In recent years, there has been growing concern about the impact of diffuse source pollution on water bodies, particularly due to associated health risks. Coastal waters can receive considerable inputs of pollutants f...In recent years, there has been growing concern about the impact of diffuse source pollution on water bodies, particularly due to associated health risks. Coastal waters can receive considerable inputs of pollutants from catchments since they serve as sinks for many diffuse pollutants. Furthermore, bathing waters have in the recent past often failed to comply with the various standards set by different bathing water directives. The Severn estuary has recently attracted a lot of attention in terms of bathing water compliance due to its potential to generate a considerable amount of renewable energy for the UK. It is against this background that a physical model of the estuary has been set up in the Hydraulics Laboratory at Cardiff University, for studies to be undertaken to mimic the conditions of the prototype. A sandbox filled with non-cohesive sediments within the laboratory has been set up to investigate the behaviour of pollutants in propagating from the idealised groundwater environment into the estuarine waters. It has been demonstrated that for a semi-diurnal tidal estuary like the Severn, tides have a lesser effect on the transport of solutes than flows from the catchments. Thus the impact of pollution from diffuse sources to marine environments from catchments could be higher in less tidally dominated coastal waters than a tidal one.展开更多
Details are given herein of the current main proposals for tidal energy provision from the Severn Estuary, in the UK, with particular emphasis being focused on the Severn Barrage project, as originally promoted by the...Details are given herein of the current main proposals for tidal energy provision from the Severn Estuary, in the UK, with particular emphasis being focused on the Severn Barrage project, as originally promoted by the Severn Tidal Power Group. In particular, emphasis has focused on assessing the potential hydro-environmental impacts and power outputs of a barrage across the estuary, with an unstructured grid, high resolution, model being developed and applied to the estuary to assess the implications of each of five shortlisted proposed schemes on the hydrodynamic, geomorphologic, flood risk and faecal indicator organism changes within the estuary. An outline is given of recent research on power refinements to the model to assess the options for power generation. The results show that the Severn Barrage has the potential to reduce the tidal currents in a highly dynamic estuary. This leads to the reduction of suspended sediment loads (particularly upstream of the barrage), an increase of light penetration within the water column and, potentially, an increase in the benthic bio-diversity and the level of aquatic life in the estuary. The results also show that the Severn Barrage will reduce markedly the risk of flooding upstream of the barrage and to a lesser extent downstream of the structure. In contrast the alternative options have far less impact on flood risk changes. In addition to the Severn Barrage some results are shown herein for a typical lagoon option, namely the Fleming Lagoon.展开更多
In this study, emphasis has focused on assessing the potential hydro-environmental impacts of a barrage across the Severn Estuary, with a numerical model being developed and applied to the estuary to assess the impact...In this study, emphasis has focused on assessing the potential hydro-environmental impacts of a barrage across the Severn Estuary, with a numerical model being developed and applied to the estuary to assess the impacts of proposed Severn Barrage on the hydrodynamic, sediment transport and faecal indicator organism distribu- tion within the estuary. The results show that the Severn Barrage has the potential to reduce the tidal currents in a highly dynamic estuary. This leads to the reduction of suspended sediment concentrations, which in turn affects the bacterial transport processes which is highly related to the sediment transport processes.展开更多
The Severn Estuary has one of the largest tidal ranges in the world and has long been the subject of consideration for tidal energy generation.Whilst plans to build a tidal barrage across the estuary have existed in v...The Severn Estuary has one of the largest tidal ranges in the world and has long been the subject of consideration for tidal energy generation.Whilst plans to build a tidal barrage across the estuary have existed in various forms since the 1920s,the 1989Severn Tidal Power Group(STPG)proposal is commonly referred to as the original Severn Barrage.The UK government abandoned this ebb generation scheme as a public investment project in 2010.However,plans to build a two-way generation scheme were more recently put forward by a private consortium,namely Hafren Power.To assess the impact that a barrage would have on the hydro-environment in the estuary a number of numerical modelling studies have previously been conducted for the STPG scheme.As this design has now been superseded by the Hafren Power proposal,new studies have been conducted to investigate the impact of a two-way scheme.In this study the hydro-environmental impacts of both ebb-only and two-way schemes were assessed using physical and numerical modelling techniques.Scale model barrages were constructed and testing was carried out using a physical model of the Severn Estuary,located in the hydraulics laboratory at Cardiff University.A depth integrated numerical model,namely DIVAST,was applied to the physical model geometry and modifications were made to simulate the effects of the barrage structures.The numerical model predictions showed good agreement with the corresponding laboratory data.The results were consistent with conclusions from previous studies,relating to the ebb-only scheme.These included an increase in the minimum water levels upstream of the barrage,a reduction in the mean water levels downstream of the barrage and a general reduction in tidal velocities.For a two-way scheme changes in the tidal elevations and velocities depended on the exact operating conditions of the barrage.It was found that with no starting head the tidal regime was similar to the natural state,with little change in the elevations and a slight reduction in the mean velocities.As a starting head was introduced there was still little change in elevations downstream of the barrage,however,there was an increase in the minimum water levels upstream of the barrage,and a further reduction in the mean velocities.展开更多
文摘In recent years, there has been growing concern about the impact of diffuse source pollution on water bodies, particularly due to associated health risks. Coastal waters can receive considerable inputs of pollutants from catchments since they serve as sinks for many diffuse pollutants. Furthermore, bathing waters have in the recent past often failed to comply with the various standards set by different bathing water directives. The Severn estuary has recently attracted a lot of attention in terms of bathing water compliance due to its potential to generate a considerable amount of renewable energy for the UK. It is against this background that a physical model of the estuary has been set up in the Hydraulics Laboratory at Cardiff University, for studies to be undertaken to mimic the conditions of the prototype. A sandbox filled with non-cohesive sediments within the laboratory has been set up to investigate the behaviour of pollutants in propagating from the idealised groundwater environment into the estuarine waters. It has been demonstrated that for a semi-diurnal tidal estuary like the Severn, tides have a lesser effect on the transport of solutes than flows from the catchments. Thus the impact of pollution from diffuse sources to marine environments from catchments could be higher in less tidally dominated coastal waters than a tidal one.
基金Supported by the Flood Risk Management Research Consortium (PhaseⅡ)the UK Engineering and Physical Sciences Research Council (GR/S76304)the Welsh Assembly Government European Regional Development Fund, Project HE09
文摘Details are given herein of the current main proposals for tidal energy provision from the Severn Estuary, in the UK, with particular emphasis being focused on the Severn Barrage project, as originally promoted by the Severn Tidal Power Group. In particular, emphasis has focused on assessing the potential hydro-environmental impacts and power outputs of a barrage across the estuary, with an unstructured grid, high resolution, model being developed and applied to the estuary to assess the implications of each of five shortlisted proposed schemes on the hydrodynamic, geomorphologic, flood risk and faecal indicator organism changes within the estuary. An outline is given of recent research on power refinements to the model to assess the options for power generation. The results show that the Severn Barrage has the potential to reduce the tidal currents in a highly dynamic estuary. This leads to the reduction of suspended sediment loads (particularly upstream of the barrage), an increase of light penetration within the water column and, potentially, an increase in the benthic bio-diversity and the level of aquatic life in the estuary. The results also show that the Severn Barrage will reduce markedly the risk of flooding upstream of the barrage and to a lesser extent downstream of the structure. In contrast the alternative options have far less impact on flood risk changes. In addition to the Severn Barrage some results are shown herein for a typical lagoon option, namely the Fleming Lagoon.
文摘In this study, emphasis has focused on assessing the potential hydro-environmental impacts of a barrage across the Severn Estuary, with a numerical model being developed and applied to the estuary to assess the impacts of proposed Severn Barrage on the hydrodynamic, sediment transport and faecal indicator organism distribu- tion within the estuary. The results show that the Severn Barrage has the potential to reduce the tidal currents in a highly dynamic estuary. This leads to the reduction of suspended sediment concentrations, which in turn affects the bacterial transport processes which is highly related to the sediment transport processes.
基金supported by the LCRI projectpart funded by the Welsh Government+2 种基金the Higher Education Funding Council for Walesthe Welsh European Funding Officethe European Regional Development Fund (ERDF) Convergence Programme
文摘The Severn Estuary has one of the largest tidal ranges in the world and has long been the subject of consideration for tidal energy generation.Whilst plans to build a tidal barrage across the estuary have existed in various forms since the 1920s,the 1989Severn Tidal Power Group(STPG)proposal is commonly referred to as the original Severn Barrage.The UK government abandoned this ebb generation scheme as a public investment project in 2010.However,plans to build a two-way generation scheme were more recently put forward by a private consortium,namely Hafren Power.To assess the impact that a barrage would have on the hydro-environment in the estuary a number of numerical modelling studies have previously been conducted for the STPG scheme.As this design has now been superseded by the Hafren Power proposal,new studies have been conducted to investigate the impact of a two-way scheme.In this study the hydro-environmental impacts of both ebb-only and two-way schemes were assessed using physical and numerical modelling techniques.Scale model barrages were constructed and testing was carried out using a physical model of the Severn Estuary,located in the hydraulics laboratory at Cardiff University.A depth integrated numerical model,namely DIVAST,was applied to the physical model geometry and modifications were made to simulate the effects of the barrage structures.The numerical model predictions showed good agreement with the corresponding laboratory data.The results were consistent with conclusions from previous studies,relating to the ebb-only scheme.These included an increase in the minimum water levels upstream of the barrage,a reduction in the mean water levels downstream of the barrage and a general reduction in tidal velocities.For a two-way scheme changes in the tidal elevations and velocities depended on the exact operating conditions of the barrage.It was found that with no starting head the tidal regime was similar to the natural state,with little change in the elevations and a slight reduction in the mean velocities.As a starting head was introduced there was still little change in elevations downstream of the barrage,however,there was an increase in the minimum water levels upstream of the barrage,and a further reduction in the mean velocities.
