Denilson Dortzbach,Iria Sartor Araujo,Ivan Luiz Zilli Bacic,Raphael Ribeiro Souza, Epagri, Ciram, agrofloripa@yahoo.com.br
ABSTRACT
This paper aims to show the changes that occurred in the drainage network of the Ribeirão Gustavo watershed and tributaries, located in the municipality of Massaranduba, SC. The changes were verified through analysis of the morphometric variables by means of different sources to obtain the drainage network: a) through the interpretation of aerial photographs at 1:25,000 scale and field check using navigation and topographic GPS; b) use of the IBGE cartographic database (1980) at 1:50,000 scale, c) automatic extraction of the SRTM drainage network using MDT. For morphometric analysis, the quantification of parameters was prioritized: drainage area, perimeter, drainage density, watershed shape, sinuosity, concentration time and order of the watershed watercourses. The drainage system was considered as an adequate indicator of environmental changes occurring in the study area, especially in the analysis performed with aerial photo interpretation. The results showed dramatic changes in the drainage network resulting in changes in the landscape and in the elements that compose the watershed, with changes in mouth and bounds. Morphometric analysis indicated differences between parameters evaluated using the different data sources. The downstream areas at the valley bottom were those that showed the greatest differences. The results allowed concluding that the watershed has undergone changes in its drainage network and morphometric characteristics, comparing the different data sources evaluated, as a result of the increased human activity, especially related to irrigated rice cultivation.
Keys-words: agriculture, morphometric analysis, watershed