Avaliação ambiental das áreas de preservação permanentes das nascentes no município de Ronda Alta/RS pelo uso das geotecnologias

Abstract

Water sources (springs) are components of the hydrological system and promote the exfiltration of groundwater to the surface. As they are considered complex systems, they require special care to ensure their maintenance and sustainable use. Just like the water sources, their surroundings also deserve special attention, so much so that from the year 1965 onwards the Brazilian Forest Code established a protection area in their surroundings, with a radius of 50 meters that received the name Permanent Preservation Area. However, it can be seen that theory is far from practice. The present work aims to evaluate the characteristics of use in permanent preservation areas of water sources in the municipality of Ronda Alta/RS, using geotechnology tools. Initially, concepts related to geotechnologies were discussed in the areas of Remote Sensing, Geographic Information Systems and Satellite Positioning and some applications related to environmental themes.Topics related to the environment were also covered, such as water sources, their concepts and the impacts they have suffered, Brazilian Environmental Legislation and its evolution over the years, in addition to riparian forests, their importance, and the main environmental impacts they have suffered. To understand the dynamics of land use over the years, time series from MapBiomas collection 7 from the years 1985, 1990, 2000, 2010 and 2020 were used, combined by similarities in use and overlapped to identify changes. At this stage, the continuous growth of the urban area in all series is worth highlighting, in addition to the drop in the area of the rural vegetation class in the 2010-2020 decade and a significant increase in the agricultural class in the same decade, as well as an increase in the forest formation class. Regarding land use in the environmental preservation areas of the springs, geoprocessing techniques were used to obtain watercourses, the location of water sources, drone flights in some parts of the municipality for on-site assessment, and cutting out areas of permanent preservation on the land use map for the year 2022. 1,628 water sources were identified, of which only 557 had some type of vegetation within the preservation area, 27 with preservation above 75%, representing 1.66% of the total, and only 12 with 100% preservation, 0.74% of the total water sources. It can be highlighted that the use found in the vast majority of these areas is in the agricultural class, where activities related to it are being employed, and natural vegetation has been suppressed. Due to the expansion of human activities, water sources are being removed from the landscape through drainage processes or even canalization. It is worth highlighting their important role in the environment, for fauna and flora, water supply, formation of streams, and the need for actions to raise awareness and promote their preservation.