Multitemporal Analysis of Forest Cover in the Arroio Grande Small Hydrological Basin, Santa Maria, RS

Abstract

This work aims to carry out a multitemporal analysis of the forest cover of Arroio Grande small hydrological basin located in Santa Maria, RS, Brazil. Four satellite images were used: LANDSAT 5 (1987), LANDSAT 5 (1995), LANDSAT 7 (2002) and CBERS 2 (2005). The images were classified according to the Bhattacharya algorithm. After the classification of such images, the crossing of the thematic maps was accomplished. Maps with different land uses were obtained: unaffected forest cover, regeneration and deforestation for the period 1987 - 2005. During 18 years, the forest cover increased 10,24% in the basin area, changing from 14.135,42 ha (40,01%) in 1987 to 17.752,20 ha (50,25%) in 2005. This happened because the State Forest Law has become effective as well as the rural owners´ consciousness and also due to increment of exotic forest plantations in the State.