Riparian ecosystems in urban environments are usually degraded. Their sustainable management can reduce water pollution, mitigate climate change while providing recreation opportunities. This study assessed the current condition of the streams/torrents and their riparian areas in the city of Drama in Greece. In addition, practices to improve their functionality and enhance community awareness were recommended. A spatial database of the wider urban setting including suburbs and rural areas (weather, land cover, soils, roads, protected areas, riparian areas, etc.) was developed within GIS. The datasets were then inputted in a hydrologic model to simulate the water balance and stream discharge in the main urban streams and torrents. Field measurements of stream water discharge, and vegetation and stream channel conditions were undertaken using two visual protocols. The results of the protocols indicate that most streams/torrents and their riparian areas are of low ecological quality. Nature-based solutions were recommended to improve their ecological quality. In addition, the implementation of Eco-Routes was recommended to enhance the awareness of their importance and to promote their sustainable management. Overall, the urban streams/torrents and riparian ecosystems of Drama are degraded and innovative management practices should be implemented to conserve them and feature their ecosystem services.

The accuracy of photogrammetry for geohazards monitoring has improved within the last years because of the “drone revolution”. This study is an attempt to perform morphometric measurements in a landslide event that took place near the village Nea Zichni in Northern Greece. The DJI Mavic 2 Pro was selected to capture orthoimages of the entire area including the landslide event but also other adjusted disaster phenomena. The images were loaded in the commercial software Pix4D in order to produce orthomosaics and digital surface models of the area. The georeferenced results were further analyzed in ArcGIS in order to digitize and estimate the morphometric parameters of the landslide, such as its area and volume, but also to detect cracks and plot the tensile cracking directions. We conclude that the methodology and produced outputs are crucial for the responsible authorities to detect, monitor and mitigate natural disasters such as landslide events and other mass movements. The best practices to control mass movements are nature-based solutions such as soil bioengineering and proper vegetation cover assisted by engineering measures. Finally, our goal is to frequently monitor the landslide phenomenon in order to determine its evolution.

The development of methodologies for analyzing the evolution and pressures exerted on the river channel network is one of the main concerns of researchers today. The assessment of natural or artificial changes of river channels and beds plays an important role in environmental protection, but also in the implementation of integrated water resource management plans. Given the episodic and dynamic nature of river bank and bed erosion, along with the difficulty of reaching certain reaches, a methodological approach that uses aerial imagery, initially from satellite sources and afterwards from unmanned aerial vehicles, is proposed. This approach was utilized in a perennial river in Romania but also in an ephemeral torrent channel in Greece, in order to test the prevalent types of hydrographic network in the Mediterranean and Black Sea region. The methodology used was able to identify the location and the volume of the bed material extracted and the time frame in which it occurred. These encouraging results showcase an accurate but also relevantly low-cost monitoring method for illegal anthropogenic activities that can be easily adopted by the responsible authorities. The adoption of the method will contribute to the more efficient monitoring of river protection, by accurately and timely identifying areas of illegal river bed extraction that will enable authorities to enforce European Union and national legislation.

Capturing and recording fluvio-geomorphological events is essential since these events can be very sudden and hazardous. Climate change is expected to increase flash floods intensity and frequency in the Mediterranean region, thus enhancing such events will also impact the adjacent riparian vegetation. The aim of this study was to capture and record the fluvial-geomorphological changes of the torrent bed and banks and flood debris events with the use of UAV images along a reach of Kallifytos torrent in northern Greece. In addition, a novel approach to detecting changes and assessing the conditions of the riparian vegetation was conducted by using UAV images that were validated with field data based on a visual protocol. Three flights were conducted using the DJI Spark UAV. Based on the images collected from these flights, orthomosaics were developed. The orthomosaics clearly identified changes in the torrent bed and detected debris flow events after major flood events. In addition, the results on the assessment of riparian vegetation conditions were satisfactory. Utilizing UAV images shows great potential to capture, record, and monitor fluvio-geomorphological events and riparian vegetation. Their utilization would help water managers to develop more sustainable management solutions based on actual field data.

The alleviation of landslide impacts is a priority since they have the potential to cause significant economic damage as well as the loss of human life. Mitigation can be achieved effectively by using warning systems and preventive measures. The development of improved methodologies for the analysis and understanding of landslides is at the forefront of this scientific field. Identifying effective monitoring techniques (accurate, fast, and low cost) is the pursued objective. Geographic Information Systems (GISs) and remote sensing techniques are utilized in order to achieve this goal. In this study, four methodological approaches (manual landslide delineation, a segmentation process, and two mapping models, specifically object-based image analysis and pixel-based image analysis (OBIA and PBIA)) were proposed and tested with the use of Unmanned Aerial Vehicles (UAVs) and data analysis methods to showcase the state and evolution of landslides. The digital surface model (DSM)-based classification approach was also used to support the aforementioned approaches. This study focused on streamside landslides at research sites in three different countries: Greece, Romania, and Turkey. The results highlight that the areas of the OBIA-based classifications were the most similar (98%) to our control (manual) classifications for all three sites. The landslides’ perimeters at the Lefkothea and Chirlesti sites showed similar results to the OBIA-based classification (93%), as opposed to the Sirtoba site, where the perimeters of the landslides from OBIA-based classification were not well corroborated by the perimeters in the manual classification. Deposition areas that extend beyond the trees were revealed by the DSM-based classification. The results are encouraging because the methodology can be used to monitor landslide evolution with accuracy and high performance in different regions. Specifically, terrains that are difficult to access can be surveyed by UAVs because of their ability to take aerial images. The obtained results provide a framework for the unitary analysis of landslides using modern techniques and tools.

The study attempts to monitor geomorphological changes (e.g., erosion/deposition) with innovative tools at a typical Mediterranean torrent. The torrent’s geomorphological conditions are studied for an entire affected stream reach. The investigation utilizes two different environments/point views: (a) traditional terrestrial and (b) innovative aerial. The traditional methods include erosion pins at streambanks and field cross-section measurements of the stream channel. For the innovative methods, utilizing an unmanned aerial vehicle, in order to monitor the geomorphologic changes in the entire reach during different days over the last 3 years (2020–2022), there was a total of six flights. The results from innovative methods showcase the episodic nature of stream channel changes since erosion and deposition were captured during the different monitoring periods. Even during one flight in one cross-section, the stream bed and two banks in many cases experienced different changes. The significant erosion and deposition recorded showcase the disequilibrium in the torrent. In addition, the impact of the anthropogenic structure (Irish bridge) is evident, since upstream, more substantial deposition was recorded compared to downstream. The similarity of the results between the innovative method and the traditional methods indicates the method’s effectiveness and the potential usefulness in using UAV images for stream bank and bed monitoring. One of the biggest advantages is the ability to monitor the entire reach at substantially lower costs and time compared to the traditional methods. Still, more testing needs to be conducted in different stream and river environments to better refine the method in order to be adopted by land and water managers to be used for stream and river monitoring.