indicators or rainfall and runoff erosivity associated with splash and transport erosion, respectively. This simplification seems to be adequate for the generation of basin-wide annual outputs, while it may not be fully applicable for the generation of monthly outputs, as seasonal effects become prominent due to the concurrence of rainfall erosivity with different seasonal conditions of soil erodibility [50,51]. Resisting forces are expressed as an exponential function of the fraction of vegetation cover in the basin, as erosion rates show a steep decay compared to that of a bare soil as plant cover increases [52].…”

Predicting soil erosion potential under CMIP6 climate change scenarios in the Chini Lake Basin, Malaysia

“…Besides, misconduct in agricultural practices, tree logging, and building construction speed up the erosion process (Vijith et al 2018 ). Therefore, a suitable condition not only induces soil erosion but also affects to cause flash floods (Diodato et al 2022 ). To mitigate those issues, soil scientists have used a geographical component for the model to obtain the significant causatives for soil erosion (Rodrigo-Comino et al 2018 ).…”