ScourBuoy – concept for scour monitoring system

<p>The objective of this paper is to present the ScourBuoy – concept for scour monitoring system. The ScourBuoy prototype is currently under development within the R3PEAT project (Remote Real-time Riprap Protection Erosion AssessmenT on large rivers), which aims to investigate scouring processes next to the riprap protection around bridge piers. ScourBuoy integrates commercially available technical devices into a functional system for scour monitoring during flood conditions. Sensors used are single beam echo sounder that collects depth and temperature data, multi-GNSS device for 3D positioning, compass for orientation respective to the True North and motion sensor for pitch and roll data. Combined output from the sensors allows user to calculate river depth and monitoring of scour development during floods. Advantage of ScourBuoy is adaptability to the field conditions, such as placement over the scour hole, as well as simpler deployment and reallocation in comparison to fix-mount solutions. ScourBuoy prototype was built using a common small-scale pipe float with an 80 mm inner diameter hole, which was used as a holder for an aluminium pipe. Aluminium pipe is used as a casing for echo sounder, positioned as downward-looking, so it stays submerged during deployment. The rest of the sensors are enclosed in the waterproof housing placed atop of the buoy, permanently above the waterline. The ScourBuoy will be a practical and affordable system which will allow researchers and engineers to collect measurements for scouring estimation. It will be used as a support system for rapid and timely decision making. Finally, developed Scour Buoy will present an alternative for real-time scour monitoring which allows responsive adapting to the specific conditions at the locations affected by scour.</p>

Remote Real-time Riprap Protection Erosion AssessmenT on large rivers

<p>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 </p><p>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.</p><p><strong>Acknowledgment:</strong><br>This work has been supported in part by Croatian Science Foundation under the project R3PEAT (UIP-2019-04-4046)</p>