Resumo

DELAMARE, Tatiane Oliveira; SIMON, Adriano Luís Heck  e  SATO, Simone Emiko. Land use and lacustrine shoreline changes: the case of a Fishing Village in Pelotas, RS, Brazil. RGCI [online]. 2015, vol.15, n.2, pp.237-248. ISSN 1646-8872.  https://doi.org/10.5894/rgci543.

The formation of these lagoon bodies started in the Tertiary period, with the first cycles of sea advances and retreats resulting from glaciations, which rework on the sediments of the continental shelf leading to the formation of sandy barriers which isolated the flooded continental area, forming a new coastline with the predominance of fluvio-lacustrine morphodynamics. The lagoon coastal zones, as well as the sea ones, are submitted to an intense process of spatial occupation and the environmental changes complied to land use dynamics need to be understood and monitored to subsidize plans of coastal management. Taking this into consideration, this work was developed with the purpose of analyzing the changes in lacustrine shoreline of Z3 Fishing Village Z3 - City of Pelotas, Rio Grande do Sul State, Brazil, deriving from land use/cover dynamics during a period of 57 years, between the years of 1953 and 2010. The concept of land cover and land use adopted in this research is based on the definitions used by IBGE (2006; 2013b) which defines land cover as the elements of the nature: vegetation, water, ice, bare rocks, sand and similar surfaces, while land use is related to the group of social-economic activities. For the implementation of the work, land use/cover and morphohydrographic maps were elaborated for the scenarios of 1953 and 2010 and a comparative map of the lacustrine shoreline, starting from the data of the two scenarios was developed. The cartographic documents of the scenario of 1953 were organized based on the interpretation of tridimensional digital anagliphs obtained from panchromatic aerial photographs with approximate scale of 1:40.000. The 2010 scenario maps were elaborated based on the screen interpretation of a satellite image from the sensor AVNIR-2 (ALOS system) with 10 meters of spatial resolution. The geo-referencing, interpretation and vectorization of the angliphs information and the satellite image were carried out in the software ArcGis 10.0 environment, where the lacustrine shoreline comparative map was also elaborated, from the overlapping of the lagoon coastlines in the two analyzed periods. Finally, field works were carried out in order to enable the understanding of the changes found in the mappings. The lacustrine environment where the Z3 Fishing Village is located presents peculiar characteristics resulting from a process of spatial occupation, among which stand out the straightness of the watercourses, the grounding of lagoon segments for the construction of roads and lots for housing, besides the implementation of small ports for fishing boats. These interventions changed the Z3 Village shoreline characteristics significantly, modifying its morphodynamics. The data obtained through land use/cover maps from 1953 and 2010 corroborated for the understanding of such changes in the coastline, highlighting as positive the maintenance of forest areas which act as barrier to contain erosion in coastal environments as well as it keeps the pedogenetic characteristics. Another highlight is the growth or the urban area which occurred in an unbalanced way on the components of the physical-environmental system. The changes that took place in the hydrography of the Fishing Village were also intense, as the straightness and the grounding of drainage canals changed the characteristics of water drain in the area, increasing the the swamp areas, which ended overlapping other land covers thus changing the area vegetal composition. From the analysis and interpretation of the results, it can be concluded that the changes which occurred in the Patos Lagoon segment, where the Z3 Village is located, were intense and directly related to the process of urbanization and the fishing economic activity. As most sea or lagoon coastal environments, there was no adequate planning for the spatial occupation in the Z3 Village. Such situation is in disagreement with the Brazilian Federal Constitution which establishes that the Coastal Zone is a national heritage and its usage should occur according to the Law, under the conditions which assure the preservation of the environment including the usage of natural resources.

Palavras-chave : Lacustrine coastal zones; Spatial occupation; Environmental changes.

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