The Use of Different Conveyance Calculations for Modelling Flows in a Compact Compound Channel

Flow measurements have been taken for steady and unsteady flows on a reach of a river having a compact compound channel. The 'single channel', 'divided channel' and 'lateral' distribution methods have been used to calculate conveyances for use in a one-dimensional unsteady flow model of the reach. Comparisons with measured flows show that the divided channel method and the lateral distribution method both underestimate floodplain flow depths. The lateral distribution method gives the closest accuracy in the relative depth range 0.15 ≤ Yr < 0.40. For large flow depths the single channel method becomes more accurate and slightly over-estimates flow depths.
The accuracy of unit width discharge distributions, calculated from the lateral distribution method are assessed by comparison with observed distributions for overbank flows.     

Strategic Resource Development Options in England and Wales

This paper describes the options which had to be considered for new water resources in the development of the † National Rivers Authority's water resource strategy for England and Wales. The options included interregional transfers, strategic reservoirs, and a range of unconventional schemes including aquifer recharge, effluent re-use, groundwater abstraction where levels are rising, desalination, and transfer by sea. The main options are described and comparative costs are presented.     

Effect of semi-rigid connections on steel column strength

A review has been made of all available experimental data relating to the moment versus in-plane rotational behaviour of practical beam-to-column connection types as used in steel frames. This has clearly shown that all forms of connection possess some stiffness which will act as partial restraint to the column's ends. Moreover this restraint has been found to be a non-linear function of connection deformation. Methods of mathematically describing connection data have been reviewed and an improved representation based on the use of cubic B-splines proposed. This possesses the advantage that it will not give an (incorrect) negative connection stiffness. Using this technique to model connection behaviour a computer program for the maximum strength analysis of steel columns has been written. This is based on a Newton-Raphson incremental finite element approach and incorporates features such as initial lack of straightness and spread of yield through the cross-section including the effects of residual stresses. The results of some preliminary analyses, which demonstrate the increases in column strength and reduction in column deformation that result from a consideration of actual joint behaviour, are presented.     

Abbeystead Outfall Works: Background to Repairs and Modifications – and Lessons Learned

The explosion at the Abbeystead valve house in May 1984, with its attendant loss of life and injury, forcibly drew the attention of the public to the dangers of methane and other natural gases. It also reaffirmed to the water industry and engineering professions the pervasive nature of the gas and the need to take appropriate measures in the construction, design and operation of any scheme which involves a possible methane presence. The investigations into the source and mechanism of the methane gas ingress, and the design of the permanent repairs and modifications to the scheme, have illustrated many of the risks and problems associated with methane and the measures for dealing with them.
The paper describes the essential repairs and modifications which had to be carried out, the main lessons learned, and the recommendations which are felt to be applicable to new and existing water schemes where methane may be present.     

Reconstruction of British Nuclear Fuel's Drigg Marine Outfall

In 1985 the House of Commons Environment Committee expressed reservations over some of the waste-management procedures followed by British Nuclear Fuels Ltd at their Drigg low-level radioactive waste disposal facility near Sellafield in Cumbria. These reservations prompted the company to implement a £20 million programme of improvements aimed at maximizing site usage, reducing trench leachate arisings and redirecting to the Irish Sea.
This paper provides information and test results associated with design considerations and initial dilution testing, respectively, of a computercontrolled long sea outfall system designed to discharge leachate to the Irish Sea. Information is also provided on difficulties experienced during construction of the outfall.     

A Methodology for Monitoring the Performance of Combined Sewer Overflows

The authors have been involved with the field monitoring of combined sewer overflows and screens over a number of years. During this period they have developed a monitoring methodology which ensures reliability, consistency and accuracy of results. The paper recommends appropriate equipment to be used for monitoring the qualitative and quantitative performance of combined sewer overflows and gives recommendations on location and installation thereof. Particular reference is made to methods for cross-correlating data amongst monitors and for proper interpretation of the results. The recommended methods have been proven in the field on a variety of working project.     

KNOWLEDGE-BASED SYSTEM ON WATER-RESOURCE MANAGEMENT IN COASTAL WATERS

Computers which are used conventionally in numerical models for problem-solving and fast number-crunching are not user-friendly and lack knowledge transfer in model interpretation. Recent advances in artificial intelligence make it possible to systemise the experience and decision-making procedures of human experts. This paper describes the development of a prototype knowledge-based system (an advanced technique of artificial intelligence) as a knowledge-transfer tool for water-resource planning and management in coastal waters. The system can (a) run on a desktop computer and (b) act as a design aid, to assist in numerical modelling to simulate flow and/or water quality. Using the application in Hong Kong coastal waters, it was verified that the prototype system had the capability to undertake the reasoning process to select the model and associated parameters, equivalent to a human expert.     

The strength and deformation characteristics of high early strength structural concrete

There are many possible structural applications of concrete with a compressive strength of about 100 N/mm². In practice, however, the development of early strength is far more important, but the combination of both can bring considerable economic benefits to the construction industry. Tests are reported on the strength and deformation characteristics of high early strength structural concrete. Tests using an ultra fine cement with expanded slate lightweight aggregate and granite produced concretes with a strength of 30–40 N/mm² and 60–70 N/mm² respectively in 24 hours. Tests with aluminous cement produced better aggregate-matrix bond and developed strengths of about 95 N/mm² in the same time. Equations are presented to predict the tensile strength and elasticity of the high early strength concrete. It is shown that the rapid hydration results in a high rate of shrinkage and creep initially but the long-term deformation characteristics are comparable to normal concrete. It is suggested that it is worth exploring methods to minimise the effects of conversion.     

Behaviour of concrete subjected to passive confinement

This paper is concerned with an experimental investigation of the behaviour of confined concrete. The behaviour of concrete under passive confinement is established by testing concrete specimens confined by steel tubes, then compared with that established in previous tests for concrete under active confinement provided hydraulically. Behaviour is found to be significantly dependent on the method used to provide confinement and the paper describes an attempt to identify the causes of this dependency.