Human modification of stream valleys in the western plateau of São Paulo, Brazil: implications for environmental narratives and management

Deforestation, agricultural land uses and urbanization have altered stream channels and floodplains in many regions of the world, yet occurrences of post-settlement alluvium (PSA) and benchmark pre-settlement horizons (Palaeosols) are unreported in many tropical and subtropical developing countries. Twentieth century land uses, motivated strongly by state subsidies in the cases of coffee and cotton cultivation and soy – wheat double cropping, caused soil erosion and the corresponding formation of PSA and stream-channel changes in small catchments of the Western Plateau of Sao Paulo State, Brazil. Analysis of land-use changes suggests necessary alteration of regional environmental management for restoration planning, water quality monitoring and control of gully erosion. Narratives of regional environmental change should address the impacts of agropastoral land uses on soil and water resources, rather than concentrating on deforestation and forest land cover. Copyright © 2000 John Wiley & Sons, Ltd.