Measured Water Depth Research Articles

Design, Implementation and Navigation Test of Manta-type Unmanned Underwater Vehicle

This paper describes the mathematical modeling, control algorithm, system design, hardware implementation and experimental test of a Manta-type Unmanned Underwater Vehicle (MUUV). The vehicle has one thruster for longitudinal propulsion, one rudder for heading angle control and two elevators for depth control. It is equipped with a pressure sensor for measuring water depth and Doppler Velocity Log for measuring position and angle. The vehicle is controlled by an on-board PC, which runs with the Windows XP operating system. The dynamic model of 6DOF is derived including the hydrodynamic forces and moments acting on the vehicle, while the hydrodynamic coefficients related to the forces and moments are obtained from experiments or estimated numerically. We also utilized the values obtained from PMM (Planar Motion Mechanism) tests found in the previous publications for numerical simulations. Various controllers such as PID, Sliding mode, Fuzzy and H∞ are designed for depth and heading angle control in order to compare the performance of each controller based on simulation. In addition, experimental tests are carried out in a towing tank for depth keeping and heading angle tracking.

Study on Stability of Underwater Trench of Immersed Tunnel of Hongkong-Zhuhai-Macau Bridge

The studies carried out to appropriate slope ratio for underwater trench of immersed tunnel of Hongkong-Zhuhai-Macau Bridge. A test trench of 100-meter-long and 21-meter-width was excavated under Lingding Ocean along designed axis of immersed tunnel. The trench includes four slope ratio, such as 1:5, 1:6, 1:8 and 1:10. Two actual measurement which includes multibeam measurement and single beam double frequency measurement were used to measure water depth and section form in different time. It is recommended that slope ratio 1:6 can be adopted for underwater trench of immersed tunnel of HZM Bridge.

The use of CFD modelling to optimise measurement of overflow rates in a downstream-controlled dual-overflow structure

The measurement of the flow through complex combined sewer overflow structures in the frame of automated monitoring remains difficult. In this paper, a methodology based on the use of computational fluid dynamics (CFD) modelling in order to improve the instrumentation of a downstream-controlled dual-overflow structure is presented. The dual-overflow structure is composed of two combined sewer overflows (CSOs) connected by a rectangular channel and controlled by a downstream gate located at the entry of the Meyzieu waste water treatment plant (close to Lyon, France). The analysis of the CFD results provides: (i) a better understanding of the interaction between the two CSOs--that means the hydraulic operation, the hydrodynamic behaviour, the backflow effect--and (ii) an ability to optimise the location of the water depth sensor. The measured water depth is used to assess the overflow rate by means of a numerical relationship. Uncertainties are also assessed.

An evaluation of the influence of water depth and river inflow on quantitative Cladocera-based temperature and lake level inferences in a shallow boreal lake

Hydrological parameters can potentially have an overwhelming influence on sedimentary assemblages of Cladocera at certain sampling sites that can cause problems for palaeoenvironmental reconstructions. We applied a previously developed Cladocera-based inference model of water depth and a mean July air temperature transfer function developed in this study to a surface sediment dataset of fossil Cladocera from a lake in eastern Finland aiming to investigate the influence of stream flow and water depth on reconstruction results. The developed temperature-inference model, using the weighted averaging-partial least squares technique, had relatively favourable performance statistics suggesting that it is valid in means of performing temperature estimations. When the temperature model was applied to the intralake samples, the lotic samples had inferred values mostly within the model’s prediction error and only one lotic sample showed an underestimated temperature. Samples taken from depths over ~3 m inferred generally underestimated temperatures, although most of the values were within the model’s prediction error. The water depth reconstructions correlated significantly with the measured water depth, but the shallowest samples and most of the lotic samples yielded overestimated inferred values and the samples taken from depths >5 m showed underestimated values. In both reconstruction sets, the inferred values were underestimated in samples taken from deeper sites. Based on the present results, it may be recommendable that downcore sediment samples should be taken from intermediate depths, where also the diversity is higher, and deepest sites and inflows should be avoided. However, more research is needed to validate these results in a larger geographical context.

Statistical Combination of Spatial Interpolation and Multispectral Remote Sensing for Shallow Water Bathymetry

There is often a need for making a high-resolution or a complete bathymetric map based on sparse point measurements of water depth. Well-known feasible methods for this problem include spatial interpolation and passive remote sensing using readily available multispectral imagery, whose accuracies depend strongly on geometric and optical conditions, respectively. For a more accurate and robust water-depth mapping, in this letter, the two methods are combined into a new method in a statistically reasonable and beneficial manner. The new method is based on a semiparametric regression model that consists of a parametric imagery-based term and a nonparametric spatial interpolation term that complement one another. An accuracy comparison in a test site shows that the new method is more accurate than either of the existing methods when sufficient training data are available and far more accurate than the spatial interpolation method when the training data are scarce.

Validation of a method for determining the depth of glacial melt ponds using satellite imagery

AbstractIn situ measurements of water depth and optical properties of a melt pond in East Greenland were collected to verify a previously developed algorithm for determining supraglacial water depths using satellite imagery. That algorithm made five simplifying assumptions which we have tested using the in situ data and laboratory analysis of water samples. We conclude that three assumptions were justified, one was not and the remaining one (substrate homogeneity) requires further study, but probably has a minor effect on the retrieved water depths and volumes. Measured water depths of 0.2–3.0m agree well with those derived from a satellite image using the algorithm. Numerically modeled depths also agree well with those from the satellite image. This new analysis demonstrates the validity of our algorithm as a means for determining meltwater volumes in supraglacial ponds and lakes.

Polarization lidar for shallow water depth measurement

A bathymetric, polarization lidar system transmitting at 532 nm and using a single photomultiplier tube is employed for applications of shallow water depth measurement. The technique exploits polarization attributes of the probed water body to isolate surface and floor returns, enabling constant fraction detection schemes to determine depth. The minimum resolvable water depth is no longer dictated by the system's laser or detector pulse width and can achieve better than 1 order of magnitude improvement over current water depth determination techniques. In laboratory tests, an Nd:YAG microchip laser coupled with polarization optics, a photomultiplier tube, a constant fraction discriminator, and a time-to-digital converter are used to target various water depths with an ice floor to simulate a glacial meltpond. Measurement of 1 cm water depths with an uncertainty of ±3 mm are demonstrated using the technique. This novel approach enables new approaches to designing laser bathymetry systems for shallow depth determination from remote platforms while not compromising deep water depth measurement.

Landscape unit based digital elevation model development for the freshwater wetlands within the Arthur C. Marshall Loxahatchee National Wildlife Refuge, Southeastern Florida

The hydrologic regime is a critical limiting factor in the delicate ecosystem of the greater Everglades freshwater wetlands in south Florida that has been severely altered by management activities in the past several decades. “Getting the water right” is regarded as the key to successful restoration of this unique wetland ecosystem. An essential component to represent and model its hydrologic regime, specifically water depth, is an accurate ground Digital Elevation Model (DEM). The Everglades Depth Estimation Network (EDEN) supplies important hydrologic data, and its products (including a ground DEM) have been well received by scientists and resource managers involved in Everglades restoration. This study improves the EDEN DEMs of the Loxahatchee National Wildlife Refuge, also known as Water Conservation Area 1 (WCA1), by adopting a landscape unit (LU) based interpolation approach. The study first filtered the input elevation data based on newly available vegetation data, and then created a separate geostatistical model (universal kriging) for each LU. The resultant DEMs have encouraging cross-validation and validation results, especially since the validation is based on an independent elevation dataset (derived by subtracting water depth measurements from EDEN water surface elevations). The DEM product of this study will directly benefit hydrologic and ecological studies as well as restoration efforts. The study will also be valuable for a broad range of wetland studies.

Cross-shore suspended sediment flux in the salt marsh pioneer zone of Chongming eastern beach in the Changjiang Estuary in China

Between April 2002 and April 2003, in situ measurements of water depth, current velocity and suspended sediment content were carried out in edge region of East Chongming salt marsh and neighboring bald flat in the Changjiang (Yangtze) Estuary under different weather conditions. Cross-shore suspended sediment flux was calculated and analyzed. The results show that under calm weather conditions, the current velocity process in bald field and salt marsh area varied differently during semidiurnal tidal cycles. Owing to current velocity asymmetry, mean SSC during flood tide phase was 1.8 times higher than that of ebb tide phase. As a result, net onshore sediment flux controlled cross-shore suspended sediment transport process and salt marsh pioneer zone was generally accreting. There was significant positive correlation between total sediment flux and quartic power of maximum water depth. It indicates that tidal ranges dominate suspended sediment transport and sedimentation process in the salt marsh pioneer zone under the calm weather condition. The sedimentation rate on the adjacent mudflat was higher than the salt marsh, which induced stable accreting of salt marsh towards the sea. The wind events enhanced SSC and current velocity during the semidiurnal tides. And the remarkable onshore net sediment flux could occur on the high marsh and mudflat close to the marsh fringe during the short period under the rough weather condition.

Hydrodynamic Processes and Bedload Transport Associated with Large-Scale Sandwaves in the Taiwan Strait

Hydrodynamic processes and bedload transport over a large-scale sandwave field were analyzed along three transects in Taiwan Strait based on measurements of water depth, current velocities within the water column, and the physical properties of the sediment at the seabed. The sandwaves in consideration have steep crests and flat troughs, with a width of 14.4–20.3 m and a length of 325–820 m. Generally, the mean H/L ratio falls in the range of large-scale sandwaves, but the ratio is larger than the average, deviating from the global trend. The H/d ratio is much higher than the global average. The current-velocity vectors at the sandwave crests, troughs, stoss sides, and lee sides turned in a clockwise manner within a tidal cycle; the current speed above the crest was relatively larger than above the trough. During the flood tide, the current speed reached a maximum in the layer 9–11 m below the water surface. During the measurement period, there was net accumulation of sediment over the study area. The migration of the sandwaves caused by bedload transport varied widely at different transects: for the three transects in consideration, migration in the flood direction occurred at two transects, with different migrating speeds; and ebb-dominated migration occurred at the third transect. The migration rate predicted by the bedload transport calculations, based on tidal current measurements, is lower than long-term observations by remote sensing, which may be due to the fact that this region is frequently influenced by storm events, and the long-term migration patterns are related to the enhanced currents and waves during storms. Further, time-velocity asymmetry of the tidal currents, as observed in the present study, may also favor the enhanced migration rate during storm events.

Testing the limits of AEM bathymetry with a floating TEM system

A floating transient electromagnetic (TEM) system (“sea ring”) simulating a low-altitude helicopter airborne electromagnetic (AEM) system was constructed to test the accuracy of the AEM method for measuring water depth and estimating sediment thickness in shallow coastal waters. A square transmitter loop [Formula: see text], plus concentric inner and outer receiver loops, was strung from masts supported by the circular sea-ring base. Data were stacked over periods from 1 to approximately [Formula: see text] and with loop heights ranging between approximately 5.5 and [Formula: see text] above sea level. The towed sea ring provides a stable platform at a known fixed altitude in calm waters. We have undertaken modeling to investigate the effect of vertical and horizontal displacements of the loops, and to compare circular and square loopgeometries, in proximity to the sea surface. With relatively long stacking times, as long as approximately [Formula: see text], the uncertainty in altitude can be reduced to very low levels. The sea ring has been deployed near Port Lincoln, Australia, in an area with known bathymetry, seawater conductivity [Formula: see text], and sediment thickness (from marine seismic). Initial 1D inversion of raw sea-ring data highlighted significant instrument calibration errors. Empirical correction factors were defined to achieve agreement between measured and modeled TEM responses at selected control points. These corrections were then applied to the entire data set. The 1D inversion of corrected sea-ring data predicted seawater depths within approximately [Formula: see text] of known depths down to [Formula: see text]. These results provide an upper limit to the accuracy that can be expected from airborne EM systems for shallow bathymetry using current technology.

Bioengineering and subjective approaches to the clinical evaluation of dry skin

Dry skin (also known as xerosis) is a cutaneous reaction pattern indicative of abnormal desquamation, which has not only cosmetic considerations, but can also lead to the penetration of irritants and allergens through the stratum corneum (SC). Over the last few decades, our understanding of the structure, composition, formation and function of the SC has advanced tremendously; however, despite these advancements, the occurrence of dry skin remains prevalent in the adult population. The clinical evaluation of dry skin is therefore of significant importance to the cosmetic industry not only for understanding the condition but also for measuring the effects of treatment. Traditionally, dry skin has been evaluated by visual inspection, however, recently a variety of bioengineering techniques have emerged enabling the investigator to objectively assess the extent of xerotic conditions. The most frequently employed methods for the evaluation of dry skin are discussed in this review, including regression testing, squametry, measurement of transepidermal water loss, epidermal hydration, profilometry, confocal Raman spectroscopy, optical coherence tomography, in vivo confocal microscopy and magnetic resonance imaging.

Development and application of the water depth measurement system using GPS and echo sounder

Development and application of the water depth measurement system using GPS and echo sounder

수중탐사용 호버링 무인잠수정 NOAH의 테스트베드 개발

This paper describes the design and performance of a hovering AUV `NOAH` constructed at Jeju National University. We analyse the dynamic performance of NOAH using simulation program and carry out depth control test at small basin. The main purpose of NOAH is to carry out fundamental tests on its attitude control and position control. Its configuration is similar to general ROV appearance for underwater works and dimension is . It has 4 thrusters of 450watt for longitudinal/lateral/vertical propulsion and is equipped with a pressure sensor for measuring water depth and a magnetic compass for measuring heading angle. The navigation of the vehicle is controlled by an on-board Pentium III-class computer, which runs with the help of the Windows XP operating system. These give us an ideal environment for developing various algorithm which are needed for developing and advanced hovering AUV.

Morphological Deformities inChironomusspp. (Diptera: Chironomidae) Larvae as a Tool for Impact Assessment of Anthropogenic and Environmental Stresses on Three Rivers in the Juru River System, Penang, Malaysia

Morphological deformities in parts of the head capsule of Chironomus spp. larvae inhabiting three polluted rivers (Permatang Rawa [PRR], Pasir [PR], and Kilang Ubi [KUR]) in the Juru River Basin, northeastern peninsular Malaysia, were studied. Samples of the fourth-instar larvae at one location in each river were collected monthly from November 2007 to March 2008 and examined for deformities of the mentum, antenna, mandible, and epipharyngis. At each sample location, in situ measurements of water depth, river width, water pH, dissolved oxygen, and water temperature were made. Samples of river water and benthic sediments were also collected monthly from each larval sample location in each river and taken to the laboratory for appropriate analysis. Total suspended solids (TSSs), ammonium-N, nitrate-N, phosphate-P, chloride, sulfate, and aluminum content in water were analyzed. Total organic matter and nonresidual metals in the sediment samples were also analyzed. Among the three rivers, the highest mean deformity (47.17%) was recorded in larvae collected from KUR that received industrial discharges from surrounding garment and rubber factories, followed by PRR (33.71%) receiving primarily residues of fertilizers and pesticides from adjacent rice fields, and PR (30.34%) contaminated primarily by anthropogenic wastes from the surrounding residential areas. Among the various head capsule structures, deformity of the mentum was strongly reflective of environmental stress and amounted to 27.9, 20.87, and 30.19% in the PRR, PR, and KUR, respectively. Calculated Lenat's toxic score index satisfactorily explained the influence of prevailing environmental variables on the severity of mentum deformities. Redundancy analysis and forward selection selected TSSs, sediment Zn, Mn, Cu, and Ni, and water pH, dissolved oxygen, water temperature, total organic matter, nitrate-N, chloride, phosphate-P, ammonium-N, sulfate, and aluminum as parameters that significantly affected some proportion of deformities. The total deformities correlated closely with deformities of mentum but only weakly with deformities in other parts of head. The total deformity incidence was strongly correlated with high contents of sediment Mn and Ni. The mentum and epipharyngis deformities incidence was highly correlated with an increase of TSSs, total aluminum, and ammonium-N and a decrease in pH and dissolved oxygen.

Relative Depth Estimation Method using Single Multispectral Image Alone

A passive remote sensing method of relative depth (a variable proportional to water depth) of shallow water is proposed. It is similar in the prediction formula with the well-known regressive method by Lyzenga et al.(2006), but is unique in that it doesn't require any auxiliary input data other than single multispectral image: the coefficients of the formula is estimated by utilizing pixels of near-zero depth extracted from image, without relying on in-situ measurements of water depth or other optical properties. The accuracies (correlation coefficient between estimated and measured depth) of the both methods are tested using a QuickBird image of a coral reef area. As a surprising result, the accuracy of the new method is found to be comparable and sometimes even superior to that of Lyzenga et al.'s method.

Effects of sea-surface conditions on passive fathometry and bottom characterization

Recently, a method has been developed that exploits the correlation properties of the ocean's ambient noise to measure water depth (a passive fathometer) and seabed layering [M. Siderius et al., J. Acoust. Soc. Am. 120, 1315-1323 (2006)]. This processing is based on the cross-correlation between the surface noise and the echo return from the seabed. To quantitatively study the dependency between processing and environmental factors such as wind speed, measurements were made using a fixed hydrophone array while simultaneously characterizing the environment. The measurements were made in 2006 in the shallow waters (25 m) approximately 75 km off the coast of Savannah, GA. A Navy tower about 100 m from the array was used to measure wind speed and to observe the sea-surface using a video camera. Data were collected in various environmental conditions with wind speeds ranging from 5 to 21 ms and wave heights of 1-3.4 m. The data are analyzed to quantify the dependency of passive fathometer results on wind speeds, wave conditions, and averaging times. One result shows that the seabed reflection is detectable even in the lowest wind conditions. Further, a technique is developed to remove the environmental dependency so that the returns estimate seabed impedance.

Relationship between body condition of American alligators and water depth in the Everglades, Florida

Feeding opportunities of American alligators (Alligator mississippiensis) in freshwater wetlands in south Florida are closely linked to hydrologic conditions. In the Everglades, seasonally and annually fluctuating surface water levels affect populations of aquatic organisms that alligators consume. Since prey becomes more concentrated when water depth decreases, we hypothesized an inverse relationship between body condition and water depth in the Everglades. On average, condition of adult alligators in the dry season was significantly higher than in the wet season, but this was not the case for juveniles/subadults. The correlation between body condition and measured water depth at capture locations was weak; however, there was a significant negative correlation between the condition and predicted water depth prior to capture for all animals except for spring juveniles/subadults which had a weak positive condition–water depth relationship. Overall, a relatively strong inverse correlation occurred at 10–49 days prior to the capture day, suggesting that current body condition of alligators may depend on feeding opportunities during that period. Fitted regression of body condition on water depth (mean depth of 10 days when condition-water depth correlation was greatest) resulted in a significantly negative slope, except for spring adult females and spring juveniles/subadults for which slopes were not significantly different from zero. Our results imply that water management practices may be critical for alligators in the Everglades since water depth can affect animal condition in a relatively short period of time.

Evaluating potassium phosphonate injections for the control of Quercus ilex decline in SW Spain: implications of low soil contamination by Phytophthora cinnamomi and low soil water content on the effectiveness of treatments

The Iberian forests are suffering severe disease and mortality as a result of decline, with Quercus ilex the major species at risk. Trunk injections with potassium phosphonate, which have been used successfully to control Phytophthora cinnamomi, were tested against decline. In an area in which P. cinnamomi was isolated, Q. ilex trees showing different degrees of decline were trunk-injected. Soil properties, and measurements of soil water content (θ) and depth to soil water table were assessed at three sites with markedly different decline incidences. Over the 5 years following the initiation of the experiment, mean symptoms among spring-treated trees and autumn-treated trees, or among trees injected twice a year (spring and autumn), once a year, and non-injected, were not significantly different. No effects of the treatments on shoot growth and acorn production were observed. However, θ values under trees which recovered from decline were higher than θ values under trees which did not recover from decline. At the site with the highest incidence of decline and tree mortality, P. cinnamomi was rarely isolated, and the presence of gravel, soil infiltration capacities and water table depth values were significantly higher than at the other sites, water stress being more likely to contribute to decline than P. cinnamomi. In areas in which θ is low, the distribution of phosphonate on the tree would be limited. Since the thresholds for phytotoxicity of potassium phosphonate in Q. ilex trees at the site studied would be higher than the amounts used, rates of the chemical slightly less than those that cause phytotoxicity should be tested.

THE CORRELATION BETWEEN WATER DEPTH AND REFLECTANCE SPECTRA IN RADIAL SUBMARINE SAND RIDGE SYSTEMS OF JIANGSU PROVINCE

Sand drift is of vital importance in water-depth remote sensing,as shown by an analysis of the reflectance spectral data and measured water depth data.The concentration of the sand drift decides the direction of the correlation coefficient between the water depth and the reflectance spectra: the correlation coefficient is lower than 0 in the clear area and higher than 0 in the high turbidity area.On such a basis,the water body can be classified before depth extraction so as to improve the depth extraction precision.The high spectral remote sensing technique can raise the extraction precision based on the simulation analysis of different spectra.