High-quality wind field data are key to improving the accuracy of storm surge simulations in coas... more High-quality wind field data are key to improving the accuracy of storm surge simulations in coastal and estuarine water. These data are also of great significance in studying the dynamic processes in coastal areas and safeguarding human engineering structures. A directional correction method for ECMWF reanalysis wind data was proposed in this paper based on the correlation with the measured wind speed and direction. The results show that the accuracies of wind speed and direction were improved after being modified by the correction method proposed in this paper. The modified wind data were applied to drive the storm surge model of the Yangtze Estuary for typhoon events, which resulted in a significant improvement to the accuracy of hindcasted water levels. The error of the hindcasted highest water levels was reduced by 16–19 cm.
Predicting the meso-scale morphological evolution of our shorelines remains a major challenge for... more Predicting the meso-scale morphological evolution of our shorelines remains a major challenge for coastal management. The main aim of this paper is to use long-term coastal monitoring data of beach profile elevations within the Suffolk coast (east coast of the United Kingdom) to investigate meso-scale linkages between physical processes and coastal response. Patterns of beach behaviour are investigated using Empirical Orthogonal Function (EOF) and links between wave climate and beach response are explored through Canonical Correlation Analysis (CCA). The datasets consist of detailed nearshore wave measurements and profile surveys of the coastal frontage covering a period of over 22 years. The structure of the datasets and the data handling methods are described. Some results and interpretation of the analyses are presented. In particular we find a strong correlation between the first temporal eigenfunction of beach profiles and the trend in beach volume at three sites with very diff...
Due to the strong nonlinear interaction with river discharge, tides in estuaries are characterise... more Due to the strong nonlinear interaction with river discharge, tides in estuaries are characterised as nonstationary and their mechanisms are yet to be fully understood. It remains highly challenging to accurately predict estuarine water levels. Machine learning methods, which offer a unique ability to simulate the unknown relationships between variables, have been increasingly used in a large number of research areas. This study applies the LightGBM model to predicting the water levels along the lower reach of the Columbia River. The model inputs consist of the discharges from two upstream rivers (Columbia and Willamette Rivers) and the tide characteristics, including the tide range at the estuary mouth (Astoria) and tide constituents. The model is optimized with the selected parameters. The results show that the LightGBM model can achieve high prediction accuracy, with the root-mean-square-error values of water level being reduced to 0.14 m and the correlation coefficient and skill...
Water transparency, measured with Secchi disk depth (SDD), is an important parameter for describi... more Water transparency, measured with Secchi disk depth (SDD), is an important parameter for describing the optical properties of a water body. This study evaluates variations of SDD and related impact factors in the Bohai and Yellow Seas (BYS). Based on a new mechanistic model proposed by Lee et al. (2015) applied to MODIS remote sensing reflectance data, climatological SDD variation from 2003 to 2019 was estimated. The annual mean images showed an increasing trend from the coastal zone to the deep ocean. Lower values were found in the Bohai Sea (BHS), while higher values observed in the center of the southern Yellow Sea (SYS). Additionally, the entire sea has shown a decreasing temporal tend, with the variation rate lowest in the BHS at 0.003 m y−1, and highest in the SYS at 0.015 m y−1. However, the weak increasing trend that appeared since 2017 suggests that water quality seems to have improved. Further, it displayed seasonal patterns of low in winter and spring and high in summer a...
A water-retaining curtain (WRC) has become a useful facility in selective withdrawal and sediment... more A water-retaining curtain (WRC) has become a useful facility in selective withdrawal and sedimentation control, but the force analysis of a curved curtain is still lacking. Based on flume experimental tests and numerical simulations, this paper analyzes the variation laws of pressure difference and thrust of WRC. The results show that under the uniform inflow condition, the distribution of pressure difference on the WRC is relatively even, and the maximum value is located at the upper part of the curtain. When arc length–height ratio increases, the location of maximum pressure difference gets lower. In addition, the variation law of thrust of WRC conforms to the classical resistance equation. The drag coefficient is found to fit a power function of the water-retaining ratio, a second-degree polynomial function of arc length–height ratio, and linear function of inclination ratio. The results also yield a simplified forecasting formula of thrust of WRC which is proposed and verified u...
Journal of Atmospheric and Oceanic Technology, 2019
Influenced by river discharge, the tidal properties of estuarine tides can be more complex than t... more Influenced by river discharge, the tidal properties of estuarine tides can be more complex than those of oceanic tides, which makes the tidal prediction less accurate when using a classical tidal harmonic analysis approach, such as the T_TIDE model. Although the nonstationary tidal harmonic analysis model NS_TIDE can improve the accuracy for the analysis of tides in a river-dominated estuary, it becomes less satisfactory when applying the NS_TIDE model to a mesotidal estuary like the Yangtze estuary. Through the error source analysis, it is found that the main errors originate from the low frequency of tidal fluctuation. The NS_TIDE model is then modified by replacing the stage model with the frequency-expanded tidal–fluvial model so that more subtidal constituents, especially the “atmospheric tides,” can be taken into account. The results show that the residuals from tidal harmonic analysis are significantly reduced by using the modified NS_TIDE model, with the yearly root-mean-squ...
In this paper, results of sediment transport at Exe Estuary, Devon, UK, obtained from a process-b... more In this paper, results of sediment transport at Exe Estuary, Devon, UK, obtained from a process-based model under a number of wave and tide scenarios, are presented. This study uses a nested modelling system, which consists of an oceanic scale wave model WAM and a tide/surge model POLCOMS, to transform the meteorological information to nearshore wave and tide conditions for a fine resolution local coastal process-based model to carry out detailed predictions of nearshore hydrodynamics and morphodynamics at the study area. The work is focused on studying the impacts of yearly and 1 in 50 year return period storm events on morphology at the mouth of the Exe Estuary and the adjacent coasts. Comparisons of model results are made with the beach survey data carried out by the local authorities in March 2008, in addition to the model tests on both yearly calm and storm conditions in November 2006.
In this paper, we show how the methodology based on the Source-Pathway-Receptor-Consequence (SPRC... more In this paper, we show how the methodology based on the Source-Pathway-Receptor-Consequence (SPRC) approach can be used to identify the risks of flooding and erosion. The methodology is applied to the Teign Estuary in Devon, UK to define the linkages between physical loads (waves, tides), sea defences, areas liable to flooding and the impacts of flooding.
Proceedings of the ICE - Maritime Engineering, 2009
The UK government has committed to a reduction of carbon dioxide emissions for England and Wales ... more The UK government has committed to a reduction of carbon dioxide emissions for England and Wales by 20% below 1990 levels by 2010 and to increase the amount of electrical energy generated by renewable energy sources to 10% by 2010 and 15% by 2015. Wave and tidal energy are likely to contribute significantly to achieving these targets as important renewable energy technologies for the UK. The south-west region in particular has the potential to generate substantial amounts of renewable energy from its wave and tidal stream resources. The South West of England Regional Development Agency (SWRDA) recognises the potential of the marine energy industry for the region and is supporting demonstration projects in marine energy through the Wave Hub project and the Peninsular Research Institute in Marine Renewable Energy (Primare). The Wave Hub project provides a unique opportunity for interdisciplinary research to aid developments in marine renewable energy. In this paper, a description of s...
High-quality wind field data are key to improving the accuracy of storm surge simulations in coas... more High-quality wind field data are key to improving the accuracy of storm surge simulations in coastal and estuarine water. These data are also of great significance in studying the dynamic processes in coastal areas and safeguarding human engineering structures. A directional correction method for ECMWF reanalysis wind data was proposed in this paper based on the correlation with the measured wind speed and direction. The results show that the accuracies of wind speed and direction were improved after being modified by the correction method proposed in this paper. The modified wind data were applied to drive the storm surge model of the Yangtze Estuary for typhoon events, which resulted in a significant improvement to the accuracy of hindcasted water levels. The error of the hindcasted highest water levels was reduced by 16–19 cm.
Predicting the meso-scale morphological evolution of our shorelines remains a major challenge for... more Predicting the meso-scale morphological evolution of our shorelines remains a major challenge for coastal management. The main aim of this paper is to use long-term coastal monitoring data of beach profile elevations within the Suffolk coast (east coast of the United Kingdom) to investigate meso-scale linkages between physical processes and coastal response. Patterns of beach behaviour are investigated using Empirical Orthogonal Function (EOF) and links between wave climate and beach response are explored through Canonical Correlation Analysis (CCA). The datasets consist of detailed nearshore wave measurements and profile surveys of the coastal frontage covering a period of over 22 years. The structure of the datasets and the data handling methods are described. Some results and interpretation of the analyses are presented. In particular we find a strong correlation between the first temporal eigenfunction of beach profiles and the trend in beach volume at three sites with very diff...
Due to the strong nonlinear interaction with river discharge, tides in estuaries are characterise... more Due to the strong nonlinear interaction with river discharge, tides in estuaries are characterised as nonstationary and their mechanisms are yet to be fully understood. It remains highly challenging to accurately predict estuarine water levels. Machine learning methods, which offer a unique ability to simulate the unknown relationships between variables, have been increasingly used in a large number of research areas. This study applies the LightGBM model to predicting the water levels along the lower reach of the Columbia River. The model inputs consist of the discharges from two upstream rivers (Columbia and Willamette Rivers) and the tide characteristics, including the tide range at the estuary mouth (Astoria) and tide constituents. The model is optimized with the selected parameters. The results show that the LightGBM model can achieve high prediction accuracy, with the root-mean-square-error values of water level being reduced to 0.14 m and the correlation coefficient and skill...
Water transparency, measured with Secchi disk depth (SDD), is an important parameter for describi... more Water transparency, measured with Secchi disk depth (SDD), is an important parameter for describing the optical properties of a water body. This study evaluates variations of SDD and related impact factors in the Bohai and Yellow Seas (BYS). Based on a new mechanistic model proposed by Lee et al. (2015) applied to MODIS remote sensing reflectance data, climatological SDD variation from 2003 to 2019 was estimated. The annual mean images showed an increasing trend from the coastal zone to the deep ocean. Lower values were found in the Bohai Sea (BHS), while higher values observed in the center of the southern Yellow Sea (SYS). Additionally, the entire sea has shown a decreasing temporal tend, with the variation rate lowest in the BHS at 0.003 m y−1, and highest in the SYS at 0.015 m y−1. However, the weak increasing trend that appeared since 2017 suggests that water quality seems to have improved. Further, it displayed seasonal patterns of low in winter and spring and high in summer a...
A water-retaining curtain (WRC) has become a useful facility in selective withdrawal and sediment... more A water-retaining curtain (WRC) has become a useful facility in selective withdrawal and sedimentation control, but the force analysis of a curved curtain is still lacking. Based on flume experimental tests and numerical simulations, this paper analyzes the variation laws of pressure difference and thrust of WRC. The results show that under the uniform inflow condition, the distribution of pressure difference on the WRC is relatively even, and the maximum value is located at the upper part of the curtain. When arc length–height ratio increases, the location of maximum pressure difference gets lower. In addition, the variation law of thrust of WRC conforms to the classical resistance equation. The drag coefficient is found to fit a power function of the water-retaining ratio, a second-degree polynomial function of arc length–height ratio, and linear function of inclination ratio. The results also yield a simplified forecasting formula of thrust of WRC which is proposed and verified u...
Journal of Atmospheric and Oceanic Technology, 2019
Influenced by river discharge, the tidal properties of estuarine tides can be more complex than t... more Influenced by river discharge, the tidal properties of estuarine tides can be more complex than those of oceanic tides, which makes the tidal prediction less accurate when using a classical tidal harmonic analysis approach, such as the T_TIDE model. Although the nonstationary tidal harmonic analysis model NS_TIDE can improve the accuracy for the analysis of tides in a river-dominated estuary, it becomes less satisfactory when applying the NS_TIDE model to a mesotidal estuary like the Yangtze estuary. Through the error source analysis, it is found that the main errors originate from the low frequency of tidal fluctuation. The NS_TIDE model is then modified by replacing the stage model with the frequency-expanded tidal–fluvial model so that more subtidal constituents, especially the “atmospheric tides,” can be taken into account. The results show that the residuals from tidal harmonic analysis are significantly reduced by using the modified NS_TIDE model, with the yearly root-mean-squ...
In this paper, results of sediment transport at Exe Estuary, Devon, UK, obtained from a process-b... more In this paper, results of sediment transport at Exe Estuary, Devon, UK, obtained from a process-based model under a number of wave and tide scenarios, are presented. This study uses a nested modelling system, which consists of an oceanic scale wave model WAM and a tide/surge model POLCOMS, to transform the meteorological information to nearshore wave and tide conditions for a fine resolution local coastal process-based model to carry out detailed predictions of nearshore hydrodynamics and morphodynamics at the study area. The work is focused on studying the impacts of yearly and 1 in 50 year return period storm events on morphology at the mouth of the Exe Estuary and the adjacent coasts. Comparisons of model results are made with the beach survey data carried out by the local authorities in March 2008, in addition to the model tests on both yearly calm and storm conditions in November 2006.
In this paper, we show how the methodology based on the Source-Pathway-Receptor-Consequence (SPRC... more In this paper, we show how the methodology based on the Source-Pathway-Receptor-Consequence (SPRC) approach can be used to identify the risks of flooding and erosion. The methodology is applied to the Teign Estuary in Devon, UK to define the linkages between physical loads (waves, tides), sea defences, areas liable to flooding and the impacts of flooding.
Proceedings of the ICE - Maritime Engineering, 2009
The UK government has committed to a reduction of carbon dioxide emissions for England and Wales ... more The UK government has committed to a reduction of carbon dioxide emissions for England and Wales by 20% below 1990 levels by 2010 and to increase the amount of electrical energy generated by renewable energy sources to 10% by 2010 and 15% by 2015. Wave and tidal energy are likely to contribute significantly to achieving these targets as important renewable energy technologies for the UK. The south-west region in particular has the potential to generate substantial amounts of renewable energy from its wave and tidal stream resources. The South West of England Regional Development Agency (SWRDA) recognises the potential of the marine energy industry for the region and is supporting demonstration projects in marine energy through the Wave Hub project and the Peninsular Research Institute in Marine Renewable Energy (Primare). The Wave Hub project provides a unique opportunity for interdisciplinary research to aid developments in marine renewable energy. In this paper, a description of s...
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