Dinâmica da cobertura e uso da terra na bacia hidrográfica do Ribeirão Água Fria, Palmas-TO: aspectos multitemporais à luz da legislação urbanística e ambiental

Abstract

The inadequate management of land use due to the urbanization process and agricultural activities put the quality of natural resources at risk, leaving hydrographic basins vulnerable to the degradation of their water resources. In Palmas, Tocantins, the Água Fria river watershed presents an intensive panorama of expansion of the urban perimeter since the initial territorial occupation front of the city to the present days Thus, territorial occupation interferes in the land cover and use dynamics, especially in protected areas of the basin. Therefore, the present study aimed to analyze changes in land cover and land use in the Água Fria river watershed, as well as to relate them to environmental and urban legislations within the time frame of the years 2008 and 2018. The methodology implemented consisted of literature review, analysis of the urban occupation of the city of Palmas, Tocantins; interpretation of urban and environmental legislation, GIS processing techniques and visual site analysis. The obtained results revealed that the supervised management of the APA Serra do Lajeado, in the middle course of the basin, refrained the expansion of land uses, such as the cultivation of annual crops, presenting a decrease of 0,42% in the class areas of grains and cereals. In addition, there was an increase of 3,65% in the pasture class and 3,46% in the shrubbery forest class area. The high course of the basin remains in a good state of conservation because it contains parts of the springs in the Lajeado State Park (PEL) and the escarpments of the Serra do Lajeado, which maintains the native vegetation protected, and it is represented by the class of forests in the years analyzed. In the lower course of the hydrographic basin, there was strong pressure from the growing of irregular urban areas as a result of high land prices in central urban areas with more infrastructure, which resulted in an increase of 0,89 km² of occupation in that area of the basin. Moreover, the new city Master Plan, Law nº 400, of April 2018 (PALMAS, 2018) approved the expansion of the urban perimeter in the basin, which may cause major environmental impacts, resulting in the degradation of the soil and the existing stream. The Permanent Preservation Areas (APPs) and the Urban Green Areas (AVUs), located in the lower course of the basin, showed occasional changes in the conflicting use of land, mainly represented by the classes of irregular land subdivision and dams; in addition to degradation of native vegetation of APPs for the installation of urban infrastructure during land regularization processes.