River instability
Fluvial process such as channel adjustment, intensive meandering, and river bank erosion can lead to negative impacts.
“The hazard of watercourses is mainly connected with occasional and exceptional changes of their water stages occurring during extra-bank flow rather than with the changes periodically generated by ordinary flow. The [river] channel can be considered a fluvial form constantly adjusting itself to changes occurring at times along its course in the short and long term, whilst the alluvial plain behaves as a form in occasional adjustment” [M.Panizza, F.Maraga, 1996].
Many rivers in mountain and piedmont areas including braided streamflows are very dynamic, with intensive erosion and deposition and rapid adjustments to channel form. Evolution of meandering streams is accompanied by intensive bank erosion. In many cases bank erosion is significantly controlled by the resistance-to-erosion properties of alluvium (or bedrock), the presence and type of riparian vegetation, dredging and bank protection.
The main types of river channel instability are:
- rapid adjustment of channel form
- intensive meandering and bank erosion
- planimetric variations of the watercourse
- post-flood changes in topography due to intensive erosion and deposition
- reactivation of abandoned channels
- intensive channel deformations due to dredging, dam and embankment construction etc.
Zesmill specialists use state-of-the-art methodology and geospatial data to determine risks associated with river bank erosion and channel-related hazards. Our primary objective is to identify the mechanisms controlling channel form, sediment supply, erosion, and deposition. To investigate these processes, we use
- hydrological measurements (streamflow width and depth, water level, flow velocity, discharge measurements etc.)
- detail geomorphologic and litho-stratigraphic studies of river channel, banks, bars, abandoned channels, and the floodplain including field mapping, alluvium drilling and facies analysis
- bed and bank material sampling and soil testing (carried out by subcontractors)
- remote sensing technologies including multi temporal image analysis and LIDAR
- hydrologic modeling.