Soil erosion is a major global threat affecting billions of people, particularly in developing regions. As the environmental crisis deepens, this systemic threat could increase further, accentuating the socio-economic and environmental vulnerabilities of many countries. Human activities may not alter the fundamental mechanisms of erosion, but they do significantly modify its speed, frequency and intensity. In this context, the Brasília region and the Cerrado savannah offer an essential natural laboratory, not only because of the urgent need to preserve this fragile ecosystem, but also because of the tensions between nature conservation and human development.
The aim of this study was to measure the rates of natural processes, notably denudation and surface lowering, that shape the evolution of the landscape in central Brazil over a long period (103-106 years), and to compare them with the rates of human-accelerated erosion near the capital Brasília over recent decades. To do this, a multidisciplinary approach combining cosmogenic nuclides produced in situ (10Be and 21Ne) and in the atmosphere (10Be), short-lived environmental radionuclides (210Pb, 137Cs) and models of soil loss through water erosion (RUSLE) was used. This approach made it possible to compare natural areas (the Cerrado plateau in Brasília National Park) with land altered by human activities (a deforested plateau outside the park).
The results show how landscapes in geomorphological equilibrium (5-10 mm ka-1) can be disturbed by agricultural activities, leading to erosion rates at least 160 times higher. Although the estimates have a certain spatial limitation, they should help to shape effective conservation policies for the Brazilian Cerrado and raise the environmental awareness needed in response to the current crisis.
Soil erosion is a growing global threat, particularly in developing regions where human activities are significantly altering natural erosive processes. Through an innovative study in the Brasília region, this research demonstrates how agricultural activities are disrupting the geomorphological balance, causing erosion rates to increase 160-fold and jeopardising the sustainability of soil resources.
Lionel Siame
siame@cerege.frAix-Marseille University (CEREGE)