High resolution mapping of riffle-pool dynamics based on ADCP and close-range remote sensing data
Jouni Salmela; Petteri Alho; Elina Kasvi
https://urn.fi/URN:NBN:fi-fe2021042717290
Tiivistelmä
Present development of mobile laser scanning (MLS) and close-range photogrammetry with unmanned aerial
vehicle (UAV) enable us to create seamless digital elevation models (DEMs) of the riverine environment. Remotecontrolled
flow measurement platforms have also improved spatio-temporal resolution of the flow field data. In this
study, acoustic Doppler current profiler (ADCP) attached to remote-controlled mini-boat, UAV-based bathymetry
and MLS techniques were utilized to create the high-resolution DEMs of the river channel. These high-resolution
measurements can be used in many fluvial applications such as computational fluid dynamics, channel change detection,
habitat mapping or hydro-electric power plant planning. In this study we aim: 1) to analyze morphological
changes of river channel especially riffle and pool formations based on fine-scale DEMs and ADCP measurements,
2) to analyze flow fields and their effect on morphological changes. The interest was mainly focused on reach-scale
riffle-pool dynamics within two-year period of 2013 and 2014. The study was performed in sub-arctic meandering
Pulmankijoki River located in Northern Finland. The river itself has shallow and clear water and sandy bed sediment.
Discharge remains typically below 10 m3
s
−1 most of the year but during snow melt period in spring the
discharge may exceed 70 m3
s
−1
. We compared DEMs and ADCP measurements to understand both magnitude
and spatio-temporal change of the river bed. Models were accurate enough to study bed form changes and locations
and persistence of riffles and pools. We analyzed their locations with relation to flow during the peak and
low discharge. Our demonstrated method has improved significantly spatio-temporal resolution of riverine DEMs
compared to other cross-sectional and photogrammetry based models. Together with flow field measurements we
gained better understanding of riverbed-water interaction
Kokoelmat
- Rinnakkaistallenteet [19206]