ASSESSMENT OF LANDSCAPE BY PHOTOGRAMMETRY PROXIMITY UAV SURVEY TECHNIQUE: A CASE STUDY OF AN ABANDONED MINE SITE IN THE FURTEI AREA (SARDINIA-ITALY)

In the past open pit excavations often created risks and environmental impacts derived by the mining activities that deeply changed the landscape. In South Sardinia the Furtei area, at Monte Porceddu, is a typical example of kaolinitic clays open pit mine, where exploitation activities have deeply altered the original landforms. After mining closure this site was totally abandoned and represents an extremely dangerous place. Nowadays the possibility to recovering this site depends on the knowledge of local geolithological asset and the hydrological characteristics of the sub-surface drainages. In this paper we present a method based on a detailed photogrammetric UAV survey to generate multiple high quality dense digital surface models (DDSMs) in order to provide basic terrain analysis. The photogrammetric UAV method allows to survey risky areas with reliability, accuracy and safety and, after some post-elaboration procedures, to point out complex geometric surfaces characteristics related to geological and hydrological informations.