Dinâmica espaço-temporal da cobertura vegetal e fatores contribuintes à desertificação na Sub-bacia Hidrográfica do Açude Forquilha - CE

Abstract

The term desertification can be defined as the degradation of areas located in arid, semi-arid, and dry sub-humid regions, resulting from various factors such as climate fluctuations and human activities. The phenomenon of desertification encompasses various spheres of society, impacting not only the environment but also populations. In-depth understanding of this phenomenon allows for the proposal of environmentally sustainable measures and solutions aimed at improving the natural quality of the environment and the quality of life of the people living in it. The main objective of this research is to understand the relationship between environmental systems, the spatio-temporal evolution of vegetation cover, and the contributing factors to desertification in the Açude Forquilha watershed, located in the municipality of the same name, in the Sertão de Sobral planning region. To achieve this, methodologies for identifying environmental systems based on the mapping of various natural attributes (geology, geomorphology, water resources, climatological aspects, pedological aspects, and vegetation cover) are used to determine the main factors contributing to degradation processes. Additionally, the methodology for detecting changes in vegetation cover through the subtraction of NDVI images, initially proposed by Crósta (1992) and Moreira (2005), is employed. The applied method, in order to obtain the results, was based on three distinct yet correlated steps: literature review, cartographic survey, and geospatial analysis, and fieldwork to confirm the data obtained in the previous steps. Two field interventions were carried out, with the first expedition conducted in August 2021, aiming to provide a general reconnaissance of the lower course of the watershed, located along the banks of Riacho Oficina. The second expedition, conducted in December 2021, focused on the recognition and analysis of the geo-environmental attributes of the watershed. As part of the fieldwork, a botanical identification survey was conducted to assess the state of conservation of the environment, considering that vegetation acts as a protective mantle for natural resources, and its distribution, density, and health conditions are capable of defining this state of conservation. Based on the data obtained in the field, it was possible to conclude the geo-environmental characterization of the watershed, including the delineation of environmental systems, as well as the application of the methodology for analyzing changes in vegetation cover. Desertification is an environmental and social problem that requires urgent implementation of effective measures for conservation and sustainable management of vegetation cover. The study of vegetation cover variation, both globally and by environmental system, offers valuable insights to guide actions and policies aimed at mitigating and preventing desertification. These results contribute to the development of a database, facilitating monitoring actions, decision-making processes, land conservation, and other environmental services.