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

Abstract

Abstract:The fluvio-geomorphological processes in meander bends are spatially uneven in distribution. Typically, higher velocities and erosion take place near the outer bank beyond the bend apex, while the inner bend point bar grows laterally towards the outer bank, increasing the bend amplitude. These dynamics maintain the meander evolution. Even though this development is found in meandering rivers independent of soil or environmental characteristics, each river still seems to behave unpredictably. The special mechanisms that determine the rate and occasion of morphological changes remain unclear. The aim of this study is to offer new insights regarding flow-induced morphological changes in meander using a novel study approach. We focused on short-term and small-spatial-scale changes by conducting a spatially and temporally (daily) intensive survey during a flood (a period of nine days) with an ADCP attached to a remotely controlled mini-boat. Based on our analysis, the flood duration and the rate of discharge increase and decrease seems to play key roles in determining channel changes by controlling the flow velocities and depth and the backwater effect may have notable influence on the morphological processes. We discuss themes such as the interaction of inner and outer bend processes and the longer-term development of meander bends.

Spatial variation of flow characteristics in a subarctic meandering river in ice‐covered and open‐channel conditions: A 2D hydrodynamic modelling approach

“…During the last couple of decades, enhancements in methods for analysing these processes have taken place, particularly with regard to flow measurement techniques (Demers et al, ) and modelling approaches (Waddle, ). Despite Acoustic Doppler Current Profiler (ADCP) or Acoustic Doppler Velocimeter (ADV) sensors enabling ice‐covered flow measurements throughout the vertical water column when used through drill holes, the measurements are still mainly made cross‐sectionally, whereas in open channel flow conditions it is possible to acquire measurements at a much greater spatial density, for example, by installing the ADCP on a remote‐controlled platform (Kasvi et al, ). As measurements undertaken through cross‐sectional drill holes cover only a small portion of the river channel area, numerical simulations – calibrated based on the more limited measurement data – could give insight into the spatial variation of flow characteristics more widely.…”

The Effect of Cylindrical and Triangular Pillars on Changes in Water Levels at Channel Bends

“…The increase in the maximum water height is directly proportional to the average water velocity, gravity force, river width, bend radius, and superelevation coefficient [4,15].…”

“…The surface was affected by the mean water velocity, gravity force, river width, bend radius, and the superelevation coefficient [4,15]. Considering these factors, this study aimed to examine the effect of cylindrical and triangular pillars on changes in water level at the channel bend.…”

Spatial and Temporal Variability of Bank Erosion during the Period 1930–2016: Case Study—Kolubara River Basin (Serbia)

“…A map of the active tectonic movements of the Kolubara's basin shows that almost the whole area of the lower part of the Kolubara valley is slowly sinking under tectonic movements [27,29] of the southern part of the Pannonian Basin [3,4,[30][31][32]. It is well known that the discharge represents the main active force for river bed modeling [19,[33][34][35]. The Kolubara River has the highest coefficient of discharge variation in comparison to other larger river basins in Serbia, and has a misbalanced ratio between high and low waters [36].…”