Water Depth Conditions Research Articles

Wave-attenuation characteristics of combined-vegetation wave break forests for big rivers with large flood water level changes.

For large rivers with a compound cross section, the downstream channel has a very wide water surface during the flood season. A wide water surface, high water level, and larger wind speed will cause higher waves, increasing the threat of flooding to the dike. The design of a combined-vegetation wave break forest was put forward to achieve better wave attenuation effect. The main idea of this concept is to plant different types of vegetation at different locations in front of the dike. Three single-vegetation and four combined-vegetation forest schemes were tested under seven different water depth conditions. Both physical experiments and wave numerical simulations were carried out for each scheme to study the wave attenuation effect. The results showed that the wave attenuation effect of the single-vegetation wave break forest was significantly different under different water depth conditions, and the overall effect of the combined-vegetation of wave forest was better. Combined-vegetation wave break forests combine the advantages of different types of vegetation in different water levels, which makes it more economical and reasonable to plant by rivers with large water level variation. The proposed design ideas and methods could provide theoretical support for ecological revetment engineering of large rivers and insights for practical applications.

Effects of Water Immersion in Different Water Depths on Respiratory Function and Respiratory Muscle Strength among Elderly People: An Observational Study

The aim was to investigate the effect of three water levels (umbilical, 4th rib, and clavicular) on the respiratory function and respiratory muscle strength among elderly. Spirometry and respiratory strength were measured on land as baseline data. Next, water depth conditions were determined randomly, and spirometry and respiratory muscle strength were measured at each water level. The Vital Capacity and Expiratory reserve volume in the clavicular level were significantly lower than those in the land and umbilical trials. No significant difference was observed in other respiratory functions. Chest circumference and respiratory muscle strength were not significantly different among all conditions.

Time-frequency energy analysis of deepwater explosion shock wave signals based on HHT

In order to study the time-frequency characteristics of shock wave signals under deep water explosion conditions, experiments are performed using water medium explosion containers to simulate different water depth conditions, and signal analysis is performed on the shock wave data obtained in the experiments. Traditional time-frequency analysis methods such as Fourier transform and wavelet transform have many limitations on deep-water explosion shock wave signal analysis, the HHT method is used to analyse the experimental data from the three-dimensional Hilbert spectrum, marginal spectrum and instantaneous energy spectrum. The results show that the time-frequency method can effectively extract the frequency components of the deep-water explosion load signal in different periods. It provides a reference for people to understand the time frequency characteristics of shock wave signals in deep water.

Decomposition of Kemp’s ridley (Lepidochelys kempii) and green (Chelonia mydas) sea turtle carcasses and its application to backtrack modeling of beach strandings

When a sea turtle dies, it typically sinks to the bottom, begins decomposing, and floats to the surface once sufficient internal gases have accumulated to produce positive buoyancy. This process is poorly characterized and is essential to understanding where and when sea turtles found on shore may have died. We conducted decomposition studies with detailed time-temperature histories using carcasses of cold-stunned sea turtles (22 Kemp’s ridleys Lepidochelys kempii and 15 green sea turtles Chelonia mydas) at temperatures of 14-32°C and depths of 2.2-9.5 m. We found strong depth/pressure-related effects; carcasses took longer to float when incubated at greater depths than shallower depths at similar temperatures. Furthermore, carcasses incubated at colder temperatures (~15°C) took 8 times longer to float than those at 32°C at the same depth. We applied accumulated degree hours (ADH; hourly sum of ambient temperatures a carcass experienced) to characterize environmental conditions associated with different stages of decomposition and key events, including buoyancy and sinking. A formula for temperature-correction of ADH was calculated to fit a non-linear increase in decomposition at higher temperatures. These data were then used to improve an existing backtracking model by incorporating water temperature, depth (pressure), bathymetry, and postmortem condition. Heat maps of the probable mortality locations from the model agreed well with carcass and effigy drift experiments, demonstrating the overall reliability of the enhanced model. Our method can be used to estimate at-sea locations where sea turtles found washed ashore in the northern Gulf of Mexico likely died and may help inform similar efforts in other regions.

EVOLUTION OF UNSTABLE WAVE PACKETS OVER VARIABLE BATHYMETRY

Several field observations have reported the formation of rogue waves in coastal zones, see Chien et al. (2002) for an example in Taiwanese sea. The mechanisms that lead to the occurrence of rogue waves in finite water depth to shallow water are not well understood yet under the conjecture of modulation instability. Indeed, this theory for uni-directional waves shows that when kh is lower than a threshold of 1.363 in homogeneous water depth conditions, the wave train becomes stable to side-band perturbations. Then if the wave train is stable, the appearance of rogue waves is not possible within this linear stability framework. One explanation may come from the complex wave transformation mechanisms in variable bathymetry, especially, for cases of steep slopes or near the edge between a steep slope and a gentle slope as it is the case of the continental shelf. Very few laboratory experiments have been so far addressing the influence of the bathymetry on extreme wave occurrence (Baldock and Swan (1996), Kashima et al. (2012), Ma et al. (2015)).Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/a5M4PS-Lo4Q

Two-Dimensional Modelling of a Quayside Floating System

This paper studies the behaviour of a quayside floater oscillating in front of a vertical dike. In order to study the floater motion and the impact of the dike on the floater, a linear analytical model based on 2D potential flow theory in intermediate water depth conditions and a numerical model resolving 2D Navier–Stokes equations are developed. Physical tests performed for different floater dimensions in a wave tank are used as references for the analytical and numerical models. The comparison of the results obtained analytically, numerically and experimentally leads to the validity domain of the potential model. A correction of this model is proposed, based on the optimization of the radiated coefficients, and a quadratic drag term is added according to Morison equation. The impact of the different parameters of the system on floater behaviour is considered. Results show that the draft has the most important impact on floater motion.

An Experimental Study of a Bottom-Hinged Wave Energy Converter with a Reflection Wall in Regular Waves—Focusing on Behavioral Characteristics

The hybrid system of wave energy converters (WECs) using coastal structures is an attractive issue in terms of a decrease in construction costs and an improvement of the ability to capture wave energy. Most studies on the utilization of reflected waves from structures, which is one of the hybrid systems, are limited to mathematical analysis based on linear theories. Therefore, this paper presents fundamental experimental results in the presence of a reflection wall simplified as a coastal structure behind a bottom-hinged flap-type WEC under unidirectional regular waves. The behavioral characteristics and the power generation efficiency ke of the flap were investigated, focusing on wave steepness, initial water depth, and distance from the reflection wall. The results show that the condition of the initial water depth being smaller than the flap height is more effective in terms of avoiding unstable rotating of the flap. The maximum ke appeared slightly far from the node position of the standing waves because the flap shape and the power take-off (PTO) damping induce the phase difference between the reciprocating behavior of the flap and the period of the standing wave. The results imply that the optimum position of a WEC is dependent on WEC shape, PTO damping, and installation water depth.

Evaluation of the Significant Wave Height Data Quality for the Sentinel-3 Synthetic Aperture Radar Altimeter

Synthetic aperture radar (SAR) altimeters represent a new method of microwave remote sensing for ocean wave observations. The adoption of SAR technology in the azimuthal direction has the advantage of a high resolution. The Sentinel-3 altimeter is the first radar altimeter to acquire global observations in SAR mode; hence, the data quality needs to be assessed before extensively applying these data. The European Space Agency (ESA) evaluates the Sentinel-3 accuracy on a global scale but has yet to perform a detailed analysis in terms of different offshore distances and different water depths. In this paper, Sentinel-3 and Jason-2 significant wave height (SWH) data are matched in both time and space with buoy data from the United States East and West Coasts and the Central Pacific Ocean. The Sentinel-3 SWH data quality is evaluated according to different offshore distances and water depths in comparison with Jason-2 SWH data. In areas more than 50 km offshore, the Sentinel-3 SWH accuracy is generally high and less affected by the water depth and sea conditions (root-mean-square error of 0.28 m and correlation coefficient of 0.98); in areas less than 50 km offshore, the SWH data accuracy is slightly affected by water depth and sea conditions (especially the former). Compared with Jason-2, the observation ability of the Sentinel-3 altimeter in nearshore areas with water depths of 0 m-500 m is greatly improved, but in some deep water areas with stable sea conditions, the Jason-2 SWH data accuracy is higher than that of Sentinel-3. This work provides a reference for the refined application of Sentinel-3 SWH data in offshore deep water areas and nearshore shallow water areas.

Numerical investigation on the dynamic responses of three integrated concepts of offshore wind and wave energy converter

To achieve a better utilization of ocean space and energy, three integrated concepts of column-type wind turbine and heave-type wave energy converter (WEC) have been proposed for deep, intermediate and shallow water depth conditions, respectively. The WECs are installed on the wind turbine columns, then wave energy can be absorbed by power-take off (PTO) system through the relative heave motions between wind turbine column and the WEC. The spar-type floating wind turbines with long and short floaters are considered for deep and intermediate water depth conditions whereas a fixed-type wind turbine is considered for the shallow water depth condition. On the other hand, the WECs are torus-shaped heave-type devices, with dimensions and configurations the same for the three concepts. Numerical models are established for all the three concepts. The combined systems are subjected to various wind and wave conditions. The dynamic response analysis is carried out, and the responses including motions, forces and power, are compared among them. The results show that significantly different dynamic responses of the three concepts under environmental actions are observed.

Integrated continuous berth allocation and quay crane assignment and scheduling problem with time-dependent physical constraints in container terminals

This paper presents an integer programming model for integrated continuous berth allocation, quay crane assignment and quay crane scheduling problem (BACASP) in container terminals where berthing possibility depends on water depth and tide conditions. The proposed model also considers the safe distance between quay cranes and the fact that they cannot cross each other on the rails. Given the NP-Hard complexity of the proposed model, a particle swarm optimization (PSO) based meta-heuristic called the random topology particle swarm optimization algorithm (RTPSO) is developed for solving its large-size instances. To evaluate the performance of the developed RTPSO, its results are compared with the results of the exact solution and the basic PSO. The results illustrate the better performance of the proposed random topology particle swarm optimization algorithm in terms of accuracy and computational time.

Lake-depth related pattern of genetic and morphological diatom diversity in boreal Lake Bolshoe Toko, Eastern Siberia.

Large, old and heterogenous lake systems are valuable sources of biodiversity. The analysis of current spatial variability within such lakes increases our understanding of the origin and establishment of biodiversity. The environmental sensitivity and the high taxonomic richness of diatoms make them ideal organisms to investigate intra-lake variability. We investigated modern intra-lake diatom diversity in the large and old sub-arctic Lake Bolshoe Toko in Siberia. Our study uses diatom-specific metabarcoding, applying a short rbcL marker combined with next-generation sequencing and morphological identification to analyse the diatom diversity in modern sediment samples of 17 intra-lake sites. We analysed abundance-based compositional taxonomic diversity and generic phylogenetic diversity to investigate the relationship of diatom diversity changes with water depth. The two approaches show differences in taxonomic identification and alpha diversity, revealing a generally higher diversity with the genetic approach. With respect to beta diversity and ordination analyses, both approaches result in similar patterns. Water depth or related lake environmental conditions are significant factors influencing intra-lake diatom patterns, showing many significant negative correlations between alpha and beta diversity and water depth. Further, one near-shore and two lagoon lake sites characterized by low (0-10m) and medium (10-30m) water depth are unusual with unique taxonomic compositions. At deeper (>30m) water sites we identified strongest phylogenetic clustering in Aulacoseira, but generally much less in Staurosira, which supports that water depth is a strong environmental filter on the Aulacoseira communities. Our study demonstrates the utility of combining analyses of genetic and morphological as well as phylogenetic diversity to decipher compositional and generic phylogenetic patterns, which are relevant in understanding intra-lake heterogeneity as a source of biodiversity in the sub-arctic glacial Lake Bolshoe Toko.

Damage Mode of Long Tube Structure at Different Water Depths under Strong Impact

In order to study the damage mode of the structure under strong impact, the finite element analysis software ABAQUS acoustic-coupling method is used to calculate and analyze the strong impact of the long tube structure under different water depths and different impact factors. The study obtained damage patterns influenced by impact factors and water depth conditions. It provides a reference for the calculation and impact design of underwater structures under strong impact.

DISTRIBUTION AND DENSITY OF DEMERSAL FISHES IN YOUTEFA BAY, PAPUA, INDONESIA: A STUDY USING HYDROACOUSTIC TECHNOLOGY

A study was conducted to estimate the distribution and density of demersal fish in Youtefa Bay, Papua, Indonesia, using hydroacoustic technology. The hydroacoustic survey was carried out using a single beam echosounder SIMRAD EK-15 which operates at a frequency of 200 kHz. The hydroacoustic data was processed using Echoview software with a threshold between -70.00 to -34.00 dB. Schooling fish were detected at a maximum distance of 3 m from the seabed, with average volume backscattering strength ranging between -60.13 and -42.01 dB. The demersal fish density in the Youtefa Bay ranged from 0.09 to 42.19 fish m-3 with an average density of 12.62 fish m-3. The schools of demersal fish were dominantly detected in the coastal waters of Enggros Village to Abe Pantai Village. The condition of substrate and water depth seems to influence the spatial and vertical distribution of demersal fish in the Youtefa Bay.

Development of High Yielding Deep Water Rice Variety BRRI dhan91 for Semi Deep Flooded Ecosystem of Bangladesh

Deep water rice ecosystem represents the flood-prone rice ecosystem where rice plant requires elongation ability to reach the surface with a certain amount of plant height to withstand in stagnant flood water condition. Low yield potentiality of locally adapted deep water cultivars limits the total rice production in the country. In present study, efforts were made to evaluate the suitability and adaptability of newly developed high yielding deep water breeding line BR10230-15-27-7B and control variety Fulkori under semi deep water ecosystem of farmer’s field condition in three consecutive years. At six locations, water depth varied from 60 to 140 cm under semi deep water ecosystem. In 2016 and 2017, mean yield of the line ranged between 2.9 to 3.1 t ha-1 while 1.7 t ha-1 for the local control variety Fulkori. However, around 1.0 t/ha yield advantage was found for the newly developed breeding line. Thus, the higher yield potentiality of the breeding line under 140 cm water depth conditions suggested its suitability under shallow flooded environments. During final evaluation in 2018, larger variation was observed in terms of grain yield ranging from 1.1 to 3.8 t ha-1 for the line while 0.4 to 1.7 t ha-1 for the control variety when evaluated under actual deep water areas. This result also supported that this line have greater potentiality under shallow flooded condition. In addition, the breeding line exhibited similar plant height with at least six days earliness compared to the control variety. Finally, National Seed Board (NSB) approved this line as variety and designated as BRRI dhan91 for broadcast Aman (B. Aman) season. In future, this new rice variety could help the local rice growers to cultivate modern high yielding rice variety in shallow flooded environments. BRRI dhan91 also showed better performance for tallness with lodging tolerance, submergence tolerance and moderate elongation ability under shallow flooded conditions.
 Bangladesh Rice j. 2019, 23(1): 57-63

Stromatolite framework builders: ecosystems in a Cryogenian interglacial reef

A convergence of climate, paleolatitude, basin evolution, water depth and seawater chemistry conditions, favourable for carbonate precipitation and preservation, facilitated initiation and sustained growth of the ∼350 m-thick Arkaroola carbonate reef, part of the Balcanoona Formation, during the Cryogenian interglacial in South Australia’s northern Flinders region. The reef is distinguished by its diverse stromatolitic framework; its internal architecture as exposed on the gorge walls of Kingsmill Creek, reveals spatial and temporal variability of the stromatolite assemblage. Growth of planar microbial biostromes initiated development of a stable carbonate substrate on underlying thick mudstone-to-sandstone. Once stabilised, a robust reef framework developed, first through vertical growth of large domical thrombolitic stromatolites forming stacked bioherms of metre-scale relief. Biological modification of the local environment through substrate stabilisation, wave-energy baffling and aggradationally driven shallowing then enabled an ecological succession of stromatolite forms from microbial biostrome colonisation through to a climax community of domal, columnar and branching stromatolites. The spatial and stratigraphic distribution of stromatolite forms along with allochthonous facies, including intraclastic, peloidal and oolitic grainstone and packstone, characterises development of a windward forereef, reef crest, reef flat and leeward back-reef lagoon. Variability of stromatolite forms across the reef structure indicates ecological adaptation of function and form to niche conditions. Microbial (stromatolite) growth in a range of forms overwhelmingly controlled carbonate production in the Arkaroola reef. The range of stromatolite forms and their facies distribution within the reef is consistent with biological control on ecosystem development and stabilisation analogous to those of Phanerozoic and modern reef ecosystems. The Arkaroola reef exhibits a comparable ecological succession within the evolutionary realm of cyanobacteria in the late Proterozoic. Furthermore, the Arkaroola reef records relative climatic and sea-level stability within the Cryogenian Period, notable for severe climatic upheaval.

Numerical and Experimental Investigation of Wave Overtopping of Barriers

We present a study of wave overtopping of barriers. The phenomenon of the wave overtopping over emerged structures is reproduced both numerically and experimentally. The numerical simulations are carried out by a numerical scheme for three-dimensional free-surface flows, which is based on the solution of the Navier–Stokes equations in a novel integral form on a time-dependent coordinate system. In the adopted numerical scheme, a novel wet–dry technique, based on the exact solution of the Riemann problem over the dry bed, is proposed. The experimental tests are carried out by adopting a nonintrusive and continuous-in-space image-analysis technique, which is able to properly identify the free surface even in very shallow waters or breaking waves. A comparison between numerical and experimental results, for several wave and water-depth conditions, is shown.

Combination of LS-SVM algorithm and JC method for fragility analysis of deep-water high piers subjected to near-field ground motions

The objective of this paper is to propose a novel fragility analysis method pertinent to the combination of the least squares support vector machine (LS-SVM) algorithm and JC method for the vulnerability estimation of deep-water high piers located in reservoirs under near-field ground motions. First, the uncertainties associated with the design parameters are considered and the LS-SVM algorithm is adopted to predict the cross-sectional critical curvature values of each damage state of the example pier and determine the probability distributions. Then, a group of finite element models of the example pier is developed using the OpenSees platform for considering the uncertainties related to the design parameters and near-field seismic waves; the Morrison equation is employed to calculate the added mass to simulate the hydrodynamic pressure. Meanwhile, the dynamical responses of the example pier with seven different water depth conditions are investigated using increment dynamic nonlinear analysis along the longitudinal and transverse directions under seismic excitations. Finally, the fragility functions are derived based on the JC method to consider the probability distributions of the cross-sectional critical curvature values and dynamical responses simultaneously; these functions are applied for assessing the damage probability at different damage states of the example pier. It can be concluded that the hydrodynamic pressure plays an important role in influencing the natural vibration period and mode shape of the deep-water high pier. In the slight, moderate, and extensive damage states, the damage probability of the middle-upper and bottom areas of the example pier is relatively large under longitudinal near-field seismic excitation; nevertheless, only the bottom is easily damaged under transverse near-field seismic excitation.

On the stability of rock armored rubble mound structures

Estimation of the required armor size is a major task in the design of coastal structures under wave loading such as breakwaters and revetments. Several semi-empirical formulas have been developed for this purpose. However, these formulas are often either limited to certain water depth conditions or do not incorporate the permeability of the structure in an appropriate way. The main objectives of this study are to (a) develop a unified physically sound formula for the estimation of the required rock size in all relevant water depth conditions and (b) to relate the effects of the permeability of the structure directly to physical parameters. To achieve these, first a comprehensive data base of deep and shallow water experiments within the design conditions was built. Then physical reasoning along with a robust data mining approach, i.e. M5 model tree, were used to develop formulas for armor stability. In the stability formula, wave characteristics such as the significant wave height and spectral energy mean period (Tm-1,0) are invoked while the permeability is incorporated using the ratio between the size of the core material and the armor stones. Accuracy metrics such as discrepancy ratio and scatter index indicated high performance of the model in different conditions. Finally, a probabilistic formula and some guidelines are provided for practicing engineers.

Herpetofauna Occupancy and Community Composition along a Tidal Swamp Salinity Gradient

Occupancy patterns of herpetofauna in most tidal freshwater swamps are unknown. Tidal freshwater swamps currently face multiple threats, including salinization, which can influence their associated plant and animal communities. The impacts of salinization to herpetofauna communities in tidal freshwater swamps have not been assessed. To improve predictions regarding these herpetofauna, we conducted surveys in tidal freshwater swamps of the Savannah National Wildlife Refuge located in South Carolina, USA, from March to June, 2016 and 2017, using a variety of methods. Goals included inventorying species, determining communities, examining microhabitat associations, and modeling occupancy to predict the impacts of salinity changes. We detected 8 species of amphibians and 12 species of reptiles in our surveys. Community analyses failed to detect patterns related to measured environmental variables. Species richness and diversity declined along the salinity gradient, but the observed patterns did not match our predictions and may instead be related to site-level heterogeneity. Microhabitat associations were detected for two amphibian species via occupancy analyses. Occupancy and regression analyses indicated soil salinity may be a factor affecting nine species’ occurrences. Amphibian detections may be affected by water depth, pH values, and weather conditions. These results expand our understanding of herpetofauna within an understudied, and threatened, wetland type.

Energy Dissipation in Solid Roller Bucket and Controlled Stilling Basin for Ogee Stepped Spillway

Hydraulic jump type II stilling basin is generally preferred as an energy dissipator for ogee spillway but it is uneconomical due to longer structure. On the other hand, roller bucket uses relatively shorter structure over a sloping apron or horizontal stilling basin. In this study, an attempt has been made to evaluate the performance of an ogee profile stepped spillway in combination with solid roller bucket and stilling basin type II for energy dissipation. Laboratory experiments are performed on a physical working model of ogee profile stepped spillway at discharge ranging from 0.0032 to 0.0069 m3/s for a head of 1.5m, 4m & 7m and the results compared for energy dissipation (non-dimensional parameter (yc / h) = 0.69). The model results show that stepped spillway model without v-notch achieves 92.40 % energy dissipation. Thus this model is found to be more suitable to acquire the ideal condition of sequent depth and tail water depth in stilling basin for all the discharges.