The present work had aim as classify, map and quantify, in recognizing levei, lhe use of land in the Cadena County and Passo das Tropas sub-watershed -of Santa Maria - RS. Pancromathic aerophotograms obtained in 1964 and 1975, with 1:60.000 and 1:110.000 scale approximately, respectively, and color composites from the TM-LANDSAT 5 of 1986 and 1987, in the 1:100.000 scale approximately were used. In the quantification of the areas were used the sistematic sampling technique by dot grid. According to the obtained results, it was observed the Class Pasture predominated upon the others in the three studied epochs and ocupping 65,2% of the area in 1964, 68,1% in 1975 and 67,4% in 1986/87. The Class Forest presented a decrease in 30,8% and the Class Agriculture in 17,6% in the period from 1964 to 1986/87; in this same period the Class Constructions increased its occupation in 64,6%. The sistematic sampling technique by dot grid was applied in the quantification of the areas and overestimated the area of the subclass drainage network in 354,0% and the subclass higway system in 287,6% (average of the three survey epochs).
land use; temporal valuation; sub-watershed
