Carta de unidades geoambientais do município de Itanhaém, São Paulo, Brasil

Abstract

Coastal areas, due to morphological characteristics, are potentially susceptible to environmental changes, especially those related to the growing process of territorial occupation resulting from urbanization. In Brazil historically the coast has a very important role in territorial shaping. The first settlements from Europe, strategically positioned along the coast, allowed occupation and domination of space, and were the sites of communication between the New and Old World. As time passed, such places underpinned the national construction, serving as continental input and output gateways. In a few decades the rapid growth and development of coastal cities boosted physical and environmental conflicts. From the 1950s on, in the state of São Paulo, Brazil, with the popularization of automobiles and the consolidation of the main routes of communication between the coast and the uplands of São Paulo - Anchieta Highway (1953), Immigrants’ Highway (1976) and the second lane of Immigrants’ Highway (2002) - there was an increase in the population flow, especially to Baixada Santista (an official metropolitan area on the coast of the São Paulo state originally centered around the port city of Santos). A consequent and considerable increase in the floating population was verified, mainly consisting of tourists and second home owners. Currently the Baixada Santista Metropolitan Region is booming economically. In continuous transformations the Coastal Zone has undergone numerous operating procedures, including those related to the increasing industrialization in Baixada Santista, the development of the Cubatão industrial complex, the expansion of the Port of Santos, the investments of Petrobras and the tourism. Second homes, also known as vacation or seasonal home, cause a new impact on coastal areas by encouraging urban sprawl and disrupting the social fabric of coastal cities, often causing conflicts between the local and floating population. Another case that stands out is the increased migrant flow, attracted by the prospects of economic growth. Due to the lack of labor qualification, much of this flow is often not absorbed and people become marginalized. As a result of this process areas unsuitable for occupation are taken, favoring slums. In this context, this study was aimed at developing the Map of Geoenvironmental Units of the coastal city of Itanhaém, Baixada Santista, São Paulo, Brazil. Initially the study developed an inventory of physical attributes related to morphometry and of socioeconomic data, such as information from municipal and land use. Therefore data were integrated for the definition of geoenvironmental units according to the adaptation of the proposed methodology, based on the systemic approach by Mateo Rodriguez (2004). Thus for the drafting of the Map of Geoenvironmental Units mappings were conducted, which allowed the environmental characterization of the city and provided the identification of capabilities and weaknesses of the units set. Furthermore the information collected and generated was aimed to promote an increased knowledge of this coastal area. Thus the mapping done for the city allowed the identification of areas of greatest susceptibility to environmental problems, and is an important subsidy for understanding the environmental dynamics in addition to being a tool for the planning of coastal areas.The city of Itanhaém (SP) has a remarkable topographic subdivision. Based on the morphometric analysis two key environmental systems were identified for the city of Itanhaém: the mountain range system, which covers the Atlantic Plateau, the escarpments of the Serra do Mar and isolated hills, and the coastal plain system. As these systems were defined, the functional categories were determined, corresponding to emitting units, transmitting units and units collecting the matter and energy present in the city. The geoenvironmental subunits were delimited drawing on these categories, and their individualization considered the peculiarities in relation to physical conditions, such as morphometrics and geomorphology, and socioeconomic conditions, such as the presence or absence of urbanization and type of use associated. As a result twelve geoenvironmental subunits were determined within the group of functional units: 1. Plateaus - left bank of Mambu river; 2. Plateaus - right bank of Mambu river; 3. Plateaus - tributaries of the Black and White rivers; 4. Escarpments of Serra do Mar; 5. Isolated hills; 6. Marine terraces - level I; 7. Marine terraces - level II; 8. Urbanized marine terraces; 9. Slope deposits; 10; Fluvial plains; 11. Fluvial-marine plains; and 12. Marine Plains. The drafting of the Charter of Geoenvironmental Units allowed determining the relationship between usability, i.e. the physical characteristics of each geoenvironmental unit, and socioeconomic function related to land use in the city of Itanhaém. The analysis of the Map enabled to find the areas with conflict between geoenvironmental functions and human interventions. Many situations were found incompatible, confirming that human action in the environment is not limited by physical attributes, given the imposition of activities on dynamically fragile areas.