LVRS Consultancy can organise field surveys to measure flow velocities, sediment transport, bathymetry in rivers, estuaries and coastal seas.
Accurate morphological predictions require input data based on field measurements focussing on:
- velocity and sediment concentration profiles (mud, silt, fine sand);
- insitu settling velocities of mud;
- bed form, bed form migration and bed-load transport.
In river and tidal flows, these parameters can most accurately be determined from online insitu measurements using a small underwater carrier with instrumentation operated from a survey vessel.
The instrumentation consists of:
- electromagnetic and acoustic current sensors (Valeport; Nortek);
- optical concentration sensors (OBS; Partech);
- CTD sensors for conductivity, temperature and depth (water pressure);
- echosounder and digital compass;
- pump intake nozzles for water-sediment samples (calibration samples);
- insitu settling tube.
- small grab sampler for bed matrial samples;
- dual frequency echosounders (210/33 KHz) for fluid mud detection;
- acoustic sensor for wet bulk density of fluid mud layers (Sonidense; wiertsema.nl)
The measurement of wave height, velocity and suspended sediment concentrations during storms in coastal seas require fully automated bed frames/tripods with datalogging instrumentation. These types of measurements are less accurate as regards sediment transport because pump calibration samples cannot be taken, while also the position of the sediment sensors with respect to the dynamic bed surface is uncertain.
Reference: Manual Sediment Transport Measurements; Van Rijn 2012
Bed and suspended load sampler Small suspended load sampler
Near-bed suspended load sampler Sonidense fluid mud density