Empirical Modeling of Spatial 3D Flow Characteristics Using a Remote-Controlled ADCP System: Monitoring a Spring Flood

Abstract

The use of acoustic Doppler current profilers (ADCP) for measuring streamflow and discharge is becoming increasingly widespread. The spatial distribution of flow patterns is useful data in studying riverine habitats and geomorphology. Until now, most flow mapping has focused on measurements along a series of transects in a channel. Here, we set out to measure, model and analyze the 3D flow characteristics of a natural river over a continuous areal extent, quantifying flow velocity, 3D flow directions, volumes, water depth and their changes over time. We achieved multidimensional spatial flow measurements by deploying an ADCP on a remotely-controlled boat, combined with kinematic GNSS positioning and locally-monitored water level data. We processed this data into a 3D point cloud of accurately positioned individual 3D flow measurements that allows the visual analysis of flow velocities, directions and channel morphology in 3D space. We demonstrate how this allows monitoring changes of flow patterns with a time series of flow point clouds measured over the period of a spring flood in Finnish Lapland. Furthermore, interpolating the raw point cloud onto a 3D matrix allows us to quantify volumetric flow while reducing Water 2015, 7 218 noise in the data. We can now quantify the volumes of water moving at certain velocities in a given reach and their location in 3D space, allowing, for instance, the monitoring of the high-velocity core and its changes over time.

Flow Patterns and Morphological Changes in a Sandy Meander Bend during a Flood—Spatially and Temporally Intensive ADCP Measurement Approach

“…They have many of the same disadvantages as traditional methods-namely the fact that most of the river reach is not surveyed, and thus the results are highly dependent on the interpolation analysis of the ADCP transect data. Therefore, recent attempts have been made to map the flow field in high resolution with horizontally continuous ADCP data [33][34][35]. The horizontally continuous approach The sub-bend-scale processes (including erosion at the point-bar head or convex bank beyond the apex and deposition over the point-bar tail) are key factors in the meander evolution, leading the bend from one phase to another.…”

“…Therefore, recent attempts have been made to map the flow field in high resolution with horizontally continuous ADCP data [33][34][35]. The horizontally continuous approach demonstrated by Flener et al [33] is applied in this study for the first time to study flow patterns and morphological changes in a meander bend.…”

“…Water 2017, 9, 106 6 of 19 demonstrated by Flener et al [33] is applied in this study for the first time to study flow patterns and morphological changes in a meander bend.…”

“…Recently, there have been attempts to survey the flow field and morphology in high resolution with spatially continuous Acoustic Doppler Current Profiler (ADCP) data [33][34][35]. Flener et al [33] demonstrated a measurement approach in which the ADCP device was attached to a remotely controlled mini-boat that was equipped with RTK-GNSS. The approach allowed for spatially dense flow and bed-level measurements in a relatively short period of time.…”

“…However, no scientific research has yet exploited spatially continuous ADCP data to analyze the flow patterns and morphological changes of a meander bend. Thus, the data set collected and analyzed by Flener et al [33] is used in this paper.…”