Agriculture Management and Hydro-geological instability

Hydro-geological instability (HGI) threatens soil health and human safety. Agriculture management and HGI are tightly interconnected, especially under the effect of climate change. The increasing frequency and intensity of extreme weather events expose many areas to strong hydro-geological risks, with special emphasis to the mediterranean environments. Hydro-geological risk occurs through flooding, landslides (gravity-driven mass movements of soil), gully and rills erosion (concentrated runoff of soil) and diffused/sheet erosion, and water stagnation, exposing natural and cultivated ecosystems, and human settlements to dramatic management problems. Soil erosion can vary depending on soil characteristics and weather, and can account for 10-50 t sediment lost ha-1 year-1 or even more. Because it affects large areas, human-induced erosion can be more marked than erosion driven by weather events at the landscape scale. Soil loss is commonly estimated with the Universal Soil Loss Equation (USLE) based models, which considers rainfall erosivity (R), soil erodibility (K), slope length and steepness (LS), and cover-management practices (CP). Management mainly affects CP, which can dramatically increase or reduce the total erosion in agriculture. In Agriculture, tillage and harvest operations strongly trigger soil degradation and the sheet erosion, escalating the other forms of erosion. Tillage destroys soil structure, damages vegetation cover, triggers the formation of gullies or rills. In particular, shifting from tillage to no tillage reduce erosion by 70-95%. Reduction of forest cover and unregulated urban expansion often blocked water infiltration in soil and increased its speed, which increased the erosion potential.