Análise integrada de dados físico-químicos das drenagens da porção nordeste do Lago Descoberto, na Bacia Hidrográfica do Descoberto

Abstract

This work consists in the analyzes integrated of physiochemical data of the drainages of the northeast portion of the Descoberto Lake, in the Descoberto Basin in Distrio Federal , including the tributaries Ribeirão Rodeador, Ribeirão das Pedras, Chapadão da Onça, Córrego Chapadinha, Córrego Rocinha and amount of north Descoberto river. The Work possesses analyzes of the evolution of the uses and occupations of the soil of the area where are located the tributaries in the northeast portion of the Descoberto Basin. That analyzes is done starting from multitemporais images of remote sensoriamento of the area. The images reflect the evolution of the use and occupation of the northeast of the Descoberto Lake from 1973 to 2003. The data for you analyze them physiochemical were given up by the Company of Sanitation of Distrito Federal (CAESB) and the images supplied by the Laboratory of Environmental Characterization of the Catholic University of Brasília. After the statistical treatment of the data of CAESB the obtained results were confronted with the legislation regarding the use of the water. In agreement with the results of the physiochemical analyses and of the permissible maximum values found in the effective legislation the quality of the waters of the tributaries, for the purpose of drinkable water supply they are satisfactory. The only of the parameters that presented values above allowed was it the conductivity. Satélite Landsat's images generated maps for the understanding of the evolution of the use and occupation of the soil of the area. Starting from the images it is possible to establish that the main changes happened in the area say respect to the occupation of the soil, to changes in the vegetation, the appearance and consolidation of the rural units and the territorial evolution of the city-satellites of Brazlândia and Ceilândia. The uses and occupations of the soil in the northeast portion of the Basin of the Descoberto are still predominantly destined to the agriculture activities, however in that area the appearance of the phenomenon of the horizontal condominiums is already observed. The territorial growth of the satellite cities of Brazlândia and Ceilândia is influencing the dynamics of the territorial occupation of the analyzed area. And the occupation of the northeast area of the basin of the Descoberto generated the progressive substitution of the original vegetation of the area for the planting of several cultures. In forty years of use and occupation of the area, the arboreal volume of the ciliary forests decreased considerably, as well as the volume of the original vegetation. The situation of the area and of the tributaries of the Descoberto Lake in the northeast area still presents a favorable situation, in what he/she tells respect the quality of the water of those ix drainages ones. The tributaries of the northeast area of the Basin of the Descoberto are not contributing indeed to the degradation of the quality of the water of the Descoberto Lake as well as for the sanding of the lake. This area can contribute for the aggravation of those problems through the change of the uses of occupations of the area, in the transformation of rural units in urban conglomerate.