Morphological variations in mountain streams as proxy for sediment transport: A case study

Sediment transport in rivers is posing a hazard to infrastructures and cities built along the river courses, especially in mountain areas. Awareness about this topic raised in the last decade and even the European Flood Directive in 2007 stated that particular attention should be devoted to “areas where floods with a high content of transported sediments and debris floods can occur”. Authors are monitoring sediment transport in a 24km2 basin in Alps, Northern Italy, since 2016. This stream was surveyed multiple times during each summer season and showed rapid changes in morphology due to slow accumulation and sudden depletion of sediments inside the riverbed. Topographical surveys with drones and photogrammetric campaigns have been used to assess variation in bed elevation and volumetric changes. Nevertheless, these techniques do not give any insight in morphological changes of the river that are fundamental since they influence sediment transport as long as flood hazard and the ecology of the river’s ecosystem. The work presents a detailed photographical survey of a natural river stretch were same pictures were taken along three years highlighting morphological evolution of the stream and cyclical changes. A direct connection between flow rates, rainfalls and evolution is looked for and some connection were found and are presented.