Influence of the land use and occupation in hidrologic availability of river basin Uruçuí-Preto, Piauí

Abstract

The aim’s was to verify the influence of changes in land use and occupation in water availability in the river basin Uruçuí-Preto, Brazil, in the period 1984 to 2007. For the assessment of land use were used images from satellite Landsat 5 TM sensor (Thematic Mapper) and the classification of imagens was made by automatic supervised classification with the maximum likelihood algorithm. For the analysis of the hydrological behavior were used average flow data, maximum and minimum annual, minimum flow with seven days of annual duration (Q7) and flow rates associated with stays of 90% (Q90) and 95% (Q95) of the year. For the association between flow and land use was made the simple correlation between the variables, testing its 5% significance (p < 0.05). The results showed that when comparing the years 1984 and 2007, the Cerrado and Mata Riparian classes decreased 20.9% and 2.4% respectively, Solo Exposed / Crop Field class increased 13.48% and Burned Areas class increased by 9.83%. There were no significant correlations between changes of class variables in the use and occupation of land and the flows, due to the large area of the basin that has consequently reduced the hydrological effects.