Soil erosion elasticity initiative for prioritizing sub-watersheds

Abstract

Quantitative evaluation of soil erosion is necessary to analyze the destructive effects of soil erosion and to identify priority sub-watersheds in different climatic and environmental conditions. The variability of soil erosion thresholds introduced as Erosion elasticity (Ee) can be used to develop reliable management strategies in various temporal and spatial scales. Ee is a potential degree of soil erosion in an area representing the magnitude between maximum and minimum erosion rates. However, the comprehensive prioritization of sub-watersheds according to environmental changes and the concept of Ee is yet to be done. Therefore, the present study introduced the Ee-based approach based on the watershed's maximum and minimum soil erosion capability. The prioritization of the sub-watersheds of the Shazand Watershed of Iran has been exemplified, and the associated results were compared to those of conventional annual soil erosion zoning. Towards that, the mean annual soil erosion and corresponding changes of the study watershed were estimated according to the dynamic changes of vegetation cover and rainfall erosivity. Prioritizing 24-study sub-watersheds was then comparatively conducted using mean annual soil erosion and erosion elasticity approaches. The results of the RUSLE application showed that the soil erosion of the Shazand Watershed varied between 0 and 72 t ha⁻¹ year⁻¹ with a mean annual erosion of 14.35 t ha⁻¹ year⁻¹. The results further revealed that the worst and the best combination of soil erosion factors cause +151% and −62% changes in mean annual soil erosion of the Shazand Watershed. Based on the amount of soil erosion method, sub-watersheds 11, 14, and 23 were placed in the highest priorities, and sub-watersheds 5, 6, 16, and 17 are the lowest priority for management measures. In addition, the results of the Ee approach showed that 28% of the study sub-watersheds were placed in high and relatively high priorities, respectively, and sub-watersheds 9, 13, 18, 19, and 23 stand in the lowest priority. The Ee approach effectively identified the critical sub-watersheds to reduce their tendency to destructive conditions and take appropriate measures to reduce their soil erosion and move them towards ideal conditions. The results can help planners and managers implement the best management measures in priority sub-watersheds, saving time and cost.