Development of an empiric model of estimation of the environmental risk of soil physical degradation in the context of climate change application in the Mejerda valley, Tunisia

Abstract

Land degradation is a serious environmental problem. Soil physical degradation is the consequence of several factors including topographic, edaphic and agronomic characteristics as well as climatic factors.Soil quality assessment is of main interest. Therfore an empirical model was developed to estimate the environmental risk of soil physical degradation in the context of climate change within homogeneous hydrological units of a middle valley Mejerda watershed and to study the interaction between climate change and soil degradation risk.This approach is based on the usual formula expressing the environmental risk and the usual matrix operation for data processing. Six scenarios for different return periods are simulated in order to study the interactive changes between climatic hazards and soil vulnerability in each unit.Three risk degradation classes are distinguished based on the result of the elaborated model (Risk, Vulnerability, and Hazards).Units in low slopes and cultivated with olive trees have low risk (3, 58 × 104 < risk <14, 54 × 104), while units in average slope and cultivated with cereal have a medium risk (5,09 × 104 < risk< 18,23 × 104). However, high slope units (slope > 33%) are the riskiest ones (6, 36 × 104 < risk <21,94 × 104).Soil degradation risk is assumed to be proportional to vulnerability matrices that depend on topographic, edaphic and agronomic characteristics and climatic hazard matrices which depend on rain characteristics.The elaborated model seems to be applicable to other watersheds of Tunisia, constituting a tool for soil conservation planning and structural management.