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Remote Real-time Riprap Protection Erosion AssessmenT on large rivers

Authors:
Gordon Gilja at University of Zagreb Faculty of Civil Engineering
Gordon Gilja
  • University of Zagreb Faculty of Civil Engineering
Antonija Harasti at University of Zagreb Faculty of Civil Engineering
Antonija Harasti
  • University of Zagreb Faculty of Civil Engineering
Kristina Potočki at University of Zagreb Faculty of Civil Engineering
Kristina Potočki
  • University of Zagreb Faculty of Civil Engineering
Matej Varga at ETH Zurich
Matej Varga
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Abstract

Large number of bridges in Europe is at the end of their life span, while the frequency of occurrence for extreme climatic events, driven by climate change, is increasing. Floods influence morphodynamic changes in the riverbed, such as scouring of the riverbed next to the bridge substructure, that can undermine the overall stability of the bridge. Placement of riprap protection around bridge piers is an approach that doesn't solve scouring problem, it rather displaces the scour hole elsewhere in the river channel, where its location is unknown because it is formed in the interaction between the flow and the structure, in site-specific conditions. Traditional approach to scour monitoring is effective only if surveys are conducted during the flood conditions, while the data acquired post-flood can underestimate the full potential of flood hazard. Detailed field surveys of hydraulic parameters during floods are essential in the understanding of morphodynamic evolution of the river channel, but are often scarce because they are time-consuming and require extensive resources (e.g. the survey equipment). Therefore, the majority of research was conducted using hydraulic flumes where both flow and the riverbed conditions are idealized The goal of the R3PEAT project (Remote Real-time Riprap Protection Erosion AssessmenT on large rivers) is to bridge the gap between the real-time scour hole development and flow environment through development of real-time scour monitoring system. The research focus of the project is investigation of scouring processes next to the riprap protection around bridge piers-existing structures whose stability and safety are unknown in the hydraulic environment under the influence of climate change. Research methodology combines experimental investigations on scaled physical model (Phase I) with 3D numerical model (Phase II) into hybrid modelling approach, calibrated and validated with field surveys. The research objectives of the project are: (1) develop ScourBuoy prototype (2); calibrate the physical model with field surveys; (3) improve existing empirical equations for equilibrium scour hole development using hybrid modelling
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EGU2020-1933
https://doi.org/10.5194/egusphere-egu2020-1933
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
Remote Real-time Riprap Protection Erosion AssessmenT on large
rivers
Gordon Gilja1, Antonija Cikojević2, Kristina Potočki3, Matej Varga4, and Nikola Adžaga5
1University of Zagreb, Faculty of Civil Engineering, Department of Hydroscience and Engineering, Zagreb, Croatia
(gordon.gilja@grad.unizg.hr)
2University of Zagreb, Faculty of Civil Engineering, Department of Hydroscience and Engineering, Zagreb, Croatia
(antonija.cikojevic@grad.unizg.hr)
3University of Zagreb, Faculty of Civil Engineering, Department of Hydroscience and Engineering, Zagreb, Croatia
(kristina.potocki@grad.unizg.hr)
4University of Zagreb, Faculty of Geodesy, Institute of Geomatics, Zagreb, Croatia (mvarga@geof.hr)
5University of Zagreb, Faculty of Civil Engineering, Department of Mathematics, Zagreb, Croatia
(nikola.adzaga@grad.unizg.hr)
Large number of bridges in Europe is at the end of their life span, while the frequency of
occurrence for extreme climatic events, driven by climate change, is increasing. Floods influence
morphodynamic changes in the riverbed, such as scouring of the riverbed next to the bridge
substructure, that can undermine the overall stability of the bridge. Placement of riprap protection
around bridge piers is an approach that doesn’t solve scouring problem, it rather displaces the
scour hole elsewhere in the river channel, where its location is unknown because it is formed in
the interaction between the flow and the structure, in site-specific conditions. Traditional approach
to scour monitoring is effective only if surveys are conducted during the flood conditions, while
the data acquired post-flood can underestimate the full potential of flood hazard. Detailed field
surveys of hydraulic parameters during floods are essential in the understanding of
morphodynamic evolution of the river channel, but are often scarce because they are time-
consuming and require extensive resources (e.g. the survey equipment). Therefore, the majority of
research was conducted using hydraulic flumes where both flow and the riverbed conditions are
idealized
The goal of the R3PEAT project (Remote Real-time Riprap Protection Erosion AssessmenT on large
rivers) is to bridge the gap between the real-time scour hole development and flow environment
through development of real-time scour monitoring system. The research focus of the project is
investigation of scouring processes next to the riprap protection around bridge piers - existing
structures whose stability and safety are unknown in the hydraulic environment under the
influence of climate change. Research methodology combines experimental investigations on
scaled physical model (Phase I) with 3D numerical model (Phase II) into hybrid modelling
approach, calibrated and validated with field surveys. The research objectives of the project are:
(1) develop ScourBuoy prototype (2); calibrate the physical model with field surveys; (3) improve
existing empirical equations for equilibrium scour hole development using hybrid modelling
approach; (4) investigate the dependence between turbulent flow characteristics and temporal
scour hole development and (5) investigate dependence between turbulent conditions and
incipient motion of sediment particles. The impact of the proposed project on the bridge
management systems is expected through the development of a practical remote real-time system
for erosion estimation around the riprap protection on large rivers that can be basis for the real-
time decision support system.
Acknowledgment:
This work has been supported in part by Croatian Science Foundation under the project R3PEAT
(UIP-2019-04-4046)
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... The bridge has two identical piers, 30 m high and 3.5 m wide, located in the main river channel with riprap scour protection installed around them, and abutments on high banks. This river reach was selected for analysis because it is the pilot bridge under the R3PEAT project [30], focusing on the investigation of scouring around bridge piers protected with riprap [31]. The flume bottom is lined with concrete, while the sidewalls are made of glass to allow real-time observation of the experiments. ...
Calibration and Verification of Operation Parameters for an Array of Vectrino Profilers Configured for Turbulent Flow Field Measurement around Bridge Piers—Part II
Article
Full-text available
  • Jun 2023
High-frequency velocimeters used for flow measurements during laboratory experiments allow the user to select the range for several operation parameters to set up the instrument for optimal velocity measurement. The discrepancies between velocity measurements collected with different instrument configurations can be significant, depending on the flume bed configuration and boundary conditions. The aim of this paper is to quantify the differences in flow velocity profiles measured with Acoustic Doppler Velocimeter Profilers (ADVPs) configured using a combination of profiling parameters: Ping Algorithm (PA), Transmit Pulse Size (TPS), and Cell Size (CS). Whereas in Part I of this research, the goal was to identify the optimal probe configuration for downstream measurement of the complex hydraulic structure (pier protected with riprap) based on a match of the flow rate with measurements from other instruments, in this paper, effect of distinct probe configuration on velocity profile and turbulent kinetic energy (TKE) is demonstrated. Differences between ADVPs’ configurations were analyzed through sensitivity analysis with the intention to calculate and compare any discrepancies in the velocity measurements for all the three measured velocity components: streamwise u, spanwise v and vertical w collected on two characteristic flume cross-sections. The results show that each parameter change has a significant effect on the measured values of each velocity component when compared to the Target Configuration (TC). The largest root-mean-square-error (RMSE) is observed when TPS is changed, followed by CS and PA. Absolute RMSE calculated for TPS change from 4 mm to 1 mm is, on average, 6.30 cm/s, 0.90 cm/s, and 0.82 cm/s for velocity components u, v and w, respectively. Absolute RMSE calculated for CS change from 1 mm to 4 mm is, on average, 4.49 cm/s, 0.88 cm/s, and 0.71 cm/s for velocity components u, v and w, respectively. Absolute RMSE calculated for PA change from Adaptive to Max interval is, on average, 4.04 cm/s, 0.63 cm/s, and 0.68 cm/s for velocity components u, v and w, respectively. For a change in all parameters, RMSE is greater for the cross-section downstream of the pier than for the approach cross-section: on average, 90%, 57% and 54% for a change in the PA, TPS, and CS, respectively.
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... (accessed on 9 September 2022)), a scaled model of the Drava River's reach in Croatia was used as a reference. This Drava River reach was selected because it is the location of the prototype railroad bridge selected for the investigation of scouring around bridge piers protected with riprap [42] under the R3PEAT project [43]. The prototype bridge is located in Osijek, Croatia on the Drava River 18 + 960 km (N 45.56056, E 18.70475, Figure 1). ...
Calibration and Verification of Operation Parameters for an Array of Vectrino Profilers Configured for Turbulent Flow Field Measurement around Bridge Piers—Part I
Article
Full-text available
  • Sep 2022
Flow mapping around bridge piers is crucial in estimating scour development potential under different flow conditions. The reliable measurement of turbulence and the estimation of Reynolds stress can be achieved on scaled models under controlled laboratory experiments using high-frequency Acoustic Doppler Velocimeter Profilers (ADVP) for flow measurement. The aim of this paper was to obtain operation parameters for an array of Vectrino Profilers for turbulent flow field measurement to reliably measure the flow field around bridge piers. Laboratory experiments were conducted on a scaled river model set up in an open channel hydraulic flume. Flow field data were measured on three characteristic profiles, each containing five measurement points collected by ADVPs configured as an array of two instruments. The determination of the operation parameters was done as a two-step process—calibration through the flume’s pump flow rate and verification with Acoustic Doppler Current Profiler RioGrande field data. Based on the results, the following setup for ADVPs’ operation parameters can be used to obtain reliable flow data in the scour hole next to the bridge pier: adaptive Ping Algorithm, Transmit Pulse Size of 4 mm and Cell Size of 1 mm.
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... It has been noticed that erosional processes affect downstream sections of the river due to increased flow velocities at the constricted bridge opening. The location of the final scour hole is unknown, because it is formed based on the interaction between the flow and the structure under site-specific conditions [122]. Petersen et al. [123] noticed scour of the riprap in the farther downstream area. ...
Scour at Bridge Piers Protected by the Riprap Sloping Structure: A Review
Article
Full-text available
  • Dec 2021
Bridge piers on large rivers are often protected from scouring using launchable stone, such as a riprap sloping structure. While such scour countermeasures are effective for pier protection, they significantly alter flow conditions in the bridge opening by overtopping flow and flow contraction, deflecting the formation of the scour hole downstream and exposing the downstream riverbed to additional scour. This paper provides a comprehensive and relevant review of bridge scour estimation methods for piers with a riprap sloping structure installed as a scour countermeasure. Research on empirical methods for bridge scour estimation is reviewed and analyzed with formulae used for comparable structures—complex pier formulae and formulae for river training structures. A summary of relevant formulae applicable to piers with installed scour countermeasures is provided, as well as a discussion on the possible future research directions that could contribute to the field.
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Flow Hydrodynamic in Open Channels Interaction with Natural or Man-Made Structures
Book
Full-text available
  • May 2023
Description: Streams and rivers are subject to considerable hydrodynamic loads. Flow interactions with natural or man-made structures in open channels lead to the development of complex dynamic processes, requiring further studies to comprehend fully. This Special Issue has been conceived to facilitate improvement or propose new approaches, summarize the most important findings of previous studies, and encourage the development of further knowledge in the field of open-channel flows. Various topics are addressed in this SI, including flow interaction with hydraulic structures, flow dynamics in estuaries, flow-vegetation interactions, bed sediment effects on flow structures, and the effect of channel curvature on flow behaviors and sediment transport. The studies published in this Special Issue certainly help readers understand the turbulent flow involved in open channels and apply that understanding to the design and practice of hydraulic engineering and river management.
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