Assessing Stream Bank Erosion with a Visual Assessment Protocol in Streams Around Drama City, Greece

Stream bank erosion poses significant threats to societal well-being and ecosystem services. Despite its importance, studies in Greece have been limited. This study evaluated stream bank erosion categories using the geographic information system (GIS) and the Bank Erosion Hazard Index (BEHI). Five stream reaches with different characteristics were selected near Drama, Greece. The GIS was used to map the stream and riparian area characteristics and to locate the BEHI sampling plots. The BEHI was employed to classify bank erosion vulnerability. The Categorical Principal Components Analysis (CatPCA) analysis was used to determine the factors that influence erosion. The study reaches, except for one, had high, very high, and extreme stream bank erosion exceeding 28%. Two reaches had greater than 40% of the banks without erosion. Substantial differences in erosion categories (%) were detected due to different fluvio-geomorphologic and anthropogenic pressures. Based on the CatPCA, agricultural and urbanized riparian areas experienced high, very high, and extreme bank erosion. Reaches with perennial flow had limited erosion. In addition, straight reaches had many human interventions. Although mitigation measures had been taken, they have not been effective. Thus, the responsible authorities should consider adopting nature-based solutions to maintain and restore riverine and riparian areas.