Temporal dynamics of soil erosion and rainfall erosivity as geoindicators of land degradation in Northwestern Argentina

The subtropical region of Northwestern Argentina displays severe environmental deterioration due to a combination of factors, including seasonally contrasting weather, highly erodable loessic soils, a topography with varied slopes, and natural vegetation coverage restricted by deforestation and agricultural advance, in addition to exploitation of natural resources by people. The aim of the present research was to determine the landscape degradation, using as geoindicators the increase in erosion by water and the pluviometric gradient variations through time. Two regions were chosen as sample areas in the province of Tucuman: the eastern foothills and plain of the Southeastern Ranges (Western Chaco); and the intermountain valley of Tafi. Erosion increase was quantified by measuring the length of gullies and ravines; and the sedimentation in the artificial lake (La Angostura) located in the center of the valley of Tafi. Climate changes were analyzed by means of the rainfall erosivity variations in both sample areas during the last 30 years. The lineal increase in erosion is closely related to the pluvial dynamics. Nevertheless, this erosive intensification is also dependent on the interaction of environmental factors and human activities (deforestation, land use changes, unrestricted agriculture). (c) 2006 Elsevier Ltd and INQUA. All rights reserved.