OLIVEIRA, L. D.; http://lattes.cnpq.br/5281235061506682; OLIVEIRA, Luan Dantas de.
Résumé:
The Brazilian Northeast is part of the semi-arid regions that make up the globe,
called Caatinga in Brazil. It differs from other seasonally dry tropical forests in the world,
as it has the greatest diversity of species. This region has been populated since the 16th
century, becoming the most populated semi-arid zone. Its inhabitants are concentrated in
places close to water sources, due to water scarcity in certain periods, exploiting natural
resources, and promoting agriculture and livestock. One of the main Hydrographic Basins
in the Northeast is the Piranha-Açu Hydrographic Basin, located in the hinterlands of
Paraibano and Potiguar, which is divided into 11 Sub-Basins, among them we have the
Piancó River Sub-Basin, which has one of the main sources of water resources for the
residents of Sertão da Paraíba. In this context, the present research aimed to classify the
environmental degradation and vegetation cover of the Piancó River Sub-Basin in the
Paraíba hinterland over a period of 30 years. Using Remote Sensing and Digital Image
Processing techniques. To this end, geotechnology was used to identify and monitor areas
in the process of degradation. The methodology was based on a deductive and
comparative approach in the analysis of uses and environmental degradation, allowing
the identification of spatial, temporal and semantic patterns of vegetation and
environmental degradation, generating detailed information on vegetation classes and
levels of degradation of the environment. Piancó River Sub-Basin. To this end, the
climatological average and descriptive statistics of precipitation for each municipality that
make up the Sub-Basin were analyzed. Also, a survey of land use was carried out by
IBGE's SIDRA Platform, observing the agricultural census and the harvested area. For
digital image processing, the free code software QGis was used. Initially, the study site
was characterized and satellite images were acquired from the USGS website. The images
used are those from the TM/LANDSAT-5 satellite and the OLI/LANDSAT-8 satellite.
To classify vegetation and degradation classes, the NDVI corresponding to the years
1993, 2003, 2014 and 2023 was used. In which, through multitemporal orbital images and
applied digital image processing techniques, the characterization was obtained spatio temporal vegetation and degradation levels in the study area. Subsequently, field
observations were made to support the classification and creation of thematic maps. The
Sub-Basin presented, during the analyzed period of 30 years, greater levels of vegetation
in the semi-dense and thin class. As for the degradation classes, in 1993, 42.78% of the
SBRP presented moderately severe levels of degradation. In the years that follow, the
SBRP remains for most of its extent with significant moderate-severe levels. However,
there is an attenuation in the levels of serious degradation, which in 2003, 2014 and 2023
corresponded to 14.79, 12.07 and 7.99%, respectively. At the same time, the moderate
level of degradation increases from 18.14% in 2003 to 62.76% in 2023. The results show
the suppression of vegetation over time, a fact that reverberates in the levels of
degradation obtained. Periods of greater degradation are intrinsically correlated with
periods of greater agricultural activity, indicating a need for adequate management for
the exploration of the Sub-Basin.
