Measurements of Tidal Current Velocities in the Folda Fjord, Norway, With the Use of a Vessel Mounted ADCP

2014 ◽  
Author(s):  
Nicole Carpman ◽  
Mats Leijon
Keyword(s):  
Tidal Current ◽  
Energy Resource ◽  
Acoustic Doppler Current Profiler ◽  
Renewable Energy Resource ◽  
Mean Velocity ◽  
Average Width ◽  
First Approximation ◽  
Current Profiler ◽  
Current Water ◽  
Mean Current

Measurements of tidal current water velocities is an important first step in evaluating the potential for a tidal site to be used as a renewable energy resource. For this reason, on site measurements are performed at the inlet of a fjord situated at the coast of Norway. The site has an average width of 580 m and a depth of 10–15 m which is narrow and shallow enough to give rise to water velocities that can be of use for energy conversion. With the use of an Acoustic Doppler Current Profiler (ADCP) cross-section measurements are conducted along four transects. The measurements covered flood and ebb currents around one tide and the data give a first approximation of the magnitude and distribution of the flow field. Depth averaged mean current velocities are calculated along the transects for horizontal bins with sizes in the order of 50 × 50 m. Maximum mean velocity for the flood currents were 1.31 m/s and 1.46 m/s for the ebb currents. The measurements show that even a small amount of data can give an indication of the potential and characteristics of the site.

Observations of Nepheloid Layers in the Yangtze Estuary, China, Through Phase-Corrupted Acoustic Doppler Current Profiler Speeds

2012 ◽  
Vol 46 (4) ◽  
pp. 60-70 ◽  
Author(s):  
Zhenyi Cao ◽  
Xiao Hua Wang ◽  
Weibing Guan ◽  
Les J. Hamilton ◽  
Qi Chen ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Acoustic Doppler Current Profiler ◽  
Yangtze Estuary ◽  
Fluid Mud ◽  
Nepheloid Layer ◽  
The Yangtze Estuary ◽  
Mean Velocity ◽  
The North ◽  
Navigation Channel ◽  
Current Profiler

AbstractA bottom quadrapod was deployed from March 29 to April 5, 2009 to measure bottom boundary layer (BBL) flows and nepheloid layer properties in the Deepwater Navigation Channel in the North Passage of Shanghai Port in the Yangtze estuary. Using a downward-looking acoustic Doppler current profiler (ADCP) and acoustic Doppler velocimeter, detailed measurements of mean velocity and turbulence distribution within 1 m above the seabed were obtained. It appears that corrupted speeds measured for the deeper bins are caused by formation of the nepheloid layer at the seabed, implying that the ADCP is not a suitable instrument to measure current velocities in the bins nearest the seafloor. A statistical clustering method was used to characterize the current profiles in the BBL. The majority of current profiles within the BBL had a simple shape with current speed monotonically decreasing with depth, reflecting a logarithmic boundary layer. Phase-corrupted ADCP speeds measured for bins close to the bottom are shown to be useful as proxies to indicate the presence of primary and secondary lutoclines/nepheloid layers. A lutocline is a sediment-induced density gradient or pycnocline. The primary lutocline is closest to the bottom, and below it is the nepheloid layer, which is commonly composed of fluid mud. The proxies indicated that a nepheloid layer formed in the neap tide when the current velocity 1 m above the seabed dropped below a threshold of 0.65 m/s. The lutocline height was indicated to be about 0.2 m above the seabed. A secondary lutocline in the water column was also observed in the second half of the record, when the lowest maximum currents occurred.

A Comparison of an Unmanned Survey Vessel to Manned Vessels for Nearshore Tidal Current and Transport Measurements

2011 ◽  
Vol 45 (5) ◽  
pp. 71-77 ◽  
Author(s):  
Eddie Weeks ◽  
Chunyan Li ◽  
Harry Roberts ◽  
Richard F. Shaw ◽  
Nan Walker
Keyword(s):  
Energy Efficiency ◽  
Water Use ◽  
Current Velocity ◽  
Autonomous Vehicles ◽  
Tidal Current ◽  
Acoustic Doppler Current Profiler ◽  
Side Scan Sonar ◽  
Coastal Embayments ◽  
Current Profiler ◽  
Chirp Sonar

AbstractThe focus of marine autonomous vehicles has largely been for offshore applications. The use of such observational platforms in estuaries and coastal embayments has been limited by the designs of the widely used AUVs, which are mostly for open ocean studies. Here we discuss the development and testing of an automated unmanned boat for shallow water use for (1) current velocities using an acoustic Doppler current profiler, (2) bathymetry using an echo sounder, (3) seabed configuration using a side-scan sonar, or (4) shallow, sub-bottom stratigraphy using a chirp sonar. After 91 h and 453 km of total distance surveyed, results demonstrate the numerous advantages this automated boat (Auto-boat) possesses over manned survey vessels. For example, the Auto-boat had the advantage in the accuracy of repeating a planned route continuously over at least a tidal cycle to resolve tidal and subtidal current velocity profiles. It provides endurance, energy efficiency, ease of operation, and capability of coverage of shallow areas close to shore.

scholarly journals Identifikasi Arus Pasang Surut di Perairan Kemujan, Karimunjawa Berdasarkan Data Pengukuran Acoustic Doppler Current Profiler

2021 ◽  
Vol 24 (2) ◽  
pp. 247-254
Author(s):  
Elis Indrayanti ◽  
Denny Nugroho Sugianto ◽  
Purwanto Purwanto ◽  
Hendry Syahputra Ropinus Siagian
Keyword(s):  
Tidal Current ◽  
Acoustic Doppler Current Profiler ◽  
Tidal Currents ◽  
Residual Current ◽  
Least Square ◽  
Ocean Currents ◽  
Velocity Data ◽  
Raw Data ◽  
Current Profiler ◽  
X 24

Ocean currents are dynamic hydro-oceanographic parameters which is play an important role in the transport of nutrients, larvae, sediment, and so on. Therefore, the identification of ocean currents including velocity, direction, sea level and the type of currents important to be studied. The research was conducted in Kemujan Water, Karimunjawa. Data for this research is based on velocity data measured using the Acoustic Doppler Current Profiler (ADCP) for 3 x 24 hours. Furthermore, the raw data of the measurement are analyzed using least square methods to obtain the characteristic of tidal current. The total current is separated into tidal currents and residual current (non-tidal currents). Result shown that the characteristic of current in Kemujan Water, Karimunjawa was tidal current. Tidal current moves bi-directional, toward the northeast and the southwest.. Arus laut merupakan parameter hidro-oseanografi yang dinamis dan mempunyai peran penting dalam transpor nutrien, larva, material, dan lain sebagainya. Oleh karena itu identifikasi arus laut meliputi kecepatan, arah, elevasi muka air laut dan tipe arus laut perlu untuk dikaji. Penelitian dilaksanakan di Perairan Kemujan  yang merupakan salah satu gugusan pulau di Karimunjawa. Data  yang dianalisa merupakan data kecepatan arus hasil pengukuran langsung menggunakan Acoustic Doppler Current Profiler (ADCP) selama 3x24 jam. Selanjutnya raw data hasil pengukuran diolah dengan metode least square untuk mengetahui karakteristik arus. Arus total dipisahkan menjadi arus pasang surut dan arus non-pasang surut (residu). Hasil penelitian menunjukkan bahwa prosentase arus pasang surut lebih besar dari arus residu, sehingga arus di Perairan Kemujan, Karimunjawa teridentifikasi sebagai arus pasang surut. Arus  bergerak secara bertolak belakang (bi-directional) yaitu pada saat surut menuju pasang arah arus menuju ke timur laut dan pada saat pasang menuju surut arah arus menuju ke barat daya.

scholarly journals Analysis of acoustic Doppler current profiler mean velocity measurements in shallow flows

2020 ◽  
Vol 74 ◽  
pp. 101755
Author(s):  
Matthew R. Klema ◽  
Abdul G. Pirzado ◽  
S. Karan Venayagamoorthy ◽  
Timothy K. Gates
Keyword(s):  
Acoustic Doppler Current Profiler ◽  
Velocity Measurements ◽  
Mean Velocity ◽  
Shallow Flows ◽  
Current Profiler

scholarly journals Resource Assessment of Tidal Stream Power in Pakiputan Strait, Davao Gulf, Philippines

2021 ◽  
Vol 11 (3) ◽  
pp. 7233-7239
Author(s):  
E. V. Palconit ◽  
J . R. Villanueva ◽  
N. J. Enano ◽  
M. J. Buhali ◽  
A. C. Mascariñas ◽  
...  
Keyword(s):  
Energy Resource ◽  
Acoustic Doppler Current Profiler ◽  
Tidal Energy ◽  
Resource Assessment ◽  
The Philippines ◽  
Dynamics Modeling ◽  
Stream Power ◽  
Marine Energy ◽  
Current Profiler ◽  
Energy Conversion Systems

During the last years, there are ongoing efforts on the development of tidal energy conversion systems in the Philippines. This study conducts tidal energy resource assessment in the Pakiputan Strait following a methodology outlined as stage 2a tidal resource assessment published by the European Marine Energy Centre (EMEC). The study assessed the preliminary results of the tidal velocities at Pakiputan Strait with a mean spring peak velocity (Vmsp) of 1.7m/s at 3m from the water surface from 15 days of continuous data collection using a seabed-mounted acoustic Doppler current profiler. This corresponded to an estimated Annual Energy Production (AEP) of 1350kWh/y for 1m2 of capture area of the generic device. Sensitivity analysis showed that the spatial distribution of hydrodynamic model results does not vary significantly with variations in certain input parameters. It further showed that a 10% decrease in the nominal value of Vmsp on-site led to a 15% decrease in the nominal value of AEP, while a 10% increase in the nominal value of Vmsp led to a 30% increase in the nominal value of AEP, assuming that the considered Vmsp still corresponded to the velocity distribution from observations. A static survey and the use of computational fluid dynamics modeling are recommended to further enhance the analysis of the study.

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