Analysis of two small semi-mountainous catchments in central Evia island, Greece, highlights the advantages of Unmanned Aerial Vehicle (UAV) and Terrestrial Laser Scanning (TLS) based change detection methods. We use point clouds derived by both methods in two sites (S1 & S2), to analyse the effects of a recent wildfire on soil erosion. Results indicate that topsoil’s movements in the order of a few centimetres, occurring within a few months, can be estimated. Erosion at S2 is precisely delineated by both methods, yielding a mean value of 1.5 cm within four months. At S1, UAV-derived point clouds’ comparison quantifies annual soil erosion more accurately, showing a maximum annual erosion rate of 48 cm. UAV-derived point clouds appear to be more accurate for channel erosion display and measurement, while the slope wash is more precisely estimated using TLS. Analysis of Point Cloud time series is a reliable and fast process for soil erosion assessment, especially in rapidly changing environments with difficult access for direct measurement methods. This study will contribute to proper georesource management by defining the best-suited methodology for soil erosion assessment after a wildfire in Mediterranean environments.

Soil changes, including landslides and erosion, are some of the most prominent post-fire effects in Mediterranean ecosystems. Landslide detection and monitoring play an essential role in mitigation measures. We tested two different methodologies in five burned sites with different characteristics in Central Greece. We compared Unmanned Aerial Vehicles (UAV)-derived high-resolution Digital Surface Models and point clouds with terrestrial Light Detection and Ranging (LiDAR)-derived point clouds to reveal new cracks and monitor scarps of pre-existing landslides. New cracks and scarps were revealed at two sites after the wildfire, measuring up to 27 m in length and up to 25 ± 5 cm in depth. Pre-existing scarps in both Kechries sites appeared to be active, with additional vertical displacements ranging from 5–15 ± 5 cm. In addition, the pre-existing landslide in Magoula expanded by 8%. Due to vegetation regrowth, no changes could be detected in the Agios Stefanos pre-existing landslide. This high-spatial-resolution mapping of slope deformations can be used as landslide precursor, assisting prevention measures. Considering the lack of vegetation after wildfires, UAV photogrammetry has great potential for tracing such early landslide indicators and is more efficient for accurately recording soil changes.

This work focuses on the spatial evolution of urban flooding phenomena in Athens metropolitan area, in Greece. The study examines the locations of flood-related damages and fatalities in Athens in 1880–2010, in comparison with the city’s evolution, to identify possible changes in their spatial distribution. GIS software was used to develop a spatio-temporal database storing information on the location and timing of these flood-related incidents. The database was then used to determine and quantify spatio-temporal changes of flooding in the city. Results showed a gradual migration of areas subject to flooding from the central to the western part of Athens and finally to the northwestern and southern suburbs. This migration was accompanied by a significant increase of incidents in the newly built parts of the city and a simultaneous decrease at the oldest parts, following closely the city’s spatial expansion over the study period. In addition, the study was able to identify and delineate particular parts of the city that experienced an increasing trend of flood incidents during the last decades and should be given priority in future flood risk mitigation actions.

Thorough faunal (benthic foraminifera, ostracods, molluscs) and palynomorph analyses as well as magnetic susceptibility measurements performed on the Piraeus coastal plain sedimentary sequences have shed light on the paleoenvironmental evolution of the area since ca. 9000 cal BP. Benthic and palynomorph assemblages along with magnetic susceptibility suggest a typical lagoonal environment with significant freshwater inputs at the eastern part of the plain after 8700 cal BP. Between 7500 and 5400 cal BP, microfaunal assemblages, mollusc fauna and magnetic susceptibility suggest a shallow marine paleoenvironment, with Piraeus forming a tied island in the center of the bay. Since ca. 4800 cal BP a closed oligohaline lagoon is evidenced in the western part of the Piraeus plain further developed to a marsh after 2800 cal BP, while a coastal environment associated with the fluvio-deltaic system of Kifissos and Korydallos Rivers is continually developing to the west. Signs of cultivation and grazing activities in the area are evidenced since the Early Bronze Age, culminating during the Classical Period. A comparison with a well-dated marine record, recovered from the nearby shallow Elefsis Bay, provides a reasonable estimation of ~5 mm/yr for the absolute sea level rise rate in the inner Saronikos Gulf during the Mid-Holocene.

Pallikarakis, A.; Triantaphyllou, M.V.; Papanikolaou, I.; Dimiza, M.D.; Reicherter, K., and Migiros, G., 2018. Age constraints and paleoenvironmental interpretation of a borehole sedimentary sequence along the eastern part of the Corinth Isthmus, Greece. Borehole Bh-3, located at the eastern part of the Corinth Isthmus (Greece) in a highly active extensional tectonic environment, is studied in detail. The lithology of the 70-m-long borehole is described, and 55 samples extracted from the core are analyzed for their micropaleontological content. Quantitative analysis of foraminiferal fauna assemblages, along with magnetic susceptibility measurements, indicates alternations between different paleoenvironments ranging from upper shoreface and fluvial-terrestrial to lagoon and shallow marine. The borehole site regional paleodepth was estimated, ranging from a few meters to ∼40 m on the basis of foraminiferal assemblages within the borehole, and the vertical stacking of the facies was interpreted as t...