Avaliação do processo de desertificação nos municípios de Ouro Branco e Senador Rui Palmeira, no semiárido alagoano, a partir de sensoriamento remoto

Abstract

Most of the problems related to environmental degradation in the semiarid region stem from the region's own characteristics and the wrong way in which the land is used, disrespecting its favorable limits for biomass production, and thus making it vulnerable. Therefore, it is very important to carry out a verification of the semi-arid biome of Alagoas, in the municipalities Ouro Branco - AL and Senador Rui Palmeira - AL, to get a sense of the magnitude of the Caatinga degradation, due to the influences of the characteristics of the environment as well as of anthropic actions. In this work, remote sensing techniques were used for the identification, evaluation and classification of degraded areas susceptible to desertification in the analyzed municipalities. This study aimed to identify areas susceptible to desertification in the municipalities of Ouro Branco - AL and Senador Rui Palmeira - AL, from 2007 to 2020, in order to assess and classify the levels of degradation through remote sensing. In the methodology, precipitation, vegetation indices, soil moisture and land use and cover were used. The products of precipitation, vegetation and soil moisture were used as interannual averages, generated through monthly averages. As for the land use and land cover product, the reference data for the year 2018 was used. Each product was used in one or more stages to identify, assess and classify degraded areas susceptible to desertification in the analyzed municipalities. The results obtained during the study show that the regions with degraded areas have vegetation index values ranging between 0.0 and 0.4 and average annual precipitation values between 30 mm and 40 mm. It was also possible to notice that the response of the soil moisture product can have different behaviors according to the precipitation regime or the soil characteristics. The product of land use and land cover, from its own classification, made it possible to see that the soils of the studied region underwent changes in their soil types, where the main changes observed were: from natural vegetation to cultivated soil or agricultural soil. However, I conclude that the methodology adopted in the work was valid, because through the method used, it was possible to identify, evaluate and classify the areas, with different levels of degradation (very weak, weak, moderate, strong and very strong). After the classification of the areas, the data obtained were expressed in percentage. And among the classifications proposed in the objectives, no region was found that met the very weak degradation class, with a value of 0.0%. He also noted that the very strong degradation class stands out only in the region of the municipality Senador Rui Palmeira, with a percentage of 11.1% and 5.6% of the total area of analysis and the other classes were met in both counties.