Detecção de mudanças em um campo de dunas móveis utilizando sensoriamento remoto no Município Aracati, Estado do Ceará

Abstract

The coastal plain of Baixo Jaguaribe in the Municipality of Aracati – CE is a geographic space with potential for the exploitation of wind energy, but any undertaking carried out on the plain and the field of mobile dunes can affect the balance of the coastal dynamics. As of 2008, one of the first large wind farms was built in the state of Ceará, a pioneering condition that brought, in addition to producing energy from a renewable source such as wind, some socio-environmental conflicts in nearby communities and local impacts on the mobile dune field whose alterations affect dune dynamics and the transport of sedimentary material. The objective of this work was to identify the changes in the mobile dune field in the coastal plain of Baixo Jaguaribe between 2002 and 2013, a time interval that includes before and after the installation of the wind farm, to verify if there was any change in the displacement dunes after the installation of the wind farm. In the multitemporal analysis, images from the SPOT 5 sensor were used on dates related to the dry period. The methods applied for the detection of changes were the spectral mixture analysis (AME) and difference bands math between images. A temporal comparison was made between the AME dune components and the linear measurements of displacement between dunes in 21 chosen locations, identifying locations of dune fixation, reduction of dune displacement and locations with normal advance. A drop in dune displacement was observed from 2011 and some points where the road works as a barrier reducing the displacement of the dune and/or anthropic actions such as fixation with coconut palm straw contributes to the process of dune fixation. This information was validated using QuickBird images and the drawing of dune fronts, confirming that the displacement values are within the estimates of the applied method. The implementation of wind farms on the mobile dune field, behaves as a barrier that causes changes in the morphology of the dunes and their natural displacement dynamics. The use of remote sensing tools and images with high spatial resolution help to assess impacts and recommend alternative locations, in favor of better planning of geographic space.