Avaliação hidrológica preliminar para subsidiar a construção de cenários sobre o futuro da ocupação humana na Bacia Hidrográfica do Ribeirão do Gama e do Córrego Cabeça de Veado - Distrito Federal

Abstract

The scarcity of natural resources is one of the most acute environmental problems. Its major cause lies in the mode of human occupation resultant from multiple uses of soil. In this context, one may observe a discrepancy between the occupational model and the environment. The present study focuses on the Ribeirão do Gama and Córrego Cabeça de Veado small catchment area, situated in Lago Paranoá Basin, central area of Federal District. That area includes: Park Way urban area, blocks 15, 16, 18, 20, 21 and 23; Rural Zone Vargem Bonita, Água Limpa Ecological and a Scientific Reserve (University of Brasília) Ecological Station of Instituto Brasileiro de Geografia e Estatística (IBGE) and Jardim Botânico Biological Reserve. In such a situation in which water resourses must be used in a sustainable way, this dissertation aims to propose different scenarios, such as exploratory extrapolative and exploratory alternative, and a normative or a desirable one. The method chosen has been based on an analysis of environmental changes by means of interpreting satellite images, rainfall data, and the variation of rainfall in the years 1994, 1998, 2001, and 2005. An analysis of the rainfall data reveals a clear relationship between water balance and rainfall variations. The initial interpretation points to the fact that the decrease of the rainfall peaks has been proportionally far higher than the decrease of the average annual precipitation rates in the years 1994, 1998, 2001, and 2005. Moreover, the former have also shown an alerting irregularity in terms of frequency and intensity. On the scope a of synthesis, the research shows that the human action devoided of sustainable planning has resulted in a degradation of environment in the small catchment area. Thus, we have opted for the use environmental informations, as a means of identifying exogenous elements which may influence physical processes in the study area. Considering the results of the research, it appears feasible to envisage ways of bringing closer the decision-maker’s aspirations in relation the future, rather than a representation of a desire or a hope (utopia) to create a normative or desirable scenario. Thus, certain recommended actions for the study small catchment area can be highlighted in order to improve the existing territorial planning and to reinforce a democratic and participative model of governance.