Measurement of soil erosion on different spatial scales with vegetation cover of caatinga in the northeast of Brazil

摘要

Erosion is a phenomenon whose impact on renewable natural resources has been worrying governments and institutions in different parts of the world. To this effect, this study aimed to generate and analyze information obtained in the field, involving the main processes and sources of variation in soil-loss data on different spatial scales in a semi-arid region with a vegetation cover of native caatinga. The study area is located in the semi-arid region of the state of Ceara in Brazil, in the watershedof the upper Jaguaribe River. Studies of erosion and runoff were conducted on three different levels: a watershed with an area of 2.06 ha, an erosion plot of 20 m2 and a plot of 1 m2, all under natural-rainfall conditions. The vegetation of the study area is made up of native caatinga. The study was carried out from 2009 to 2011, with rainfall concentrated in the period of January to June, corresponding to the rainy season in the region. The highest coefficients of runoff were recorded on the scale ofthe 20m2 plot in relation to the scales of 1m2 and the watershed, with the exception of 2009. The highest soil loss in the first two years studied occurred in the watershed in relation to the 20m2 scale. These results were due to the special characteristics of the watershed, where there are places of high sediment yield, these barely being found on the scale of the smaller plot. The transfer soil-loss data measured for small plots, to larger scales cannot be made in a linear fashion.