Using the Relative Elevation Models to delimit the floodplain level development: The case of the braided-wandering Belá River, Slovakia

Abstract The Belá River is a specific submountain river running through the Liptov Basin in the Slovak Carpathians. Its transformation from a braided to a braided-wandering system and degradation including incision of the river system has been observed since the middle of the 20 th century. These processes have created a complex system of floodplains with development stages. For their identification, the Relative Elevation Model normalizing absolute floodplain elevation to the river channel changes has been established. Three models have been prepared, from the channel bottom and water level elevation gauge by GPS, and the water level elevation by LiDAR. Based on the resulting models, the floodplain was identified and delineated to an active or potentially active floodplain, to an inaccessible floodplain spread behind artificial structures, and to a perched floodplain beyond the reach of the river. Spatial statistics, including “Hot spot analysis” and “Cluster and outlier analysis” have been used to identify recent river floodplain formation from 1949 to 2018, caused by simplification and incision of the Belá River. The unique aspect and contribution of the research lies in implementing and comparing the Relative Elevation Models and linking them to floodplain age.