Macroinvertebrate richness on flood defence walls of the tidal River Thames

2011 ◽  
Vol 15 (2) ◽  
pp. 327-346 ◽  
Author(s):  
Simon P. G. Hoggart ◽  
Robert A. Francis ◽  
Michael A. Chadwick

Following upon the severe flooding from an exceptional tide cum surge in February 1953 a removable flood barrier in Long Reach was considered as the basis of a flood defence system compatible with the navigation interests yet avoiding the high cost of bank raising in the metropolis. Three designs of barrier were developed and costed, each embodying two 150 m wide navigation openings. The preferred system incorporated drop gates supported on high towers above shipping when not in use. The navigation authorities ruled that an unobstructed opening at 425 m was necessary and a new design exercise found in favour of retractable barrier structures but at increased cost with less reliability in performance. The formation of the Greater London Council led to a wider investigation of possible barrier sites and the lesser use by shipping of reaches above the Royal Docks permitted narrower openings. Schemes for some six different sites and over 40 variations in span arrangement were investigated and led to a proposal for four 60 m navigation openings in Woolwich Reach which might be closed by a form of rising section gate. This has proved to be the cheapest, most reliable and quickest to install of all the schemes investigated and is now the basis of design for contract.


2011 ◽  
Vol 63 (1) ◽  
pp. 80-87 ◽  
Author(s):  
G. B. Thomas ◽  
D. Crawford

It takes a few millimetres of rainfall to cause the 34 most polluting combined sewer overflows (CSOs) to discharge into the River Thames. Currently, in a typical year, spillages to the tidal reaches of the River Thames occur about 60 times, with an estimated spill volume of 39 million cubic metres. Both the UK Government and the European Union have determined that the CSO discharges have an adverse environmental impact on fish species, introduce unacceptable aesthetics and elevate the health risks for recreational users of the Thames, with a frequency of discharge which is in breach of the Urban Wastewater Treatment Directive. Studies have established that the environmental objectives can be fully met on the most cost-effective basis by completing both quality improvements to treatment works and by the provision of a storage and transfer tunnel to intercept unsatisfactory CSOs. Extensive modelling has been undertaken to develop an optimised solution. In parallel with the design development a rigorous and comprehensive site selection methodology has been established to select sites and consult stakeholders and the public on the preferred sites and scheme, with the first stage of public consultation planned for later in 2010. The London Tideway Tunnels are an essential part of the delivery of improvements to the water quality of the tidal River Thames, and this ambitious, historic scheme represents a vital strategic investment in London’s infrastructure.


1984 ◽  
Vol 16 (5-7) ◽  
pp. 139-154 ◽  
Author(s):  
Ching-Gung Wen ◽  
Jao-Fuan Kao ◽  
Lawrence K Wang ◽  
Chii Cherng Liaw

A practical method of determining reaeration coefficients would greatly aid design engineers in determining the degree of wastewater treatment required for a proposed effluent discharge. Many previous tidal river and estuary studies emphasized mainly the effects of flow conditions (such as velocity, water depth, turbulent intensity, hydraulic gradient, etc.) and temperature on stream aeration, and the effect of salts was not seriously considered. In this research a new mathematical model of reaeration coefficient considering the effect of salts has been developed for water quality analysis in tidal rivers and estuaries. The reaeration coefficient in saline water, k2s(day−1, base e) at any chloride concentration C(g/l) and at 20°C, can be expressed byin which k2f is the reaeration coefficient in fresh water at 20°C. The correlation coefficient of k2s/k2f and C is 0.88.


1993 ◽  
Vol 27 (3-4) ◽  
pp. 311-314 ◽  
Author(s):  
Aaron B. Margolin ◽  
Charles P. Gerba ◽  
Kenneth J. Richardson ◽  
Jaime E. Naranjo

Nucleic acid hybridization provides a rapid non-cell culture method for the detection of enteric viruses in water. The purpose of this work was to compare the detection of naturally occurring enteroviruses by cell culture with their detection by a poliovirus gene probe in various types of water samples. Samples of activated sludge effluent, tertiary treated wastewater (activated sludge, filtration and passage through reverse osmosis), ground water, surface water and tidal river water were processed through 1 MDS Virozorb filters to concentrate any naturally occurring virus. Viruses were eluted from the filters with pH 9.5 beef extract and reduced in volume by flocculation to 20-30 ml. These concentrates were then assayed in the BGM cell line by the cytopathogenic effects (CPE) method and by a poliovirus cDNA probe (base pairs 115-7440) labeled with 32P. A total of 233 samples were assayed in this manner. In slightly more than 93% of the samples gene probe and cell culture yielded the same results. Of these samples 36 were positive by gene probe and 28 by cell culture assay. Positive samples for gene probe were confirmed by treatment with NaOH or RNAse and then reprobed. Samples demonstrating CPE upon primary passage were confirmed positive by subsequent passage of cell lysate on a new monolayer of BGM cells. Ten samples were positive by gene probe and negative by cell culture, and 4 samples were negative by gene probe and positive by cell culture.


1998 ◽  
Vol 38 (6) ◽  
pp. 327-335
Author(s):  
Yasunori Kozuki ◽  
Yoshihiko Hosoi ◽  
Hitoshi Murakami ◽  
Katuhiro Kawamoto

In order to clarify the origin and behavior of suspended particulate matter (SPM) in a tidal river, variation of SPM in a tidal river was investigated with regard to its size and constituents. SPM was separated into three groups according to size. Change of contents of titanium and organic substances of each group of SPM was examined. SPM which was discharged by run-off was transported with decomposition and sedimentation in a tidal river. Concentration of SPM with a particle size greater than 0.45 μm increased due to resuspension in a tidal river. Origin of SPM with a size of less than 0.45 μm at upstream areas was from natural soil and most of such SPM which had been transported settled near a river mouth. It was determined from examination of the CN ratio and the ratio of the number of attached bacteria to free bacteria that SPM with a size greater than 1.0 μm at upstream areas was decomposing intensively. At the downstream areas, SPM with a size of less than 0.45 μm came from the sea. SPM with particle size greater than 1.0 μm consisted of plankton and substances which were decomposed sufficiently while flowing.


2021 ◽  
Vol 32 ◽  
pp. 100289
Author(s):  
Thomas van der Pol ◽  
Jochen Hinkel ◽  
Jan Merkens ◽  
Leigh MacPherson ◽  
Athanasios T. Vafeidis ◽  
...  

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