Cartographic and aerophotogrametric techniques in the study of erosion: high basin of the river Araquá, municipality of Sao Pedro and Charqueada / SP / Técnicas cartográficas e aerotogramétricas no estudo da erosão: alta bacia do Ribeirão Araguá - São Pedro e Charqueada / SP

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

This study aimed to make an inventory of the forms of linear erosion in the high basin of the river Araquá, municipality of San Pedro and Charqueada / SP, based on cartographic and aerophotogrametric techniques in analog and digital environment. The survey was conducted in 2 different scales of approach: 1:50.000 (semi-detailed) and 1:15.000 (detailed). In the semi-detailed scale, it was produced a hypsometric chart, a slope chart and a morphological map, where the forms of linear erosion were represented. These products, with the informations about soils, lithology and land use, led to the morphopedologic map. Based on this map, was choose the sub-basin of the Querosene stream for the study on detailed scale. In the sub-basin of the Querosene stream were produced hypsometric and slope charts, morphologic, soils, land use and linear erosion maps. The survey of land use and linear erosion was based on photographs of 4 different periods, 1962 (1:25.000), 1978 (1:35.000), 1995 (1:25.000) and 2006 (1:30.000). This diagnosis made possible to create a susceptibility erosion chart and to correlate forms of linear erosion with the characteristics of the physical environment as well as assessments of the temporal evolution of the erosion. The results showed that the area affected by furrows decreased 38,18% from 1962 until 2009. In contrast, the areas with grazing tracks made by cows increased 137%. In the same period, the number of ravines increased 87,5% and gullies about 300%. The data also showed that the ravines and gullies are preferably in hollow forms, >10% slopes, mainly in areas of very sandy, deep, homogeneous and permeable soils, which are covered by grassland or ciliary vegetation. The techniques of digital aerophotogrametric interpretation and restitution showed far superior to analog, but the digital process is slowest than the analog. The digital techniques allowed the correction of most of the geometric distortions of the photos, facilitating, thus, the measures of ravines and gullies.

ASSUNTO(S)

fotointerpretação erosão photogrametry photointerpretation fotogrametria mapeamento geomorfológico erosion geomorphological mapping

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