scholarly journals Tidal Oscillation and Resonance in Semi-Closed Estuaries—Empirical Analyses from the Elbe Estuary, North Sea

Water ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 848
Author(s):  
Sebastian S. V. Hein ◽  
Vanessa Sohrt ◽  
Edgar Nehlsen ◽  
Thomas Strotmann ◽  
Peter Fröhle
Keyword(s):  
Resonance Frequency ◽  
River Mouth ◽  
Tidal Wave ◽  
Tidal Range ◽  
Wave Transformation ◽  
Elbe Estuary ◽  
Harmonic Analysis Method ◽  
Tidal Constituents ◽  
Harmonic Analyses ◽  
Year 2000

Many tidal influenced estuaries and coastal basins feature tidal amplification because of, e.g., convergence and reflection. Increasing amplification rates were observed in the Elbe estuary, with consequences for construction measures, nautical manoeuvring, flood protection, riverbed morphology and ecosystems. Although many studies were conducted investigating the tidal wave transformation in estuaries, studies based on spatially well-distributed empirical data covering periods over more than a year are rare. To fill this gap, a self-developed adapted harmonic analysis method of least squares was applied to hydrographs from 25 gauges, distributed over the tidal influenced estuary from the river mouth to the tidal border which is given by the weir 160 km upstream of the river mouth. The investigation period for the harmonic analyses covers a whole nodal cycle of 18.613 a beginning in the year 2000. The tidal constituents’ oscillatory behaviour including the appearance of compound tides, generated by nonlinear shallow water processes, and the formation of reflection induced partially standing waves are determined. The tidal constituents show shared frequency-group specific partial clapotis, but also have significant differences in amplification within those groups. The latter fact contributes to the detected inverse proportionality of tidal range amplification inside the estuary to incoming tidal wave height. As reflection can cause resonance in tidal influenced rivers, tests are developed to analyse whether criteria for resonance are met. To determine the system’s specific resonance frequency, a new method was introduced with the three-parameter Lorentzian curve-fitting. As the detected resonance frequency is not close to tidal frequencies, full-established resonance of the tidal wave and of the tidal constituents is not observed in the Elbe estuary. Migrating nodes of the partially standing tidal wave hint at increasing latent resonance.

Generalized Model Study on Tidal Wave Transformation in Estuaries where Sluices are Constructed

2012 ◽  
Vol 212-213 ◽  
pp. 181-185
Author(s):  
Xin Zhou Zhang ◽  
Xiang Ming Wang ◽  
Xi Ping Dou ◽  
Xiao Dong Zhao ◽  
Ming Cheng Zhu
Keyword(s):  
Theoretical Basis ◽  
Velocity Ratio ◽  
Tidal Wave ◽  
Tidal Range ◽  
Wave Transformation ◽  
Model Design ◽  
Generalized Model ◽  
Irrigation Channel ◽  
Model Study ◽  
The Difference

A generalized model is established and theoretical basis of model design and the model layout are illustrated. Simulation study on the phenomenon of tidal wave transformation with different length of irrigation channel through generalized physical model is carried out, and several conclusions are obtained. The length of irrigation channel influences tidal wave transformation obviously, including the difference of tidal process under various conditions, different trends of tidal range along the irrigation channel and the change of velocity ratio of flood and ebb tide with the length changing.

Groundwater-level variation during semidiurnal spring tidal cycles on a sandy beach

1982 ◽  
Vol 33 (3) ◽  
pp. 377 ◽  
Author(s):  
JA Lanyon ◽  
IG Eliot ◽  
DJ Clarke
Keyword(s):  
Water Table ◽  
Groundwater Level ◽  
Sandy Beach ◽  
Time Lag ◽  
Three Dimensional ◽  
Tidal Range ◽  
Three Dimensional Flow ◽  
Groundwater Response ◽  
Tidal Constituents ◽  
Groundwater Rise

Observations of two-dimensional variations in groundwater level on beach profiles at South Beach, Wollongong, support and extend observations previously reported. Time-series curves showing water-level change at individual wells along the profiles are markedly asymmetrical and their ranges of oscillation are dependent on tidal range and distance landward of the beach face. The asymmetry is attributed to filtering processes at the beach face and in the beach, that separate the various tidal constituents. Tidally induced groundwater changes are superimposed on a three-dimensional water-table surface that is tied to the beach morphology and to groundwater recharge from the backshore zone. The three-dimensional flow net is raised and lowered as the tide rises and falls. although with some time lag between change in level of ocean water and groundwater response. The groundwater rise begins earliest in shoreline embayments and spreads landwards and outwards to higher water-table surfaces near shoreline salients and in the backshore zone. Groundwater responses, therefore. differ on the salients and in the embayments: a landward water-table slope prevails in the embayments and a seaward slope characterizes the salients.

scholarly journals COASTAL SAND MINING IN NORTHERN CALIFORNIA, U.S.A.

1972 ◽  
Vol 1 (13) ◽  
pp. 83
Author(s):  
Orville T. Magoon ◽  
John C. Haugen ◽  
Robert L. Sloan
Keyword(s):  
San Francisco ◽  
Base Material ◽  
River Mouth ◽  
Road Construction ◽  
Mining Activity ◽  
Raw Material ◽  
Tidal Range ◽  
Sand Mining ◽  
Tidal Zone ◽  
Coastal Sand

The commercial mining of sand at coastal locations along California has been a continuing activity at some sites, sporadic at others and altogether discontinued at still other sites. This mining activity includes all methods of sand mining (dragline, self-propelled bottom-dump scrapers, diesel shovels, etc.) and may be classified by littoral zone location as (1) mining from a beach foreshore or backshore area wetted by the normal tidal range, (2) mining within a river mouth or other estuary upstream from the ocean but still within the tidal zone, and (3) mining from bluff or dune areas not wetted by the normal range of tides but still within the littoral system. Processing of the sand thus mined takes place when the material is transported from the mining site, usually by end dump trucks or belt conveyor to either a fixed or a portable plant. Commercial uses of the sand thus mined fall into two general categories, (1) construction and (2) special purposes. Construction usage includes aggregate for concrete, asphalt, mortar, plaster and stucco, base material in road construction, and fill and structural backfill. Specialty uses include sand blasting and filtration material, foundry and engine sands, and raw material for manufacture of glass and ceramics. Within the area studied (see Figure 1) the Monterey Bay area has the highest concentration of mining activity. To the north, the area around Fort Bragg yields significant quantities to the commercial miner. Most of the remaining coastal sand mining activity is concentrated in the San Francisco area.

scholarly journals WAVE DECAYING DUE TO BREAKING

1966 ◽  
Vol 1 (10) ◽  
pp. 15 ◽  
Author(s):  
Makoto Nakamura ◽  
Hidehiko Shiraishi ◽  
Yasuo Sasaki
Keyword(s):  
Shallow Water ◽  
Deep Sea ◽  
River Mouth ◽  
Beach Erosion ◽  
Breaking Point ◽  
Wave Transformation ◽  
Effective Measure ◽  
Planning And Design ◽  
Sea Bottom ◽  
Sea Area

In the planning and design of coastal engineering works for the control of beach characteristics, a proper and effective measure against wave must be the most important problem to be solved. When the wave generated on the open sea approaches the shallow sea area, it will be transformed under the influence of sea bottom. For the construction works of coastal structures on a shoreline or in shallow water, the estimation of the rate of wave transformation is needed. In this concern, many reports were already published by the researchers,i. e, R.L.Wiegel, M.A.Mason,H.W. Iversen and T.Kishi. Moreover, the so-called Breaker Index which shows the breaking conditions has been obtained by the Beach Erosion Bord (U.S.A.), based on the data of field observations. Furthermore, these characteristics were investigated theoretically and experimentally by H.W. Iversen, Hamada, Sato and Kishi. Though these results show the wave transformation from the deep sea to a breaking point, there are few reports dealing with the wave transformation in the process of breaking and after a breaker zone. In the execution of coastal works projected in Ministry of Agriculture and Forestry such as shore reclamation works, coastal defence works and river mouth improvement, the wave inshore from a breaker zone often should be taken into consideration. In the past design of coastal structure, the wave acting on structures in the shallow water is calculated from the deep sea wave usually by using very rough estimation that wave height is reduced by about 30 per cent after a single breaking and wave period by about 10 per cent. Consequently, in order to analyze the wave decaying due to breaking, this paper treated with the wave transformation in the vicinity of a breaking point.

scholarly journals Study on Hydrodynamic Characteristics and Environmental Response in Shantou Offshore Area

2021 ◽  
Vol 9 (8) ◽  
pp. 912
Author(s):  
Yuezhao Tang ◽  
Yang Wang ◽  
Enjin Zhao ◽  
Jiaji Yi ◽  
Kecong Feng ◽  
...  
Keyword(s):  
Flow Field ◽  
Water Level ◽  
Tidal Current ◽  
Sea Water ◽  
High Tide ◽  
Spring Tide ◽  
River Estuary ◽  
Tidal Range ◽  
Offshore Area ◽  
Tidal Constituents

As a coastal trading city in China, Shantou has complex terrain and changeable sea conditions in its coastal waters. In order to better protect the coastal engineering and social property along the coast, based on the numerical simulation method, this paper constructed a detailed hydrodynamic model of the Shantou sea area, and the measured tide elevation and tidal current were used to verify the accuracy of the model. Based on the simulation results, the tide elevation and current in the study area were analyzed, including the flood and ebb tides of astronomical spring tide, the flood and ebb tides of astronomical neap tide, the high tide, and the low tide. In order to find the main tidal constituent types in this sea, the influence of different tidal constituents on tide elevation and tidal current in the study area was analyzed. At the same time, the storm surge model of the study area was constructed, and the flow field under Typhoon “Mangkhut” in the study area was simulated by using the real recorded data. Typhoon wind fields with different recurrence periods and intensities were constructed to simulate the change in the flow field, the sea water level, and the disaster situation along the coast. The results showed that under normal sea conditions, the sea water flows from southwest to northeast at flood tide and the flow direction is opposite at ebb tide. The tidal range is large in the northwest and small in the southeast of the study area. The tides in the study area are mainly controlled by M2, S2, K1, and O1 tidal constituents, but N2, K2, P1, and Q1 tidal constituents have significant effects on the high water level. The water level caused by typhoons increases significantly along the coast of Shantou City. In the west area of the Rong River estuary, a typhoon with a lower central pressure than 910 hPa may induce a water increase of more than 2 m.

scholarly journals ARTIFICIAL DEVIATION OF A SMALL INLET (BEVANO, NORTHERN ITALY): PREDICTION OF FUTURE EVOLUTION AND PLANNING OF MANAGEMENT STRATEGIES USING OPEN-SOURCE COMMUNITY COASTAL MODELS

2012 ◽  
Vol 1 (33) ◽  
pp. 57
Author(s):  
Paolo Ciavola ◽  
Massimo Tondello ◽  
Sandro Carniel ◽  
Mauro Sclavo
Keyword(s):  
Morphological Changes ◽  
Management Strategies ◽  
River Mouth ◽  
Tidal Range ◽  
Northern Adriatic Sea ◽  
Northern Adriatic ◽  
Future Evolution ◽  
River Flooding ◽  
Inland River ◽  
Using Data

The Bevano river flows into the northern Adriatic Sea in a microtidal-low energy wave environment. The river mouth was diverted artificially in 2006 to contrast dune erosion and decrease inland river flooding. The intervention can be considered as a low impact one as the engineering works were constructed in timber and the possibility of the inlet naturally changing its course was contemplated. An ensemble of hydraulic/morphological scenarios was simulated using data from field surveys and a coupled numerical model. The aim of the modeling was to understand the morphological changes caused by extreme hydro-meteorological events and the relationships between the inlet and the adjacent beaches. Additionally, the probability of a second inlet opening either by overwashing or river breaching was another important topic considered for management purposes. The modeling found that, a second inlet can actually be opened under a 30 year flood occurring without any significant wave action. For other conditions, the current inlet will be the main source of water escape at sea. Finally, the modeling results confirmed the dominance of the ebb tide in creating a small ebb delta/swash bar, with many similarities with other inlets exposed to a larger tidal range. Currently the management strategy by competent authorities is a minimum maintenance option, with yearly repairs of the timber structures.

scholarly journals Surface currents in the Porsanger fjord in northern Norway

2016 ◽  
Vol 37 (3) ◽  
pp. 337-360 ◽  
Author(s):  
Malgorzata Stramska ◽  
Andrzej Jankowski ◽  
Agata Cieszyńska
Keyword(s):  
Sea Level ◽  
Barents Sea ◽  
Surface Current ◽  
Current Data ◽  
Tidal Range ◽  
Surface Currents ◽  
Tidal Component ◽  
Level Data ◽  
Sea Level Oscillations ◽  
Tidal Constituents

Abstract We describe surface currents in the Porsanger fjord (Porsangerfjorden) located in the European Arctic in the vicinity of the Barents Sea. Our analysis is based on surface current data collected in the summer of 2014 using High Frequency (WERA, Helzel Messtechnik GmbH) radar system. One of our objectives was to separate out the tidal from the nontidal components of the currents and to determine the most important tidal constituents. Tides in the Porsanger fjord are substantial, with tidal range on the order of about 3 m. Tidal analysis attributes to tides about 99% of variance in sea level time series recorded in Honningsvaag. The most important tidal component in sea level data is the M2 component, with amplitude of ~90 cm. The S2 and N2 constituents (amplitude of ~20 cm) also play a significant role in the semidiurnal sea level oscillations. The most important diurnal component is K1 with amplitude of about 8 cm. The most important tidal component in analyzed surface currents records is the M2 component. The second most important component is the S2. Our results indicate that in contrast to sea level, only about 10-30% of variance in surface currents can be attributed to tidal currents. This means that about 70-90% of variance is due to wind-induced and geostrophic currents.

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