The highly dynamical entrainment and transport processes of solids due to geophysical flows is a major challenge studied by water infrastructure engineers and geoscientists alike. A miniaturised instrumented particle that can provide a direct, non-intrusive, low-cost and accessible method compared to traditional approaches for the assessment of coarse sediment particle entrainment is developed, calibrated and tested. The instrumented particle presented here is fitted with inertial microelectromechanical sensors (MEMSs), such as a triaxial accelerometer, a magnetometer and angular displacement sensors, which enable the recording of the particle’s three-dimensional displacement. The sensor logs nine-axis data at a configurable rate of 200–1000 Hz and has a standard mode of deployment time of at least one hour. The data can be obtained and safely stored in an internal memory unit and are downloadable to a PC in an accessible manner and in a usable human-readable state. A plethora of improved design specifications have been implemented herein, including increased frequency, range and resolution of acceleration and gyroscopic sensing. Improvements in terms of power consumption, in comparison to previous designs, ensure longer periods of data logging. The embedded sensors are calibrated using simple physical motions to validate their operation. The uncertainties in the experiments and the sensors’ readings are quantified and an appropriate filter is used for inertial sensor fusion and noise reduction. The instrumented particle is tested under well-controlled lab conditions, where the beginning of the destabilisation of a bed surface in an open channel flow, is showcased. This is demonstrative of the potential that specifically designed and appropriately calibrated instrumented particles have in assessing the initiation and occurrence of water infrastructure hazards.

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Obtaining a better understanding of the underlying dynamics of the interaction of turbulent flows and the bed surface that contains them, leading to the transport of coarse particles in fluvial, coastal, and aeolian environments, is considered as one of the fundamental objectives and the most complex problems in Earth surface dynamics and engineering. Recent technological advancements have made it possible to

Acoustic Doppler velocimetry profilers (ADVPs) are widely used in both experimental and field studies because of their robustness in velocity measurements. The acquired measurements do not only offer estimates of the local and instantaneous flow velocity at the interrogated measurement volume, but can also be further processed for the estimation of the bed surface shear stresses, thus they are finding a wide range of applications ranging from water engineering to geomorphology and eco-hydraulics. This study aims to evaluate the performance of an ADVP in obtaining hydrodynamics measurements under fixed flow conditions, with various probe configurations. To this goal, a robust search is conducted where ADVP probe settings are sequentially altered. A number of assessment criteria are used including qualitative observations, such as checking the shape of the velocity profile, as well as quantitative error metrics, including signal-to-noise ratio, correlations and number of spikes. Further, estimation of the bed shear stresses computed by means of using the log Law of the Wall and turbulent kinetic energy, allow obtaining a better understanding of the uncertainties involved and the importance of making a better informed choice with respect to the probe configuration settings. Thus, the methodology and performance metrics provided herein, although presented for a given flow, can generally be applied from practitioners and researchers alike.

<p>One of the most vulnerable elements of the built environment is critical infrastructure constructed near water bodies, as flowing water negatively impacts their performance [1]. Water-related hazards can increase degradation effects which can be the leading cause for their structural failure. The current practice to assess the condition of structures is typically based on visual inspections, which in many cases are carried out in challenging environmental conditions posing threats for the health and safety of inspectors, among other issues [2]. Important key points about the safety of the structures are often not captured by the visual inspections because these areas of interest are not accessible or visible by inspectors. Real-time monitoring of flood events together with other environmental and structural-related datasets are considered key to better understanding essential aspects of degradation effects at infrastructure. The difficulty in detecting seepage processes inside the body of geo-infrastructure with conventional methods also leads to irreversible impacts with significant disruption and costs to road asset owners, maintainers, and users. The need to obtain real-time information about the evolution of natural and climatic hazards is therefore considered necessary considering the ageing infrastructure, constructed near geomorphologically active rivers, and the extreme shifting climatic conditions.</p><p>This work investigated the development of a new risk-monitoring ecosystem to remotely assess the condition of infrastructure. The development of two sensing units with complementary characteristics to provide information about flood risk at bridge sites and seepage processes at road embankments is presented. The sensing system is based on a cloud-based interface with a web-based visualization tool that enables asset owners to monitor in real-time the health of infrastructure systems and receive early warnings when incoming data exceed predetermined threshold levels [1,2,3]. Finally, the potential application location of the sensing units is also discussed alongside the proposed threshold levels that will provide information about the low, medium, high, and very high-risk probability.</p><p><strong>References</strong></p><p>[1] Michalis, P., Saafi, M. and Judd, M. 2012. Wireless sensor networks for surveillance and monitoring of bridge scour. Proceedings of the XI International Conference Protection and Restoration of the Environment - PRE XI. Thessaloniki, Greece, pp. 1345–1354.</p><p>[2] Michalis, P. Xu., Y. and Valyrakis M. (2020). Current practices and future directions of monitoring systems for the assessment of geomorphological conditions at bridge infrastructure. River Flow 2020. Proceedings of the 10th Conference on Fluvial Hydraulics, Delft, Netherlands, 7-10 July. pp. 1-6.</p><p>[3] AlObaidi, K. and Valyrakis, M. (2021). Explicit linking the probability of entrainment to the flow hydrodynamics, Earth Surface Processes and Landforms, DOI: 10.1002/esp.5188.</p>