Avaliação do uso e ocupação do solo na microbacia do açude de General Sampaio através do sensoriamento remoto

Abstract

Land use and occupation is a direct source of interaction with the water resources of a region, mainly because it is a sediment contributing area, and that is why Permanent Preservation Areas are tools for environmental protection and conservation involving a water resource. The present work consists in using geoprocessing tools to classify the soil use and occupation of the reservoir General Sampaio basin from remote sensing, and the influence of these uses with the reservoir water quality. The basin has an area of about 1593.28 km², with the Curu River as the main water collector, and Landsat satellite images were used to classify the use and occupation of this area, having the studied years 1997, 2007 and 2017. covering a period of 20 years of temporality. The identification was made with the software QGIS 2.18.0 and the extension Semi-Automatic Classification Plugin (SCP), with the aid of these tools the classification was subdivided into 6 macroclasses (Agriculture, Native Forest, Exposed Soil, Hydrography, Cloud and Shadows), where 10 samples of each were collected in the training stage, and for the classification analysis, the Kappa Index and the Global Accuracy evaluation were used to verify the quality of this work. In the 3 years analyzed the predominance of areas in the Caatinga basin with an average of 81.58% of the area, but it can also be observed that the areas of the Exposed Soil macroclass are predominantly in riparian forest areas, where it can indicate the presence of human activity and also carry serious risks of a sharp erosion in the rivers that supply the dam. The Global Accuracy found for each year was 77.83% for 1997, 99.63% for 2007 and 96.66% for 2017 and Kappa Index of 0.59, 0.99 and 0.91 respectively for the years studied, showing that the classification is close to what can be seen on the spot. Identifying the occupations along the watercourses, and realizing their impacts, reinforces the importance of the APPs areas not only for the preservation of the soil, but also for the maintenance of the water quality along the watershed, requiring public policies. to avoid these irregular occupations, or policies aimed at the recovery of these areas, and validate the use of free geoprocessing software to assist the indicative of these areas.