Elaboration of Geotechnical Thematic Maps in Urban Areas

Abstract

In urban areas it is difficult to access natural terrain due to strong human intervention. Therefore, any exposure of the natural terrain is considered an important source of geological and geotechnical data collection. The Geographic Information Systems (GIS) has been responsible to provide great development in geotechnical cartography, particularly in urban environment, using geographic databases and new analysis tools. Our goal is to create a geographical database that will allow and/or improve the elaboration of geotechnical thematic maps, using cartographic data of open platforms combined with free and open source GIS software. In the presented study our focus was related with the identification of the granite alteration degree...Through the geographical database, along with the geological map of the study area, the areas related to the degree of granite alteration were identified and delimited. The data were collected through “Street View” which results from the integration of a specific module in the GIS software (QGIS). The obtained data were validated by direct observation and were photographically recorded. This approach proved to be an effective method, with no significant differences when compared with direct observations. The methods’ limitations are the quality of some “Street View” images, and the existent subjectivity related to the observer in the identification of the degree of alteration of the rocky massif. Its advantage is to reduce the data collection’s time and the possibility of comparing the same place at different time points.