A channel shifting GIS toolbox for exploring floodplain dynamics through channel erosion and deposition

Assessing spatial patterns and the long-term evolution of river channel planforms is needed for understanding river behaviour and change. GIS tools exist to explore channel planform characters in space and time, but none yet exist to characterise channel shifting and associated floodplain dynamics. The paper presents the applications of a new toolbox that can work as a standalone (e.g., the ArcGIS Standalone channel shifting toolbox - SCS Toolbox) or linked to existing toolboxes such as the fluvial corridor toolbox (FCT). It complemented a wide palette of tools and approaches that are used for understanding and conceptualising river-style and fluvial continuum. Vectorised channel polygons are used to detect the basic morphometric processes between 2 consecutive observation dates as channel erosion, deposition and lateral movement orientation. The toolbox application supports the evaluation of spatial dynamics and lateral erosion by identifying channel migration and reach scale mobility. It also includes floodplain statistics based on combined LiDAR information, where height above the channel and vegetation canopy height are generated. The toolbox was tested on five river systems, some being sinuous (Ain and Topľa Rivers), meandering (Ondava River) or braided-wandering (Belá River). These examples illustrate how spatio-temporal analyses of river channel shifting are used for process-based understanding of channel evolution, in-channel dynamics, lateral movement and floodplain-channel interactions.