scholarly journals Propagation of tides along a river with a sloping bed

2019 ◽  
Vol 872 ◽  
pp. 39-73 ◽  
Author(s):  
K. Kästner ◽  
A. J. F. Hoitink ◽  
P. J. J. F. Torfs ◽  
E. Deleersnijder ◽  
N. S. Ningsih
Keyword(s):  
Sea Level ◽  
River Discharge ◽  
River Flow ◽  
River Mouth ◽  
Tidal River ◽  
Tidal Range ◽  
Narrow Channels ◽  
Tidal Waves ◽  
Frictional Damping ◽  
Set Up

Conceptually, tidal rivers are seen as narrow channels along which the cross-section geometry remains constant and the bed is horizontal. As tidal waves propagate along such a channel, they decrease exponentially in height. The more rapid the decrease, the stronger the river flow. Near the coast, the tidally averaged width and depth change little throughout the year, even if the river discharge varies strongly between the seasons. However, further upstream, the water depth varies considerably with the river discharge. Recent observations from the Kapuas River, Indonesia, show that the water surface forms a backwater profile when the river flow is low. In this case, the depth converges, i.e. it gradually decreases between the river mouth and the point where the bed reaches sea level. This effect distinctly influences how tidal waves propagate up river so that their wave height does not decrease exponentially any more. We present a theoretical analysis of this phenomenon, which reveals several so far overlooked aspects of river tides. These aspects are particularly relevant to low river flow. Along the downstream part of the tidal river, depth convergence counteracts frictional damping so that the tidal range is higher than expected. Along the upstream parts of the tidal river, the low depth increases the damping so that the tide more rapidly attenuates. The point where the bed reaches sea level effectively limits the tidal intrusion, which carries over to the overtide and the subtidal water level set-up.

scholarly journals Determination of the length of Bogowonto double jetty as the river mouth stabilization

2021 ◽  
Vol 930 (1) ◽  
pp. 012027
Author(s):  
T E Bhakty ◽  
A H Swasono ◽  
N Yuwono ◽  
A F Ghalizhan ◽  
T Widyasari
Keyword(s):  
Coastal Area ◽  
River Discharge ◽  
River Flow ◽  
River Mouth ◽  
Tidal Range ◽  
Wet Season ◽  
Flow Through ◽  
The One ◽  
River Mouths

Abstract One of the problems around estuaries with the wave-dominated combination of a small tidal range and low river discharges in the dry season was the mouth closed by a sand barrier. Longshore sediment flows silted up the river mouth while river flows were insufficiently large for flushing sand barriers. When the wet season started, river discharge suddenly enlarged. Discharge can’t flow through the river mouth due to being hindered by the sand barrier. The consequence was that the hinterlands were inundated. Yogyakarta International Airport (YIA) is located in a coastal area of Kulon Progo regency, between two river mouths (Bogowonto river and Serang River). The two rivers have unstable river mouths. The double Jetty had been built at the Bogowonto river, but its condition was damaged. Meanwhile, the breakwater was constructed at the river mouth Serang and called Tanjung Adikarto. Double Jetties will be built to stabilize the Bogowonto river mouth. The purpose of this paper is to provide an overview of the length of the Jetty to be more effective in stabilizing the Bogowonto river mouth. Therefore, so that more easily opened by river flow and does not cause excessive erosion on the one side of the Jetty.

Salt water intrusion in the Pearl River networks, China

2020 ◽  
Author(s):  
Wei Zhang ◽  
Rongxiang Zhou ◽  
Xiaomei Ji
Keyword(s):  
Sea Level ◽  
River Discharge ◽  
Salt Water ◽  
Rapid Development ◽  
Tidal Range ◽  
Pearl River ◽  
River Networks ◽  
Salt Water Intrusion ◽  
Water Intrusion ◽  
The Pearl River

<p>The Pearl River networks is a typical river networks system with channel density ranging from 0.81-0.88m/m<sup>2</sup>. Recent years, with the rapid development of economy, the intensive human activities have great impacts on the networks system. Sand excavation is the most severe one, which directly led to the averaged 4-6m riverbed downcutting over the Pearl River networks. Consequently, salt water intrusion has become much serious than it was before. In this study, a coupled 1-D river networks and 3-D estuarine combined numerical model has been established to evaluate the influence of bathymetry changes and sea level rising on the salt water intrusion in the river networks. Two period of bathymetries in 1990s and 2000s have been used to simulate the length of salt water intrusion (LSR). It is found that the LSR in 2000s was 24 km farther upstream than that in 1990s. However, the LSR is no more than 3 km when sea level rises by 30 cm. This implies that impact of bathymetry changes overwhelms the sea level rise on LSR. The result also shows that LSR has the negative and positive correlation with river discharge and tide range respectively, which means that LSR will decrease and increase with river discharge and tidal range increasing. Furthermore, it is quite interesting to notice that the LSR is also quite relative to the flow ratio at the apex of the delta. With the same river discharge from the upper stream, the more the discharge come from the West River, the less LSR will happen, which would be quite useful to the authority to transfer the water to control the salt water intrusion in Pearl River networks.</p>

scholarly journals Does HadGEM3-GC3.1 GCM overestimate land precipitation at high resolution? A constraint based on observed river discharge

2021 ◽  
Author(s):  
Omar V. Müller ◽  
Pier Luigi Vidale ◽  
Benoît Vannière ◽  
Reinhard Schiemann ◽  
Patrick C. McGuire
Keyword(s):  
High Resolution ◽  
Bias Correction ◽  
River Discharge ◽  
River Flow ◽  
River Mouth ◽  
Mountainous Regions ◽  
Novel Approach ◽  
The World ◽  
Global Land ◽  
Precipitation Increase

AbstractPrevious studies showed that high-resolution GCMs overestimate land precipitation when compared against observation-based data. Particularly, high-resolution HadGEM3-GC3.1 shows a significant precipitation increase in mountainous regions, where the scarcity of gauge stations increases the uncertainty of gridded observations and reanalyses. This work evaluates such precipitation uncertainties indirectly through the assessment of river discharge, considering that an increase of ~10% in land precipitation produces ~28% more runoff when the resolution is enhanced from 1° to 0.25°, and ~50% of the global runoff is produced in 27% of global land dominated by mountains. We diagnosed the river flow by routing the runoff generated by HadGEM3-GC3.1 low- and high-resolution simulations. The river flow is evaluated using a set of 344 monitored catchments distributed around the world. We also infer the global discharge by constraining the simulations with observations following a novel approach that implies bias correction in monitored rivers with two methods, and extension of the correction to the river mouth, and along the coast. Our global discharge estimate is 47.4±1.6×103km3yr−1, which is closer to the original high-resolution estimate (50.5 × 103km3yr−1) than to the low-resolution (39.6 × 103km3yr−1). The assessment suggests that high-resolution simulations performbetter in mountainous regions, either because the better-defined orography favours the placement of precipitation in the correct catchment, leading to a more accurate distribution of runoff, or the orographic precipitation increases, reducing the dry runoff bias of coarse resolution simulations. However, high-resolution slightly increases wet biases in catchments dominated by flat terrain. The improvement of model parameterizations and tuning may reduce the remaining errors in high-resolution simulations.

scholarly journals How winds and river discharge affect circulation in a mesotidal estuary, San Francisco Bay, USA

2022 ◽  
Author(s):  
Qianqian Liu ◽  
Huijie Xue ◽  
Fei Chai ◽  
Zhengui Wang ◽  
Yi Chao ◽  
...  
Keyword(s):  
San Francisco ◽  
River Discharge ◽  
River Flow ◽  
San Francisco Bay ◽  
Integrated System ◽  
Wind Forcing ◽  
Salt Flux ◽  
Tidal Range ◽  
Salt Intrusion

Previous studies suggest importance of wind forcing on salt intrusion length and salt flux in river-dominated microtidal estuaries (with tidal range < 2 m). In this study, we investigate the role of wind forcing on salt intrusion in a mesotidal estuary, San Francisco Bay (SFB), with tidal ranges between 2 m and 4 m, through an open-source model of high transferability, the Semi-implicit Cross-scale Hydroscience Integrated System Model (SCHISM). Meanwhile, we investigate circulation and salinity variation of San Francisco Bay. The model’s performance in hydrodynamics at tidal, spring/neap and seasonal time scales is validated through model-observation comparisons. Through realistically forced and process-oriented experiments, we demonstrate that spring/neap tides can cause fortnightly variations in salinity and currents by modulating vertical mixing and stratification; and seasonal variability of circulation in North Bay is determined by change of river discharge and modified by winds, while in South Bay it is dominated by wind-driven flows. Furthermore, we revealed the role of wind on X2 (the distance from the Golden Gate Bridge to the 2-PSU isohaline at the bottom). The model results show that X2 is primarily influenced by river flow and proportional to river flow to the ¼ power. Meanwhile, wind plays a secondary role in modifying X2 by increasing X2 from 0 to 5 km during low discharge period, while spring/neap tide modulation on X2 is negligible but important for salt balance in sub-regions downstream of X2.

scholarly journals Impacts of Sea Level Rise and River Discharge on the Hydrodynamics Characteristics of Jakarta Bay (Indonesia)

Water ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1384 ◽  
Author(s):  
Martin Yahya Surya ◽  
Zhiguo He ◽  
Yuezhang Xia ◽  
Li Li
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
River Discharge ◽  
River Mouth ◽  
Ocean Model ◽  
Phase Lag ◽  
Tidal Component ◽  
Inundation Area ◽  
Current Magnitude ◽  
Coastal Ocean Model

Jakarta city has been vulnerable to sea level rise and flooding for many years. A Giant Seawall (GSW) was proposed in Jakarta Bay to protect the city. The impacts of sea level rise and river discharge on the tidal dynamics in Jakarta Bay and flooding areas in Jakarta city were investigated using the finite-volume coastal ocean model (FVCOM). Model results showed that the bay is diurnally dominated by the K1 tidal component. The diurnal tides propagate westward, while the semidiurnal tides propagate eastward in the bay. The rise of sea level increases the diurnal tidal component and the inundation areas due to the increased tidal forcing: when considering a sea level rise of 0.6 m, the K1 amplitude increases by ~1% (0.25 cm) near the coastline and the current magnitude increases by 16.6% (0.05 m/s). The inundation area increases with the sea level rise in the low land elevation areas occurring near the coastlines: the inundation area increased by 29.68 km2 (7.1%) with a sea level rise of 0.6 m. The increase of river discharge amplified the diurnal tidal component as well as the inundation areas at the river mouth due to increased fluvial forcing: if 10 times the mean river discharge occurs, the K1 amplitude increases by ~1% (0.25 cm) and the current magnitude increases by 100% (0.4 m/s), and the inundation areas increase by 26.61 km2 (6.2%). The K1 tidal phase remains almost unchanged under both the sea level rise and river discharge conditions. The combined increase of sea level rise and the river discharge amplifies the inundation areas and the tidal currents due to increased tidal and fluvial forcing. The construction of GSW would decrease the tidal prism and dissipation effects of the bay, thus slightly increasing the K1 amplitude of the tidal level: by less than 1% (0.2 cm). There would be no significant change of phase lag for the K1 component. Although this study is site specific, the findings could be applied more widely to any open-type bays.

scholarly journals Contribution of the Amazon River Discharge to Regional Sea Level in the Tropical Atlantic Ocean

Water ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 2348 ◽  
Author(s):  
Pierrick Giffard ◽  
William Llovel ◽  
Julien Jouanno ◽  
Guillaume Morvan ◽  
Bertrand Decharme
Keyword(s):  
Atlantic Ocean ◽  
Interannual Variability ◽  
Sea Level ◽  
River Discharge ◽  
River Mouth ◽  
Amazon River ◽  
Tropical Atlantic ◽  
Tropical Atlantic Ocean ◽  
Seasonal And Interannual Variability ◽  
Mean State

The Amazon River is by far the largest river by volume of water in the world, representing around 17% of the global riverine discharge to the oceans. Recent studies suggested that its impact on sea level is potentially important at global and regional scales. This study uses a set of regional simulations based on the ocean model NEMO to quantify the influence of the Amazon runoff on sea level in the Tropical Atlantic Ocean. The model is forced at its boundaries with daily fields from the ocean reanalysis GLORYS2V4. Air-sea fluxes are computed using atmospheric variables from DFS5.2, which is a bias-corrected version of ERAinterim reanalysis. The particularity of this study is that interannual daily runoffs from the up-to-date ISBA-CTRIP land surface model are used. Firstly, mean state of sea level is investigated through a comparison between a simulation with an interannual river discharge and a simulation without any Amazon runoff. Then, the impact of the Amazon River on seasonal and interannual variability of sea level is examined. It was shown that the Amazon River has a local contribution to the mean state sea level at the river mouth but also a remote contribution of 3.3 cm around the whole Caribbean Archipelago, a region threatened by the actual sea level rise. This effect is mostly due to a halosteric sea level contribution for the upper 250 m of the ocean. This occurs in response to the large scale advection of the plume and the downward mixing of subsurface waters at winter time. The Amazon discharge also induces an indirect thermosteric sea level contribution. However, this contribution is of second order and tends to counterbalance the halosteric sea level contribution. Regional mass redistributions are also observed and consist in a 8 cm decrease of the sea level at the river mouth and a 4.5 increases on continental shelves of the Gulf of Mexico and Caribbean Sea. In terms of variability, simulations indicate that the Amazon discharge may contributes to 23% and 12% of the seasonal and interannual sea level variances in the Caribbean Archipelago area. These variances are first explained by the Amazon time mean discharge and show very weak sensitivity to the seasonal and interannual variability of the Amazon runoff.

scholarly journals Upstream extension of a bottom-advected plume and its mechanism: The case of the Yellow River

2021 ◽  
Author(s):  
Xiaojie Yu ◽  
Xinyu Guo ◽  
Huiwang Gao ◽  
Tao Zou
Keyword(s):  
River Discharge ◽  
Yellow River ◽  
River Mouth ◽  
River Plume ◽  
Residual Current ◽  
Tidal Range ◽  
The Yellow River ◽  
Dimensionless Number ◽  
Discharge Condition ◽  
Advection Term

AbstractHydrographic surveys have revealed that the Yellow River plume propagates in the direction opposite to that of a Kelvin wave (upstream) under a low river discharge condition, but turns downstream as the river discharge increases. A numerical model reproduced the upstream extension of the plume under the low river discharge condition and the transition to the downstream direction under the high river discharge condition, and confirmed that the summer wind is not the necessary condition for upstream extension of the plume. With the condition of low river discharge, the model also indicated the dependence of the upstream extension of the plume on the tidal range: extending upstream in spring tide but turning downstream in neap tide. The upstream movement of the plume results from the upstream transport of freshwater that depends on the upstream tide-induced residual current around the river mouth and the downstream density-driven current around the offshore plume front. With the condition of high river discharge, the upstream tide-induced residual current cannot compete with the downstream density-driven current and the plume turns downstream. Momentum analysis confirms the important roles of advection term and viscosity term in the condition of low river discharge and the shift to a Coriolis force-dominated system under high river discharge condition. An idealized model study suggests a dimensionless number for the river discharge changing the river plume extension from upstream to downstream under a specific upstream ambient current around the river mouth.

scholarly journals Flow dynamics in large tidal delta of the Northern Dvina River: 2D simulation

2018 ◽  
Vol 20 (4) ◽  
pp. 798-814 ◽  
Author(s):  
Andrei M. Alabyan ◽  
Serafima V. Lebedeva
Keyword(s):  
Model Development ◽  
River Mouth ◽  
Storm Surges ◽  
Flow Dynamics ◽  
Tidal River ◽  
Tidal Range ◽  
Model Errors ◽  
Sea Level Changes ◽  
2D Simulation ◽  
Delta Branches

Abstract A numerical modelling of flow dynamics in a tidal river mouth of comprehensive morphology is assumed to be one of the most effective methods of both scientific research and civil engineering projects. Realistic results of simulations can be obtained only on the basis of field observations. This approach is realized for a 2D hydrodynamic model of the Northern Dvina River mouth area. The Northern Dvina delta has a very complicated distributary network and suffers from both spring snow-melt floods and autumn storm surges. The STREAM_2D software package based on the 2D shallow water equations was used for the model development. The model was calibrated and validated on the background of water level data at state gauges and special water discharges measurements in the essential delta branches during the semi-diurnal tidal cycles. Sensitivity tests were provided to evaluate the most significant reasons for model errors. It was discovered that the distribution of roughness coefficients amidst delta channels and floodplain does not affect the flow dynamics in the delta significantly. However, the tidal range variations over a neap-spring cycle and mean sea level changes along the delta marine edge are of major importance.

scholarly journals Exploring the partial use of the Mo.S.E. system as effective adaptation to rising flood frequency of Venice

2021 ◽  
Vol 21 (12) ◽  
pp. 3629-3644
Author(s):  
Riccardo A. Mel
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Venice Lagoon ◽  
Flood Frequency ◽  
Tidal Range ◽  
Relative Sea Level ◽  
Relative Sea Level Rise ◽  
Set Up ◽  
Flooding Events ◽  
The Impact

Abstract. The Venice lagoon (Italy) is particularly vulnerable to the impact of subsidence and sea level rise driven by climate change. Some structural measures have been adopted over time to protect Venice from flooding, among which a system of flap gates (Experimental Electromechanical Module, Mo.S.E., system) has been operational in the testing phase since October 2020. However, relative sea level rise and wind set-up pose relevant management challenges, as a frequent closing of the lagoon would have negative impacts on flushing capacity, the fishing industry, and port activities. Here, the focus is on the hydrodynamic effects of a partial closure of the Mo.S.E. barriers that, compared to closing all the three inlets of the lagoon, could play a role in reducing the economic and environmental impacts of the Mo.S.E. system. The main goal is to identify the flooding events that can be counteracted by closing only the Lido inlet, which is the closest to the city of Venice. Based on the tidal and meteorological dataset collected in the period 2000–2019, a robust modelling exercise identifies a linear relationship between tidal range and reduction of the sea level peaks, which results in the protection of all urban settlements within the lagoon from two-thirds of the flooding events up to a relative sea level rise of +0.4 m.

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