Soil Erosion Assessment and Mitigation Scenarios Based on Geopedology in Northwestern Patagonia, Argentina

Abstract

Transhumant systems related to livestock activity constitute a particular productive land use type that occurs in northwestern Patagonia. Buta Mallín catchment corresponds to summer grasslands, with a significant land use pressure. Soil erosion and mass movement features identified in a geopedological study were applied to landforms to observe the spatial dimension of current processes. About 90% of the area experiences moderate and severe active soil erosion while the remaining 10% remains stable. Areas where gully erosion and soil creep occur correspond to soils derived from volcanic tuff, while sheet and rill erosion processes were evident in soils derived from Holocene volcanic ash. The USLE/RUSLE soil erosion equation was applied to create a map for each parameter of the equation. 85% of the area showed different degrees of potential soil erosion, 76% had moderate and severe hazard and 15% showed no erosion hazard. Mean, maximum and minimum soil loss was 84.2, 299 and 0.5 Tons/ha/year, respectively. Afforestation with conifers and crown closure were simulated and applied in moderately suitable areas, which showed that after 15 years a non-erosion hazard scenario could be reached. The modelling also showed that more than 4000 hectares could be gained for implementing silvopastoral practices without soil erosion hazard preserving transhumant system and reducing more than 30% soil loss. This land use system could allow to obtain timber products as well as make sheepherding lands more productive, reversing land degradation processes.