The impact of the ongoing deforestation on the hydrological cycle: a case study of the Cuiabá-Santarém highway / O impacto do desmatamento no ciclo hidrológico: um estudo de caso para a rodovia Cuiabá-Santarém

AUTOR(ES)
DATA DE PUBLICAÇÃO

2005

RESUMO

This study aim was to evaluate some impacts on the hydrological cycle, specially the precipitation pattern, due to the regional deforestation along the corridor of the Cuiaba-Santarem highway (BR-163), using a high resolution (16x16 km grid) atmospheric model, the Regional Atmospheric Modeling System (RAMS), in its Brazilian version, the Brazilian RAMS or BRAMS. A deforestation scenario for 2026 has been provided by empirical models of deforestation, under no governance conditions (also known as the business-as-usual scenario) and it has been used in this study. The time length of simulation was 40 days, from October 10th to November 30th. The forcing data of 2002 were provided by the NCEP/NCAR Reanalysis Project. Mean rainfall decreased 7% in the region in which the forest was replaced by pasture. There were no substantial changes where the forest land cover was kept undisturbed. However, the rainfall showed spatial variability due to the local circulation (thermal) induced by land cover heterogeneity. Over the pasture area (deforestation), hot air rises by convergence carrying water vapor from the undisturbed forest located close to the pasture increasing the convective precipitation. This local cell is approximately twice as big as the deforestation length. In the BR-163 study case, the cell was located nearest to the west side of the land cover transition area (forest-pasture) where the rainfall rate increased. On the east side and over the deforestation area, the precipitation rate was reduced. The diurnal cycle of the precipitation has been slightly changed in the deforestation case. During the day, it was not possible to identify the rainfall maximum while at night it suggested a slightly increase of precipitation. The response of the fluxes and surface variables may be different depending on its topography level. A small rainfall reduction has been observed where the forest was kept undisturbed over 500 meters.

ASSUNTO(S)

deforestation amazônia rodovia desmatamento environmental impact atmospheric precipitation highway precipitação atmosférica biosfera hydrological cycle ciclo hidrológico amazônia impacto ambiental biosphere

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