Diagnóstico Físico Conservacionista de 10 Microbacias do Rio Capivara – Botucatu (SP), Visando O Uso Racional do Solo
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Data
2002
Autores
Araujo Junior, Armindo Alves [UNESP]
Campos, Sérgio [UNESP]
Barros, Zacarias Xavier de [UNESP]
Cardoso, Lincoln Gehring [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
A região onde está inserida a área de estudo, tem sofrido explorações predatórias e má utilização do solo. Áreas antes ocupadas por cerrados, campos sujo e limpo foram substituídas pelos reflorestamentos com eucalipto, devido aos incentivos fiscais e a instalação de companhias reflorestadoras na região, pelo baixo valor das terras e baixa fertilidade do solo; mas com um grande potencial para o desenvolvimento de essências florestais. O presente trabalho visou a elaboração do Diagnóstico Físico Conservacionista da bacia do rio Capivara - Botucatu (SP), baseada no parâmetro ambiental “Coeficiente de Rugosidade”, tendo-se por unidade de estudo 10 microbacias. Os resultados obtidos com a metodologia utilizada, no estudo da bacia do rio Capivara - Botucatu (SP), para o diagnóstico físico conservacionista permitiram mostrar que o grau de deterioração físico ambiental para a bacia foi 44,34%, muito acima do limite de 10% aceitável. O alto valor do grau de deterioração, provavelmente, foi devido ao mau uso da terra que vem provocando erosões, assoreamentos de reservatórios e cursos d’águas. O parâmetro ambiental médio “coeficiente de rugosidade” para as dez microbacias do rio Capivara, permitiu classificá-las para utilização com agricultura e urbanização, pecuária e reflorestamento; ou seja, indicou que a vocação principal desta é para uso com pecuária (Classe B); as classes de declive de 0 a 12% (Classe III) e de 12 a 20% (Classe IV), respectivamente, predominaram em 62,95% e 27,00% da área total das microbacias estudadas, ocorrendo em na sua maior parte nas unidades de solo LVA (46,56%) e RQ (19,86%). A predominância de florestas, capoeiras e pastagens nas microbacias, provavelmente é reflexo da predominância de solos de baixa fertilidade. - As imagens do Sensor TM do LANDSAT 5, permitiram o mapeamento do uso da terra da bacia de maneira rápida, que segundo o índice Kappa foi de boa qualidade (0,45), além de fornecer um banco de dados para futuros planejamentos nessa área. O SIG - IDRISI permitiu constatar através de seus diferentes módulos para georreferenciamento, classificação digital do uso da terra e modelo matemático, as áreas de uso da terra com rapidez. Os parâmetros, coeficientes de forma e circularidade mostraram que as microbacias apresentam baixo perigo de enchentes devido ao seu formato, bem como, o coeficiente de rugosidade permitiu classificar as microbacias 1, 2, 3, 4 e 8 com vocação para agricultura; as 6 e 7 para pecuária; a 5 para pecuária e reflorestamento e as 9 e 10 para floresta e reflorestamento.
The region where the study was focused has been under predatory exploitation and bad land usage. Areas that had been initially scrublands and clean and dirty fields are now being replaced by eucalyptus reforestation as a result of both tax incentives and low price lands (in that specific usage) but with a great potential for forest essence development. This study aimed to elaborate the physical conservation diagnosis of ten watersheds of Capivara River for rational soil occupation, based on the coefficient of roughness. The results and the methodology applied in the study showed that the level of environmental physical deterioration was 44.34% and it was much higher than the 10% acceptable limit. The high deterioration level was probably due to bad land usage which has been causing erosion, silting of water reservoir and creek sedimentation. The average environmental parameter coefficient of roughness for the watersheds of Capivara River allowed their classification for agricultural, cattle-raising and reforestation usage, i.e., mainly for cattle-raising usage ( B Class). The watershed largest part (62.95%) belongs to 0 to 12% slope class, in LVA (46.56%) and RQ (19.86%) soil units. The forest, savanna and grazing land predominance is probably a consequence of low fertility soil presence in the watershed (RQ and LVA). The 5 LANDSAT TM sensor images allowed land usage mapping quickly as well as provided database for future planning. The SIG-IDRISI allowed to verify through its different modules for georeference, digital classification of soil usage and mathematical model, the areas of land using quickly. The parameters, the form and circularity indexes showed that the watersheds are at risk of flood due to their format. The coefficient of roughness classified the 1, 2, 3, 4 and 8 watersheds for agricultural purposes; 6 and 7 for cattle-raising; 5 for cattle-raising and reforestation and 9 and 10 for forest and reforestation.
The region where the study was focused has been under predatory exploitation and bad land usage. Areas that had been initially scrublands and clean and dirty fields are now being replaced by eucalyptus reforestation as a result of both tax incentives and low price lands (in that specific usage) but with a great potential for forest essence development. This study aimed to elaborate the physical conservation diagnosis of ten watersheds of Capivara River for rational soil occupation, based on the coefficient of roughness. The results and the methodology applied in the study showed that the level of environmental physical deterioration was 44.34% and it was much higher than the 10% acceptable limit. The high deterioration level was probably due to bad land usage which has been causing erosion, silting of water reservoir and creek sedimentation. The average environmental parameter coefficient of roughness for the watersheds of Capivara River allowed their classification for agricultural, cattle-raising and reforestation usage, i.e., mainly for cattle-raising usage ( B Class). The watershed largest part (62.95%) belongs to 0 to 12% slope class, in LVA (46.56%) and RQ (19.86%) soil units. The forest, savanna and grazing land predominance is probably a consequence of low fertility soil presence in the watershed (RQ and LVA). The 5 LANDSAT TM sensor images allowed land usage mapping quickly as well as provided database for future planning. The SIG-IDRISI allowed to verify through its different modules for georeference, digital classification of soil usage and mathematical model, the areas of land using quickly. The parameters, the form and circularity indexes showed that the watersheds are at risk of flood due to their format. The coefficient of roughness classified the 1, 2, 3, 4 and 8 watersheds for agricultural purposes; 6 and 7 for cattle-raising; 5 for cattle-raising and reforestation and 9 and 10 for forest and reforestation.
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Irriga, v. 7, n. 2, 2002.