Mapeamento das áreas de preservação permanente do município de porto alegre para análise da qualidade de produtos cartográficos

As Áreas de Preservação Permanente (APPs) foram criadas devido à sua grande importância para preservar o meio ambiente e sua ocupação inadequada trouxe impactos negativos para o bem-estar e segurança do homem. O novo Código Florestal Brasileiro de 2012 modificou os parâmetros para a delimitação dessas áreas, resultando em uma nova demanda de atualização e mapeamento preciso dos novos limites. Como a maior parte do território brasileiro não está coberto por produtos cartográficos compatíveis com o que é estabelecido pela legislação, recentes pesquisas apontam para uma redução quase total de algumas classes das APPs, em especifico as de topo de morro. Então, neste trabalho foram usados os produtos cartográficos gerados pelo mapeamento do município de Porto Alegre, considerado hoje como um dos mais modernos e completos do Brasil, para delimitar as APPs e avaliar os resultados. A área de estudo utilizada foi o município de Porto Alegre excluindo-se as ilhas que compõe seu território, resultando numa área de 451,5 Km2. Para gerar as APPs de topo de morro foi usado o método de Oliveira et. al. (2013) com uma modificação no cálculo da declividade média e um MDE gerado com dados de LIDAR. E para gerar as APPs de hidrografia foram usados produtos cartográficos na escala 1:1.000. Considerando-se o Guaíba um lago foram delimitados 89,4 Km2 de APP de hidrografia, mas considerando-se o Guaíba um rio só 65,5 Km2 foram considerados APP de hidrografia. As APPs de topo de morro resultaram numa área de 9,5 Km2. E não foram encontradas APPs de declividade Due to using all the pixels of the hill for the calculation of the average slope it ended up excluding almost all the hills because they did not reach a value of mean slope sufficient for that their upper third were considered APP, this happened because the area around the hills is very inclined but the top of the hills are very flat and wide, therefore were concluded that this is not a good method of calculation. With regard to APPs of hydrography the scale of the cartographic products interfere in the delimitation and size of them; it was verified that rivers with distances between margins of more than 10 or 50 meters are usually represented only by a single line, thus, not being able to determine a true range of APP around the rivers. Furthermore, because of the cartographic generalization, many smaller rivers do not appear in cartographic products and they should have APP along the margins, this causes large loss of the real size of APP. Many rivers represented in the cartographic basis in the 1: 1,000 scale of Porto Alegre, both perennial and intermittent, are not represented on scales as from 1: 10,000 or 1: 25,000 of other data sources because they are considered of minor importance.Permanent Preservation Areas (PPAs) were created due to their great importance to preserve the environment and their inadequate occupation brought negative impacts to the well-being and safety of man. The new Brazilian Forest Code of 2012 modified the parameters for delimitation of these areas, resulting in a new demand of updating and precise mapping of new limits. As the most part of the Brazilian territory is not covered by cartographic products compatible with what is established for the legislation, recent researches point to a almost total reduction of some classes of the PPAs, in specific the top of hill. So, in this work were used the cartographic products generated by the mapping of the city of Porto Alegre, considered today as one of the most modern and complete in Brazil, to delimit the APPs and evaluate the results. The area of study used were the city of Porto Alegre excluding the islands that composes its territory, resulting in an area of 451.5 km2. To generate the APPs of top of hill were used the method of Oliveira et al. (2013) with a modification in the calculation of the average slope and a MDE generated with LIDAR data. And to produce the APPs of hydrography were used cartographic products in the 1:1,000 scale. Considering the Guaíba a lake were delimited 89.4 Km2 of APP of hydrography, but considering the Guaíba a river only 65.5 Km2 were considered APP of hydrography. The APPs of top of hill resulted in an area of 9.5 km2. And were not found APPs of declivit