Crescimento urbano e impactos ambientais na cidade de Anápolis, Goiás : o caso da Região Noroeste

Abstract

It is common in the stage under which the Brazilian cities find the existence of an altered physical environment provided with serious environmental impacts and difficult to control. These impacts are mostly manifested as silting, landslides, flooding, retraction and contamination of the water table, erosion, soil subsidence, etc. The formations of these problems stem mainly from accelerated urbanization without planning where the natural characteristics of the physical environment are disregarded. The development of the city of Anápolis oriented by an economic perspective made its area attractive, inducing a growing urbanization. The research in question addresses the environmental impacts of accelerated growth in the northwest of the city. Based on theoretical review and data collection in the field, thematic maps (Geology, Geomorphology, Pedology, Hypsometry and Declivity) were elaborated aiming at the knowledge of the characteristics of the physical environment on which the urban area was constituted. Related to soil types and slope gradients allowed the elaboration of the vulnerability map, which pointed to the areas most subject to the installation of environmental impacts. According to the map of vulnerability, these locations are concentrated in the northwest region, where the dissecting modeling is located, considered to be the most critical of the studied area. With respect to the geological structure, most of the city is located on the Granulítico Anápolis-Itauçu complex, composed by ortogranulitos and paragranulitos. Also identified in the domains of the city were the Detrito-Lateritic roofs and the alluvial deposits. The area is formed in a small part of the Alto Tocantins Paranaíba Plateau, characterized by a variety of relief forms, with altitudes located in the interval between 900 and 1100m. These units are divided into two groups: Regional Surface of Plantation, with altitudes varying between 900 and 1000m, with strong dissection (located at the ends of the Northwest and West regions of the city) and Regional Surface of Planar with altimetric dimensions in the order of 900 and 1000m and medium dissection (predominant in the area of the city). According to Lacerda (2004), lower altitudes, more drainage and steeper slopes are also to the west, with lower altitudes, lower channels and lower slopes, located in the eastern part. Three types of modeling were identified: flattening (tabular forms and 1st and 2nd generation ramps with low slopes); dissection (low slopes, hills and ridges, with high slopes) and accumulation (fluvial plains and terraces). Among them, the most vulnerable is the dissection located on the Northwest, West and Southwest edges. Regarding the soils, two basic types were identified: Latosols (Red and Red - Yellow), predominant, and Argisols. Land use in these places is intense and mostly residential. This type of occupation does not match the capacity of the physical environment in question, given the existing natural vulnerability, which contributed to the formation of important environmental impacts.