A influência das dolinas na vulnerabilidade do aquífero Urucuia, Chapadão Central - oeste da Bahia, Brasil

• Autor(a) principal: Silva, Gisele Bispo da
• Data de Publicação: 2023
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFG
• dARK ID: ark:/38995/0013000000z2p
• Texto Completo: http://repositorio.bc.ufg.br/tede/handle/tede/12762
• topic: Mapeamento de dolinas; Modelagem de vulnerabilidade; Método COP; Dolines mapping; Vulnerability modeling; COP method; CIENCIAS EXATAS E DA TERRA::GEOCIENCIAS::GEOGRAFIA FISICA::HIDROGEOGRAFIA

The karst system is generally known for developing in carbonate environments. Formed by the interaction between acidified water and soluble rocks, it sculpts the relief into different types and shapes by the process of dissolution. Studies have pointed out the development of karstic systems in siliciclastic rocks, such as sandstones, for example, and, differently from carbonates, in these rocks the main karst formation process is piping. Among the morphologies developed by karst, whether in carbonates or not, the dolines are the main surface features, also known as closed depressions, whose size varies from a few meters to hundreds of meters in depth and diameter. Due to this difference in size and shape, identifying them in the middle of distinct landscapes or in very large areas is sometimes difficult. Dolines are fragile features and are a connection between the surface and the underground. Because of this, they can act directly as potential contaminants of groundwater. For reason of having evidences of dolines developed in sandstones in Chapadão Central - West of Bahia, the area being directly affected by agricultural activities and being under domain of the Urucuia Aquifer System (SAU), the research had as objective to identify and to validate these features by means of mapping technique using Digital Elevation Model (DEM), with SRTM data - 30m and, by morphometric analysis and to relate them with the potential of contamination of the aquifer by means of the evaluation of intrinsic vulnerability applied by the COP method. The methodology that used the MDE for the identification of dolines presented good results for Chapadão. The database was adjusted to avoid possible errors, thus allowing the extraction of information from 109 dolines with precision. It is a low cost methodology and can be applied in areas of large territorial extension. The COP method also presented satisfactory results for Chapadão, showing that the area presents the 5 vulnerability classes (Very High, High, Moderate, Low and Very Low). The most vulnerable classes, considered as very high and high, are spatially distributed in the western portion of the Chapadão, corresponding directly with the presence of the dolines. This indicates that the use and occupation of the lands of Chapadão without an adequate environmental management can impact the dolines superficially and lead to a contamination of the Urucuia aquifer.