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Accurate suspended sediment concentration measurements are key to understand and quantify the sediment transport patterns in the surf and swash zones. One of the most widely used instruments to collect suspended sediment concentrations is the Optical Backscatter Sensor (OBS). However, the OBS is known to give erroneous readings when deployed in bubbly environments like the surf zone. The present study aims to quantify the influence of an aerated wave breaking environment on the OBS sediment concentration measurements. Experiments are performed in a large wave flume, which ensures full air entrapment under plunging breaking waves, and avoids scale effects that could affect the volume of entrapped air, the air bubble penetration depth and the residence time of air bubbles in the post-breaking turbulent eddies. OBS measurements are obtained at 66 locations along a fixed bed profile for 14 regular breaking wave conditions. In the absence of suspended sediment particles, OBS voltage measurements are used as a proxy for air bubble content. The presented OBS results show peaks up to 1.49 V (31% of the OBS measurement range, corresponding to 16 g/l for sediment with d50 = 0.25 mm) produced by air bubbles in the most energetic tested wave breaking conditions, while the maximum time-averaged value obtained is 0.48 V (10% of the OBS measurement range, corresponding to 5 g/l). The results highlight the importance of considering the presence of air bubbles where OBS are deployed to measure suspended sediment concentrations. A good correlation is found between the breaker depth index and the air bubble distribution and two predictive formulas are derived to forecast the area of air bubble influence in the surf zone. We offer our gratitude to the CIEM staff, especially to Joaquim Sospedra for his endurance and leadership. The work described in this paper was supported by the European Community’s Horizon 2020 Programme by means of the Hydralab+ Project (contract number 654110). This paper contributes to the Hydralab+ legacy together with a set of coordinated papers in other journals. Finally we acknowledge the economical funding and support received by the Secretaria d´Universitats i Recerca del Dpt. d´Economia i Coneixement de la Generalitat de Catalunya (Ref. 2017SGR00773).

Large-Scale Particle Image Velocimetry (LSPIV) is an extension of a quantitative imaging technique to measure water surface velocities using simple and inexpensive equipment. This paper describes the implementation of imaged-based LSPIV in eight different environmental flow and hydraulic engineering applications for the investigation of complex configurations with and without sediment transport (bed and suspended loads). These applications include the investigation of sedimentation in shallow reservoirs, run-of-river hydropower plants, side weirs used to control bank overflow, flow fields in different spillway configurations with and without Piano Key Weir (PKW), oil spills with flexible and rigid barriers, groin fields, river confluence, and sediment flushing in reservoirs. The paper summarises some special problems encountered in such study cases. The selection and adjustments of the parameters to solve them properly were examined. The potential of LSPIV to measure surface flow velocities in the context of river and dam engineering projects is shown. Despite significant variations of natural and artificial illuminations and seeding tracers in the laboratory, field, wind, and water surface elevation, LSPIV was applied successfully to obtain velocity measurements. LSPIV has proven to be a reliable, flexible, and inexpensive flow diagnostic tool that can be employed successfully in many engineering applications.

Rainfall runoff collection in ephemeral streams is an objective in semi-arid zones. Rack intake systems are proposed to collect these flash floods with intensive sediment transport. The design parameters address the problem of clogging the spacing between bars. Experiments for two different void ratio racks are shown. Flows, longitudinal slopes in the rack, and water with three gravel-sized sediments were tested. Results such as effective void ratio due to the gravel deposition over the rack, the evolution of the flow rejected during each test, and the quantification of materials collected and deposited, are presented. The optimal longitudinal rack slope seems to be close to 30%. The effective void ratio is related to several hydraulic parameters calculated at the beginning of the rack. Some adjustments were proposed to predict the effective void ratio.

Source: https://erdc-library.erdc.dren.mil/jspui/ This report provides information and data documenting a coastal processes project called the SUPERTANK Data Collection Project performed at the O. H. Hinsdale Wave Research Laboratory, Oregon State University, over the period 29 July to 20 September 1991. The objectives of the project were to (a) collect data to verify and improve existing macro-scale beach profile change numerical simulation models, (b) collect data to develop advanced hydrodynamic, cross-shore sand transport, and meso-scale beach profile change numerical simulation models, (c) collect data to quantify performance of sandbars constructed offshore as a beneficial use of dredged material, (d) test and compare sediment-sensing acoustic instruments in a controlled, field-scale environment in support of dredging research, and (e) collect data to improve understanding of micro-scale fluid and sand motion. SUPERTANK was conducted as a multidisciplinary and multi-institutional cooperative effort in which the investigators shared instrumentation and expertise. NOTE: This file is large. Allow your browser several minutes to download the file.

Source: https://erdc-library.erdc.dren.mil/jspui/ This report provides information and data documenting a coastal processes project called the SUPERTANK Data Collection Project performed at the O.H. Hinsdale Wave Research Laboratory, Oregon State University, over the period 29 July to 20 September 1991. The objectives of the project were to (a) collect data to verify and improve existing macro-scale beach profile change numerical simulation models, (b) collect data to develop advanced hydrodynamic, cross-shore sand transport, and meso-scale beach profile change numerical simulation models, (c) collect data to quantify performance of sandbars constructed offshore as a beneficial use of dredged material, (d) test and compare sediment-sensing acoustic instruments in a controllred, field-scale environment in support of dredging research, and (e) collect data to improve understanding of micro-scale fluid and sand motion. SUPERTANK was conducted as a multidisciplinary and multi-institutional cooperative effort in which the investigators shared instrumentation and expertise. NOTE: This file is large. Allow your browser several minutes to download the file.