Resumo

FRAGOSO-SERVON, Patricia; BAUTISTA, Francisco; FRAUSTO, Oscar  e  PEREIRA, Alberto. Characterization of karst depressions (shape, size and density) at 1:50,000 scale and the associated type of flood in the State of Quintana Roo, Mexico. Rev. mex. cienc. geol [online]. 2014, vol.31, n.1, pp.127-137. ISSN 2007-2902.

The occurrence of floods in karst depressions is often crucial for economic activities related to the agriculture, the infrastructure of human settlements and the tourism. The aim of this study was the characterization (size, shape and density) of the karst depressions in the Quintana Roo State, southeastern Mexico, and the type of flood associated. Eighty INEGI (Instituto Nacional de Estadística Geografía e Informática) topographic maps scale 1:50,000 were used to build an altimetry map with equidistance every 10 m. Karst depressions, water bodies and areas subject to flooding were identified. Karst depressions (sinkholes, uvala and poljes) were classified using the following criteria: those with area larger than 1 km² were classified as poljes, otherwise they were classified by their shape using the compactness index: those with values between 1.0 and 1.04 were classified as sinkholes and those with values greater than or equal to 1.3 were classified as uvala. Karst depressions with compactness index between 1.04 and 1.3 were classified using a discriminant analysis. The database was complemented with the identification of exposed water bodies with diameters greater than 10 m and less than 50 m using 2009 LandSat7 and GeoEye imagery, Spot and Global Image from Google Earth by mean of Google Earth Pro v.7.01. A convolution algorithm was used to interpolate a continuous surface of probable karst depressions density. Jenks algorithm was used to split the entire density range into three categories: low, medium and high. We identified 2890 karst depressions occupying an area of 1147.05 km², being uvalas the most abundant and poljes the more extensive. Sinkholes and uvalas are present across the entire state, whereas poljes are present mainly in valleys. The greatest amount of karst depressions is located in the plains; extraordinary flood regime is the most frequent in sinkholes, uvalas and poljes followed by permanent flood regime in sinkholes and uvalas, and temporally flood in poljes. Finally, the differentiation of the territory was achieved through an analysis of the density of negative forms of relief and flooding processes, being this differentiation the central contribution of this study.

Palavras-chave : karst; morphometry; landforms; sinkhole; uvala; poljes; flooding regime; Quintana Roo; Mexico.

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