Eliomar Pereira da Silva Filho

Patterns and impacts of deforestation in Rondônia, Brazil

Abstract Land development in the Brazilian Amazon has gone through phases of rubber extraction, agricultural development, immigration, road expansion, and promotion of large enterprises in cattle ranching, timber extraction and mining. Land development patterns in the western state of Rondonia provide a place to focus on rapid development and its effects. The expanding land-use activities in Rondonia have resulted in an increase in the human population and the rate of deforestation so that by 1993 about 25% of the forest area had been cleared. In Rondonia the main activities responsible for the deforestation are small farmers, cattle ranchers, miners and loggers. The implications of the Rondonia Natural Resource Management Project (PLANAFLORO), which is just now being implemented, are critical to the future of the environment and economy of the region.

Influência do Uso e Ocupação do Solo no Escoamento Superficial na Cidade de Ji-Paraná-RO, Amazônia Ocidental (Influence of Land Use and Occupation in Runoff in the City of Ji-Paraná-RO, Western Amazon)

No municipio de Ji-Parana/RO, a ocupacao urbana ocorreu de forma desordenada as margens dos rios Urupa e Machado, tornando parte da area urbana suscetivel a inundacoes. O presente estudo teve como objetivo a caracterizacao do uso recente do solo em seis bacias hidrograficas que integram o perimetro urbano de Ji-Parana, a partir da utilizacao do processamento digital de imagens (PDI), sendo verificado que todas elas possuem mais de 20% de sua area impermeabilizada. Tambem foi verificada a influencia da urbanizacao das bacias no escoamento superficial, com base nos dados provenientes da analise de chuvas intensas, sendo mensurado o tempo de concentracao (tc) pelo metodo de George Ribeiro, Kirpich e Kirpich Modificado; o coeficiente de escoamento superficial (C) pelos metodos de Horner e Fantoli; e as vazoes maximas de projeto (Q) pelo metodo racional; cujos resultados nao diferiram estatisticamente. A B S T R A C T Urban occupation in the city of Ji-Parana/RO occurred on the banks of Urupa river and Machado river in a disorderly manner, making part of the urban area susceptible to floods. This study aimed to characterize the current land use in six watersheds that comprise the urban perimeter of Ji-Parana using the digital image processing (DIP). It was found that all of them have more than 20% of its area impermeable. The influence of urbanization of watersheds in the runoff was observed based on data from the analysis of heavy rainfalls, and the time of concentration (tc) was measured by the method of George Ribeiro, Kirpich and Kirpich Modified; the runoff coefficient (C) by the methods of Horner and Fantoli; and the project peak flows (Q) by the rational method; the results were not statistically different. Keywords: Watershed, Digital Image Processing, Heavy rainfall, Concentration Time, Peak Flow.