Acoustic reflection measurements of seabed elevation were made at Stanhope Beach, Prince Edward Island, during three successive storms in October-November 1989. The instruments were located approximately 200 m offshore on the seaward face of a shore parallel bar in a mean water depth of 2.2 m. Bed elevation measurements were made at 30-min intervals with a range resolution of -+ 1 mm at horizontal spacings between 22 cm and 1.5 m, using an array of four acoustic sounders operating at 1, 2.25, and 5 MHz. It is shown that such an array can be used as (1) an interferometer to determine bedform properties and migration rates, (2) a leveling device to determine changes in local bottom slope, and (3) an erosion/deposition gauge. In the interferometric mode, time domain autocorrelation and cross-correlation analyses of the bottom elevations are used to estimate the wavelengths, migration rates, and migration directions of sand ripples and megaripples. The ripple wavelengths (10-15 cm) and heights (3-5 cm) are comparable to measurements made by divers. Ripple migration rates were 1-6 cm h -1 directed offshore in the direction of the mean shore normal near-bottom current and increased with increasing mean current speed. Evidence of megaripple-like features (2-5 cm height; 1.5-3 m length) is found, also migrating in the direction of the mean shore normal near-bottom drift, at speeds of about 20 cm h -1 . Bedload transport rates in the onshoreoffshore direction are estimated from the bedform migration rates. The ripple transport rate was small (an order of magnitude smaller than the transport of sediments in suspension by the mean offshore drift). In contrast, the large-scale bedform transport appears to have been comparable to the mean current transport of suspended sediment. Interestingly, it appears that the total bedform transport was comparable to that predicted by Watanabe's (1981) net bedload transport formula, provided a coefficient appropriate to irregular wave conditions is used. During the third and highest-energy storm event, the measurements indicate transition to flat bed, and generalized local erosion at a maximum rate of 8 cm h -1 . This erosion event was associated with a general shoreward migration of the bar.

Acoustic measurements of spatially-correlated depth changes in the nearshore zone during autumn storms

Laboratory investigation of coastal beach erosion processes under storm waves of slowly varying height

Amos, C.L.; Kassem, H.; Townend, I.; Umgiesser, G.; Madricardo, F.; Zaggia, L.; Manfe, G.; Lorenzetti, G., and Gomez, E., 2020. Using historical data to examine the accuracy of sand transport field measurements in two nearshore marine settings. Journal of Coastal Research, 36(5), 1013–1028. Coconut Creek (Florida), ISSN 0749-0208.A re-analysis of historical data from two field campaigns was undertaken to examine the accuracy of measurements of bed load (Qb) and total transport (Qtot) of sand in (1) a wave-dominant shoreface off western Newfoundland, Canada, and (2) a tide-dominant inlet of Venice Lagoon, Italy. Video tapes recorded within Sea Carousel (a benthic annular flume) deployed off Newfoundland were used to determine the transport of medium to coarse sand under controlled unidirectional flow conditions. These results were compared with Helley-Smith sand trap measurements of bed load of fine to medium sand in a tidal inlet of Venice Lagoon, Italy. Ripple migration rates in Sea Carousel were similar to those measured in rivers and shallow marine settings at similar flows. Accuracy of sand transport rate (derived from ripple motion) was assessed by comparison to fundamental methods presented in the literature. Some of the scatter in correlations with earlier methods was removed by using a nondimensional form of total sand transport and correlating it to excess stream power (i.e. above a traction threshold). Better correlations were found between immersed (bed load) transport rate and excess stream power by applying a published adjustment to the observations for flow depth and grain diameter. Total immersed (normalized) sand transport () in Sea Carousel correlated with excess stream power in a fashion similar to results reported in the literature: = 0.288(ω – ωcr)1.65 kg m–1 s–1, where the immersed total sand transport is normalized with respect to flow depth and grain diameter. The sand trap data also followed this fit in part (2006 data only) but demonstrated greater scatter. The data herein thus fell in line with those reported in the literature from a wide variety of flume and field settings and for a wide variety of grain sizes. It is concluded that annular benthic flumes offer a reasonable and reliable method of assessing sand transport under controlled conditions of flow. The results from Sea Carousel and the Helley-Smith traps appear to follow the same relationships and so appear compatible. However, benthic sand traps show a higher degree of scatter, perhaps due to the uncertainties in how they sit on the seabed, and due to the arbitrary conditions of flow to which they are subjected when deployed.

Using Historical Data to Examine the Accuracy of Sand Transport Field Measurements in Two Nearshore Marine Settings

The invention discloses a physical experiment system and method for tidal creek side wall erosion, and belongs to the technical field of measurement of research for bulkhead wall collapse mechanism ofa tidal flat-tidal creek system. The experiment system comprises a tidal creek side wall shaping area, a water circulation system, a water level and flow velocity measurement and control system, a seepage control system, a porewater pressure and soil moisture content monitoring system and a bulkhead wall damage monitoring system. According to the system and the method, the slow erosion process ofthe tidal creek side wall under the joint action of tide and seepage can be simulated, then an instantaneous collapse process under the gravity action is simulated, the collapse type of the tidal creek wall is judged, and the damaged area is determined.

Physical experiment system and method for tidal creek side wall erosion

The invention discloses a method for artificial sand beach, sand filling and maintenance engineering construction. The method comprises the following steps: energy distribution change of an original engineering sea area; motion analysis on the transport of a sediment plane in the engineering sea area; analysis on the motion of sediments on a transverse profile of an artificial sand beach as well as an equilibrium state of the motion; research on engineering structure height and stability; artificial sand beach, sand filling and maintenance construction processes; standardization of mud wave parameters of the artificial sand beach. According to the method disclosed by the invention, a hydrodynamic pattern in which the artificial sand beach or artificial sand filling can stably exist for a longer term is favorably found; not only is the sand filling necessity favorably determined, but also a proper sand filling scheme is favorably provided, and a guidance for design scheme adjustment is provided; rational design revision suggestions are made, and a maintenance scheme is provided; through the artificial sand beach, sand filling and maintenance construction processes, suggestions are made on the processes of all engineering methods and structures in the actual construction, so that a help is provided for successful engineering implementation; getting recommendations and reference standards on mud critical wave parameters of the artificial sand beach mud are given to facilitate the avoidance of the mud situation of the artificial sand beach.

Method for artificial sand beach, sand filling and maintenance engineering construction

The invention provides a coastal engineering silt physical model test bottom bed dynamic and comprehensive observation method. The method is characterized in that the method is involved in a total station, high-speed cameras, a mini-type soil pressure sensor and pore water pressure sensors, wherein the total station and the high-speed cameras are arranged on the outer side of a silt physical model test water tank and the mini-type soil pressure sensor and the pore water pressure sensors are arranged in a bottom bed in the silt physical model test water tank; the observation method includes a high-speed photographing method, a double-sensor synchronous point detection method and a total station section measurement method, the high-speed photographing method is used for photographing the bottom bed dynamic evolution and the wave time interval change from the glass side wall of the silt physical model test water tank, the double-sensor synchronous point detection method is used for separating dynamic pressure generated from waves through the pore water pressure sensors so as to acquire the actual change of the elevation of the bottom bed, the total station section measurement method includes the steps that after waves are generated and water is drained out slowly, the section is scanned in a scattered mode through the total station, so that final terrain is acquired and corrected. The method is suitable for being used in a water tank test and the dynamic evolution of the whole physical model test bottom bed is synchronously observed in real time.

Coastal engineering silt physical model test bottom bed dynamic and comprehensive observation method

An experiment was conducted in a wave flume to examine the processes of sandy beach profile evolution under regular waves. The impacts of various wave conditions on quartz sand were discussed. Every case was initiated with one constant slope. Beach profile evolution was measured by remote video camera technique and bathymetry data collected from the laser total station was used to calibration. The results of a number of cases were discussed and video technique performed well in monitoring time series beach profile evolution.

Experimental Studies on Sandy Beach Profile Evolution in 2D Wave Flume

Yang, Z.T.; Li, H.J.; Liang, B.C.; Lee, D.Y.; Pan, X.Y., and Xu, Y., 2016. Laboratory experiment on the bed load sediment transport over rippled bed. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 497–501. Coconut Creek (Florida), ISSN 0749-0208. Bed load sediment transport over rippled bedforms was investigated through a series of laboratory experiments with different combinations of bed slope, grain size, wave conditions and water level using a 2D wave flume. In addition to the measurement of surface waves and velocity, the water surface and bottom bed elevation were precisely monitored using video cameras to record the continuous processes of profile evolution, including ripple formation and migration under the assumption of longshore uniformity. The bed load sediment transport flux associated with ripple migration was then estimated....

https://bioone.org/journals/journal-of-coastal-research/volume-75/issue-sp1/SI75-100.1/Laboratory-Experiment-on-the-Bed-Load-Sediment-Transport-over-a/10.2112/SI75-100.1.pdf

Zhengtong Yang

Papers

Coastal engineering silt physical model test bottom bed dynamic and comprehensive observation method

Experimental Studies on Sandy Beach Profile Evolution in 2D Wave Flume

Laboratory Experiment on the Bed Load Sediment Transport over a Rippled Bed