Sediment morphology and distribution in a reforested riparian zone / Caracterização e distribuição espacial dos sedimentos depositados numa zona ripária reflorestada

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

Agricultural pratices in the state of São Paulo - Brazil, are directly responsible for the suppression of the natural vegetation cover and soil degradation. The natural vegetation was substituted by coffee, pastures, citrus and sugar-cane crops, over centuries of occupation and land use. The native forest recuperation prevents soil erosion and reduces environmental impacts. Riparian forest traps sediments transported by "splash" and runoff. Sediments deposition in riparian zone depends on rainfall, geomorphology, original soil characteristics and management. Sediment distribution paths in riparian zones reflect the deposition dynamics and the type of deposition event. In order to study the deposition processes in a riparian forest located in the county of Iracemapolis-state of São Paulo, macro and micromorphological analyses, as well as particle size distribution using Folk &Ward (1957) parameters, were done. Soil samples were dispersed with sodium hexametaphosphate and water. This last technique was done to simulate field transport conditions. The particle size distribution results together with the field and laboratory morphological analyses showed an irregular and non-uniform sediment deposition. This deposition process suggests the occurrence of high intensity erosive events that produce high amount of sediments and runoff characterized by a turbulent flow. Land use changes significantly affect this type of deposition. The recuperation of the natural forest dislocated sediment deposition inside the riparian forest 25 m upslope.

ASSUNTO(S)

distribuição espacial sedimento erosion erosão sediments particle size distribution degradação do solo riparian forest image analysis mata ciliar

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