A method for modeling the effects of climate and land use changes on erosion and sustainability of soil in a Mediterranean watershed (Languedoc, France)

Abstract

Global climate and land use changes could strongly affect soil erosion and the capability of soils to sustain agriculture and in turn impact regional or global food security. The objective of our study was to develop a method to assess soil sustainability to erosion under changes in land use and climate. The method was applied in a typical mixed Mediterranean landscape in a wine-growing watershed (75 km(2)) within the Languedoc region (La Peyne, France) for two periods: a first period with the current climate and land use and a second period with the climate and land use scenarios at the end of the twenty-first century. The Intergovernmental Panel on Climate Change A1B future rainfall scenarios from the Météo France General circulation model was coupled with four contrasting land use change scenarios that were designed using a spatially-explicit land use change model. Mean annual erosion rate was estimated with an expert-based soil erosion model. Soil life expectancy was assessed using soil depth. Soil erosion rate and soil life expectancy were combined into a sustainability index. The median simulated soil erosion rate for the current period was 3.5 t/ha/year and the soil life expectancy was 273 years, showing a low sustainability of soils. For the future period with the same land use distribution, the median simulated soil erosion rate was 4.2 t/ha/year and the soil life expectancy was 249 years. The results show that soil erosion rate and soil life expectancy are more sensitive to changes in land use than to changes in precipitation. Among the scenarios tested, institution of a mandatory grass cover in vineyards seems to be an efficient means of significantly improving soil sustainability, both in terms of decreased soil erosion rates and increased soil life expectancies.

Main Issues for Preserving Mediterranean Soil Resources From Water Erosion Under Global Change

“…The efficiency of conservation agriculture based on no‐till for increasing topsoil SOC and improving soil water storage are well recognized in the Mediterranean region (Moreno et al ., ; Mrabet, ; Alvaro‐Fuentes et al ., ; Jemai et al ., ). Studies conducted on interrow crops such as olive groves (Francia Martínez et al ., ; Gómez et al ., ) or vineyards (Paroissien et al ., ) also support recommendations for noninterrows tillage and for maintaining high interrow vegetation coverage by planting a cover crop or grass. For example, the results obtained from a 4‐year‐long experiment in a Mediterranean vineyard (Herault, South France) provided guidelines for the best interrow management practices that prevent erosion (Figure ).…”

Soil erosion in sloping vineyards assessed by using botanical indicators and sediment collectors in the Ruwer-Mosel valley

“…This botanic benchmark method is based on the measurement of the distance from the topsoil to the grafted vine stock. It has been confirmed as a passive indicator of topsoil movements since the initial planting of vine stocks Paroissien et al, 2015). This method permits the measurement of erosion rates if: i) the temporal scale is long enough to evaluate the accumulated effects of tillage or if tillage is intense enough to show measureable changes in the relief of the plot and ii) sediment redistribution is due to surface wash.…”

Modelling the Hydro‐Sedimentary Dynamics of a Mediterranean Semiarid Ungauged Watershed Beyond the Instrumental Period

“…Land use is one of the key factors on land degradation studies (Paroissien et al, 2015;Serpa et al, 2015;Palazón & Navas, 2016), especially in semi-arid mountainous watersheds (Simonneaux et al, 2015;Buendia et al, 2016). Unfortunately, land use changes are not always successfully implemented in hydrological models (Nunes et al, 2005;de Vente et al, 2008).…”