Estudo da dinâmica dunar na região da lagoa do Portinho utilizando dados mapbiomas

Abstract

Coastal dynamics are caused by anthropic and natural elements. This situation is no different when it comes to the coast of Piauí. The trade winds affect this Northeast region and, therefore, it experiences intense dune geodynamics that can lead to sand invasions in roads, residences, and water areas. An example is Lagoa do Portinho, located on the border of the municipalities of Parnaiba and Luís Correia, in the state of Piauí. We can see that the dunes are moving from the coast to the interior of the continent. In recent years, this displacement has intensified. We used remote sensing in this work to quantitatively investigate changes in the dunes present in the natural landscape of the Lagoa do Portinho region, from 1985 to 2020. We used the MapBiomas tool, collection 6, to process in the cloud satellite images from Landsat sensors 5, 7 and 8, in order to generate the land use and land cover classification and evaluate the transformations every 5 years. We cropped the Lagoon area in satellite images using water mass shapefiles provided by IBGE, with a 2 km buffer. We used the free software QGis 3.22 to produce the maps. The results revealed that the area occupied by aeolian sediments increased by 0.47 km² or 465,300 m² or 9.31% between 1985 and 2020, with an annual average of 13,294 m², migrating from the Northeast to the Southeast, following the direction of the trade winds that affect this region. During this period, the dunes expanded occupying an area of 1.18 km², while the retraction of the dunes was verified in 0.71 km². In 2019, the State of Piauí granted the region the status of Area of Relevant Ecological Interest (ARIE). We considered the elaboration and dissemination of the management plan by SEMAR, as well as the sending of resources to the region. Likewise, the promotion of debates and actions with the local community and the introduction of signs informing about the conscious use of the environment by workers and users.