Aeolian processes in drylands often transcend into sand encroachment, a common form of land degradation. Highly reflective desert features, hence sandy areas, often cause spectral confusion, and mapping through remote sensing techniques can be challenging. This work aims at designing an efficient classification method that minimises spectral confusion of desert features, hence two types of sandy areas. Moreover, we employ land cover (LC) change detection over the last 30 years. The extraction and spatiotemporal variations of LC and sand encroachment areas in the Dahar-Jeffara Medenine site (southeastern Tunisia) are assessed by employing Landsat imagery (1984 and 2014), a 30 m digital elevation model of Shuttle Radar Topography Mission (SRTMGL 1 arc second), field data and X-ray diffraction analyses of sand samples. Five new spectral indices were designed and employed in a Decision Tree (DT) classifier for the extraction of 11 LC classes, including two different types of sandy areas. The DT map yielded an overall accuracy of around 89%. Change detection results showed substantial change in several landscape components and an increase of sand units by 29% within the Jeffara-Medenine plain over the last three decades. Geomorphological observations and multi-temporal, spectral and mineral analyses indicate a main, possible in-situ source area of sand.

In this paper, we report on the first project on the promotion of urban geoheritage in Cagliari, the capital of the Autonomous Region of Sardinia (Italy). We briefly address the history of geo-palaeontological research in the city area and outline the main phases of development in the history of Cagliari’s geo-palaeontological museum. Geotourism is an efficient method of bringing geosciences to a wider audience. For this project, we compiled a geoitinerary of the main lithotypes and fossils present within the urban territory. Miocene lithotypes are the most important materials in the edification of the Cagliari’s old town, and in the past, the quarrying activity favoured the geology knowledge of the area. The presence of abandoned quarries and natural outcrops in parks, public gardens, on the nearby coastline, and also of fossils exposed in ashlars of historic buildings, made Cagliari an excellent example to valorise the geo-palaeontological heritage using geotourism. This project showcases the importance of knowledge transfer and non-technical communication methods by converting highly technical aspects into accessible and engaging information dissemination to a wide range of audience types, including non-specialised ones.