A degradação da cobertura vegetal e a erosão dos solos como indicadores de áreas desertificadas: uma análise da microbacia hidrográfica do riacho Mucutú/PB

• Autor(a) principal: Pereira, José Antônio Vilar
• Data de Publicação: 2021
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UFPB
• Texto Completo: https://repositorio.ufpb.br/jspui/handle/123456789/23454
• topic: Microbacia do riacho Mucutú; Potencial natural à erosão; Erosão laminar; Degradação; Desertificação; Mucutú stream watershed; Natural potential for erosion; Sheet erosion; Degradation; Desertification; CNPQ::CIENCIAS EXATAS E DA TERRA::GEOCIENCIAS

The removal of vegetation cover is one of the main causes of the erosive processes that causes the elimination of the surface layer of soils, responsible for housing the humus and nutrients necessary for the development of plants. In view of this, erosion can cause the reduction or elimination of soil fertility. In the semiarid region this process is one of the main agents responsible for the emergence of deserted areas. In this scenario, this research has as its general objective, to perform a prognostic analysis of the areas at risk to the desertification process in the watershed of Mucutú/PB stream from the correlation of the degradation of the vegetation cover and its natural potential to erosion. The watershed comprises an area of 724,628 km² and is located between the geographic microregions of Seridó and Cariri paraibano, partially covering the area of seven municipalities. For the spatiotemporal monitoring of land use and cover, two Landsat 5 satellite images from 1990 and 2005 and an image of Landsat 8 from 2019 were digitally processed. The quantification of Natural Erosion Potential (NEP) was obtained through the analysis of the physical variables of the Universal Equation of Soil Losses (USLE): soil erodibility (factor K), rainfall erosivity (factor R) and the topographic factor (factor LS) from the algebra of maps. For the identification and spatialization of desertification risks, the multicriteria analysis technique was used, crossing the degradation maps of the vegetation cover and the variables of the NEP. The results indicated that the economic practices developed in the analyzed space-time resulted in the simplification and reduction of the density of the vegetation cover of the watershed, especially extensive livestock, subsistence agriculture and mining as the most degrading. A great variation in the natural potential for erosion was identified with values between 4,34 and 3.863 t.ha.year and an average of 62,32 t.ha.year. The lowest values are distributed in the flat areas, while the highest indices were verified in the areas of strong wavy relief where the Red Argisols and Regosols with high erodibility predominate. It was found that more than 81% of the territory of the watershed has High and Very High Risk to desertification, while only 3,4% and 14,34% present Low and Moderate Risk, respectively. The areas of greatest risk are located where there was greater degradation of vegetation cover, with soils of high erodibility and in the regions where agricultural and mining activities develop with greater intensity. On the other hand, the areas mapped as less at risk are located in the most difficult to reach regions, such as the top of the highlands that still have relatively conserved vegetation.