Data in Portuguese
Location of areas susceptible to mass and flood gravity movements, classified as high, medium and low, mainly related to mass movements and floods, in Brazilian municipalities prioritized by the Federal Government.
The information generated for the preparation of the letter is in accordance with the scales 1: 50,000 and 1: 25,000.
The zoning presented is basic level and is based on spatially predisposable natural factors, obtained through compilation and treatment of available secondary data and field validation.
The areas indicated in the map indicate areas of predominance regarding the analyzed process. They do not indicate the trajectory and range of the mobilizable materials, nor the interaction between the processes. The relative classification (high, medium, low) points out areas where the propensity to process is higher or lower compared to others. Within the zones there may be areas with distinct classes, but their identification is not possible due to the scale of the chart. On land, the transition between classes tends to present itself more gradually. Low susceptibility does not mean that processes can not be generated in their domain, since human activities can modify their dynamics. The presence of features associated with processes can locally change the class indicated.
In order to contribute to the interpretation of the susceptibility classes to mass and flood movements, maps of relief patterns are elaborated for each municipality under analysis. This product is elaborated in a standardized way based on the application of the Relief Pattern Library , which aims to provide a geomorphological compartmentalization proposed by the methodology of mapping the susceptibility of semi-metric scale municipalities (1: 25,000). The mapping of relief patterns represents, in general terms, the 3rd hierarchical taxon of the methodology of geomorphological mapping proposed by Ross (1992). In some cases, relevant relief features were mapped to scale mapping in greater detail.
The cartographic bases present scales varying from 1: 250,000 to 1: 25,000, occasionally adjusted to the 1: 25,000 scale (drainage network, highways and urban slick) and / or modified by CPRM to meet project interests. The IBGE, through its Geosciences Directorate, is performing the validation of the geometric quality of the cartographic mapping of the bases derived from the RADAR, airborne and digital aerophotogrametry surveys, in order to guarantee the accuracy necessary for the elaboration of the susceptibility charts. This validation work consists of surveys of control point meshes in the field and subsequent elaboration of geostatistical analysis reports.
The images used in the interpretations are from RapidEye (resolution 5.0 m), RADAR orthoimages (resolution 2.5 m) and orthophotos (resolution from 0.39 to 10 m). Digital elevation and terrain models from RADAR (1.0 to 10 m resolution), aerial photogrammetry (1.0 to 20 m resolution) and TOPODADA-INPE (30 x 30 m resolution) were used.
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