Morfometria e avaliação da vulnerabilidade hídrica obtidas por geoprocessamento e monitoramento espaço - temporal da qualidade da água na microbacia Ribeirão das Pedras – Quirinópolis/GO

Abstract

Environmental vulnerability analysis allows for the assessment of ecosystems under specific pressures. This information is useful for environmental planning as it helps identify areas where environmental damage may have a greater impact and to develop programs to reduce pollution sources. In this context, the present study aimed to map and analyze areas with different levels of risk to the environmental degradation process of the Ribeirão das Pedras Micro-Watershed, located in the municipality of Quirinópolis, in the Goiás. After a systematic review, it is divided into three chapters as described below: In the first chapter, the morphometric characteristics of the watershed were mapped, where the results indicate a watershed area of 261.6964 km2, with a perimeter of 88.9259 km, presenting an elongated shape and a regular density of 0.8206 km/km2. The drainage pattern is dendritic, with strong structural control in the northwest-southwest direction. The hydrographic density is low, with 0.098 channels/km2. Morphometric aspects indicate a low tendency for flooding, corroborated by the circularity index, compactness coefficient, and form factor. It highlights that morphometric data, with Geographic Information System (GIS) information such as location, area, and Digital Elevation Model (DEM), are crucial for the management of water resources of Ribeirão das Pedras, in Quirinópolis – GO. About 85.82% of the watershed area has a slope classified between Flat and Gently Undulating, favoring a smooth water runoff with moderate speeds. Factors such as the Gravelius index and the relief ratio index contribute to the maintenance and conservation of the area. In the second chapter, the objective of the study was to evaluate the quality and quantity of water in the Ribeirão das Pedras micro-watershed in Quirinópolis, considering the spatial scale during a hydrological cycle and its relationship with land use in sub-watersheds. Six collection points were evaluated for parameters such as pH, dissolved oxygen, temperature, turbidity, electrical conductivity, color, and oxidation-reduction potential, with collections every two months in the year 2023. Soil data, hypsometry, slope, and land use and cover were obtained and processed with QGIS v3.22. Land use classes were identified and quantified for each sub- watershed, related to water collection points. The correlation between land use and water quality parameters was analyzed using Pearson's correlation coefficient. Collection points 5 and 6 showed the highest significant values of electrical conductivity, dissolved oxygen, and pH, indicating probable influence of anthropogenic activities, with 81.3% of the total area of the micro-watershed being predominantly used for agriculture. In the third chapter, a multi-criteria analysis methodology was used with the support of geotechnologies, including remote sensing products, and GIS techniques, to evaluate the risk of environmental degradation in the micro-watershed. Various criteria were considered, such as land use and occupation, soil class, slope, housing, and weightings were carried out using techniques from the Analytic Hierarchy Process (AHP) method. The environmental fragility map is crucial for identifying degraded areas, and the results indicate that 69.56% of the Ribeirão das Pedras Micro-Watershed (17,946.04 hectares) show high acidity and low fertility, requiring correction. The region's relief favors erosion and inadequate drainage, while urbanization increases water pollution. The vulnerability of the areas, associated with intensive agricultural practices, highlights the urgent need to implement sustainable management to improve environmental resilience.