METHODOLOGICAL COMPARISON IN THE ESTIMATE OF FLUVIAL EROSION IN AN ARID CLOSED BASIN OF NORTHEASTERN PATAGONIA

Fluvial erosion was measured in a closed basin in the arid northeastern Patagonia using the following methods: drainage plots, decrease in capacity of playa-lake-bottom by sediment filling, and Universal Soil Loss Equation (USLE). Although results show a small amount of fluvial erosion, the different methodologies do not explain the observed differences, which would be due to the relative importance that gully erosion has in the area. The erosion plots and the USLE exclude this kind of erosion in their calculation, but it is implicitly considered in playa-lake filling. This means that gully erosion yields approximately 58% of total sediment received by the playa-lake bottom. Comparable values are mentioned by different authors and although the gully density is clearly lower than the maximum reported in the literature, it appears to be an important factor improving the USLE when it is applied to arid rangelands. © 1993 Academic Press. All rights reserved.