Áreas de preservação permanente e áreas de inundação: estudo de caso na área urbana de Itaqui, RS, Brasil

Abstract

The expansion of urban areas is associated with scientific and technological growth, since such resources have the potential to facilitate the survival of man in the most challenging environments. For the preservation of forests in Brazil, the instrument of governing law is the most representative New Forest Code. The present work has the main objective to delimit the Permanent Preservation Areas located on the banks of the Uruguay River and estimate the average area coverage of flooding coincident with the urban area of Itaqui RS. Still defined themselves the following specific objectives: a) to represent the flooded area of the city, b) to represent the limits of Permanent Preservation Area to the Uruguai River, the stream Cambai and sanga das Olarias in urban Itaqui. The study area was the urban area of Itaqui and waterways that surround it. Were used rainfall data from 1973 to 2013, measured by the weather station of Agência Nacional de Águas to the study of floods. The data were compared with the levels of flooding on the corresponding dates. In the study of Permanent Preservation Areas was held "buffering" corresponding to the water courses was conducted, according to the definitions of the New Forest Code. Was adopted for both steps using a Google Earth image coming and vector representation, held in Spring 4.3.3 Software, flooded in the 1983 flood, the areas of risk described by the Master Plan and the Defesa Civil de Itaqui areas, and the delimitation of Permanent Preservation Areas. It was found that five consecutive days had dimensions of increasing rain flood. It was also found that successive and sporadic rainfall has greater potential for causing flooding, as in 1983, when the largest share of the flood period studied occurred. Consulted, representations concerning the area flooded for the year 1983 proved to be compliant. The same can be observed when comparing the representations of the areas of risk described in the Master Plan Itaqui and the Defesa Civil. Permanent Preservation Areas were identified for 50 meters Sanga das Olarias , 200 meters and 500 meters to the Uruguay River and 100 meters for Cambaí , and the city has inhabited areas in the space provided the same .The incidence of five days of consecutive rain reflected in an increase in the records of assessments and subsequent days there is still the same increase, due to the volume of water coming from the river's headwaters . Of large flood events, what stood out was what happened in 1983 , reaching a mark of 14,51 m above the normal level of the Uruguay River . It is noteworthy, however, that the areas of risk disregarded by the Master Plan, although the area of recurrence, may pose risks because they are being neglected.