Temporal dynamic of soil erosion and rainfall erosivity as geoindicators of land degradation in Northwestern Argentina.
by
José Busnelli
Institute of Geosciences and Environment (INGEMA). School of Natural Sciences. National University of Tucumán. Argentina.
Coauthors: Liliana Neder and José Sayago (Institute of Geosciences and Environment (INGEMA). School of Natural Sciences. National University of Tucumán. Argentina).

The Northwestern Argentina displays a severe land degradation resulting from centuries of overgrazing and unrestricted cultivation under an aggressive climate, highly fragile loessic soils and strong relief contrasts.

In this work, the soil erosion dynamic (gully and ravine erosion) is evaluated by multitemporal aerial photointerpretation (during the interval 1970-2000) in two different regions, the Western Chaco Plain under wet-dry sub-tropical climate and the pre-andean intermountain valley of Tafí, under semiarid- cold conditions. In addition, the influence of the rainfall erosivity expressed by the “R” factor of the Universal Soil Loss Equation (USLE) was assessed in the same temporal interval. The data were stored and managed using the Geographic Information System ILWIS 3.1.

The results display a significant relationship between soil erosion and the pluviometric dynamic. Therefore, there is a clear response of gully and ravine growing to the increase or decrease of rainfall erosivity.

The Western Chaco Plain has a clear pluvial increment between 1970 and 1978, resulting a greater rainfall erosivity and longer gullies and ravines, accented by deforestation and uncontrolled agricultural activities. During 1978 to 2000, the gully and ravine length increased, but in a lesser way, because the pluvial precipitation decrease.

Tafí del Valle shows the same behavior in response to the climate variations. However, this area has lower rainfall erosion values than the Chaco plain, so that the high increment of the soil erosion is explained by bigger slope steepness and the spread distribution of the loessic materials.

In a few words, the climate is not the only environmental factor influencing the erosion increase, but also the vegetation coverage, human practices, relief, and soils types.

Date received: November 18, 2004

Copyright © 2004 by the author(s). The author(s) of this document and the organizers of the conference have granted their consent to include this abstract in Atlas Conferences Inc. Document # caod-25.