Análise multicrédito na determinação dos riscos à degradação ambiental da bacia hidrográfica do açude Cachoeira dos Alves - Itaporanga-PB.

Abstract

The preservation of the environment is subject to the sustainability of ecosystems, being essential factor to the quality of life of the populations. Natural resources such as soil, water and vegetation should be adequately exploited using conservation practices and under the principles of environmental sustainability while avoiding the degradation of the land. Inadequate practices of land use and occupation has provided the breakthrough and the intensification of environmental degradation in the world, and more severe in semi-arid regions characterizing the phenomenon of desertification of the land. In this context, the work had as its goal the determination of risks the environmental degradation of the river basin of the Waterfall weir of Alves, located in the municipalityof Itaporanga-PB with the use of the methodology of multicriteria analysis Combination Weighted Linear (CLP) based on the variables slope, vegetation cover, soil type, population density and proximity to roads. The criteria were normalized using functions or Fuzzy logic conglomeration to unify the scales of measurement before their aggregation by the application of CLP. We determined the relative importance or weight for each criterion using the method of the analytical procedure Hierarchical (AHP) through consultation to a group of eight experts. Has produced a solid base of georeferenced data concerning the area of study, which enabled the spatialisation of potential risks to the environmental degradation in four classes: very low to low, low to medium, medium to high and high to very high. The consolidation of data on the responses of experts determined the relative importance of each criterion and their ranking, being: plant cover (46.18 %), slope (26.64 %), soil type (16.57 %), population density (6.92 %) and proximity to roads (3.71 %). With respect to risks toenvironmental degradation, the studies showed that the river basin analysis has 1,453.56 ha of area bound by the class of medium to very high risk to environmental degradation, 5,479.17 ha in class low to medium, 2,389.48 ha in class medium to high and 1,203.70 ha in high class a very high, corresponding respectively to 13.11 %, 49.41 %, 21.55 % and 10.86 % of the total area. The areas with the greatest risk to environmental degradation, class high to very high, are always located close to any water source, have low slope, high population density and low vegetation cover. It is concluded from the results that the use of assessment methods multi-criteria associated with the techniques of geoprocessing, and appropriate to the mapping of the risks to environmental degradation, aiming at the management of natural resources and support in making decisions.