bluuebunny/crossref_metadata_2025 huggingface dataset:
A Solution to the Aral Sea Crisis? Sustainable Water Use in Central Asia
Authors: Hannan T.
Published: July 2007

The Aral Sea is perhaps the most well known of environmental disasters which has resulted from non‐sustainable development. As the sea continues to decline, a search is maintained for a means of achieving sustainability within the context of national economies which are new and fragile, and where international tensions over water are a major factor in the Central Asian political picture. Using the Karakum Main Canal of Turkmenistan as an example of the Aral Sea irrigation projects which commenced during the 1950s, the paper explores the effects of non‐sustainability and poor water management with the luxury of hindsight in order to draw lessons for the future. It presents the proposals aimed at future sustainability for the Karakum Canal and explores whether achieving sustainability is now possible and practical in the current regional and global political atmosphere.
Contingent Valuation of First‐Time Sewerage Provision in South‐East England
Authors: McMahon P. , Moran D. , Sutherland P. , Simmonds C.
Published: July 2007

Section 101A of the Water Industry Act 1991 requires that sewerage undertakers provide a public sewer to replace private wastewater systems if certain conditions are met. These include identification of pollution and amenity problems attributable to the private systems and economic justification of public sewer provision. Economic justification necessitates that the costs and the benefits of public sewer provision are compared. An environmental valuation study, using the contingent valuation method, has been carried out in three locations in south‐east England to provide the average monetary value of the benefits accruing to households with unsatisfactory private systems. A statistical analysis of the survey‐response data has yielded a monetary value which can be used in the assessment of the benefits of first‐time public sewerage schemes.
Some Hydrogeological Peculiar to Various Types of Problems Small Islands
Authors: Robins N. S. , Lawrence A. R.
Published: July 2007

There are many problems associated with the investigation of small island hydrogeology, including (i) the availability of data and the distribution of both spatial and temporal data sets, (ii) the dynamics of the groundwater to sea‐water interface and the shape of the so‐called groundwater lens, and (iii) the difficulties of evaluating recharge to groundwater and of calculating the volume of groundwater discharge to the sea. These issues are compounded by (a) the ratio of coast to area in small islands, (b) the problems of extreme topography, and (c) the identification of baseflow to rivers and streams. A simple classification of island types assists in evaluating hydro‐geological regimes, and the importance of groundwater in an island context cannot be over‐emphasised.
Easter 1998 Floods
Authors: Horner M. W. , Walsh P. D.
Published: July 2007

Prior to Easter 1998, the 1947 floods were the reference events for flood‐risk management in many catchments throughout England and Wales. However, Easter flood levels were generally higher than those of 1947 in the river systems draining an area of about 5000 km2, bounded by Bedford in the east, Evesham in the west, Peterborough in the north, and Oxford in the south.

The paper describes the background to the floods and the independent review, and outlines the lessons which emerged from the Easter 1998 flood experiences, particularly in relation to flood‐plain management, hydrometry and flood forecasting and warning.
Evaluation of a Pilot‐Scale Bioscrubber for the Removal of Hydrogen Sulphide
Authors: Koe L. C. C. , Yang F.
Published: July 2007

This technical note describes an investigation on the feasibility of using treated wastewater to support the operation of a fixed‐film bioscrubber for H2S removal. A laboratory‐scale fixed‐film bioscrubber was assembled using Thiobacillus bacteria which were isolated from a sample of raw sludge, cultured in the laboratory, and immobilised onto the scrubber's plastic packing media by an immersion method.
Flow Requirements of Spawning Atlantic Salmon in an Upland Stream: Implications for Water‐Resource Management
Authors: Webb J. H. , Gibbins C. N. , Moir H. , Soulsby C.
Published: July 2007

The spawning sites selected by female Atlantic salmon (Salmo salar) were surveyed over three consecutive years in the Girnock Burn, Aberdeenshire, Scotland. Discharge was calculated for each spawning site to assess within‐catchment variation in spawning discharge selection. In total, 428 incidents of female spawning activity were logged at 48 sites. Fish selected relatively high flows in which to spawn, with the lowest utilised discharge being equivalent to the burn's 50 percentile flow.

The results emphasise the importance of relatively high flows during the spawning season and, more specifically, a range of flows which ensures that sites are distributed as widely as possible and are accessible and suitable.
Environmental Performance Indicators: The Water Industry of England and Wales
Authors: Johnston A. , Smith A.
Published: July 2007

Water companies in England and Wales produce reports using environmental performance indicators which have been developed in‐house. However, there is no recognised methodology for the development of these indicators, and an analysis of available guidance led to the proposal of an appropriate model. This model was tested by semi‐structured interviews of water‐company managers, and a questionnaire was completed by managers from other industries. The responses from the interviews supported the inclusive, quality‐driven approach advocated by the model, and indicated a need to examine (a) the style of management, (b) the staffing structure in water companies, (c) the connection between environmental management systems and indicator development, (d) types of objectives and targets, and (e) the use of indicators as public‐relations tools. The result is a methodology for indicator development which can be applied by managers in industry.
Potential Endocrine Disrupting Substances from Materials in Contact with Drinking Water
Authors: Fawell J. K. , Chipman J. K.
Published: July 2007

At present, there is much interest in the potential effects of chemicals on the endocrine systems in animals and man. Chemicals with endocrine‐disrupting potential include (a) various phthalates, (b) compounds based on bisphenol A and F, (c) compounds based on alkyl phenols, and (d) the antioxidant butylated hydroxyanisole. However, the potency of these chemicals in comparison with natural hormones appears to be very low. Although there is some evidence for activity in animals, high doses are usually necessary, and there is controversy and uncertainty in the interpretation of some positive findings. In addition to consideration of potential hazards, the level of exposure through leaching of these chemicals into drinking water is an important component of risk assessment. The present approval processes ensure that such exposure is very low. The paper suggests a strategy for the future continued assurance of an adequate safety margin for human exposure to such substances through drinking water.
The Impact of the Water Framework Directive on Catchment‐ Management Planning in the British Isles (Abridged)
Authors: Williams K.
Published: July 2007

The water framework Directive is proposed as a mechanism for applying river‐basin management across the European Union. Proposals for River‐Basin Management Plans might have an impact on the present system of Local Environment Agency Plans and on schemes which are used in the British Isles to provide river management on a catchment basis. For this study, representatives from the Environment Agency, Scottish Environmental Protection Agency and European Parliament advisors were interviewed. In addition, Local Environment Agency Plans were assessed for compatibility with the requirements of River‐Basin Management Plans.
The Sea‐Defence Value of Salt Marshes: Field Evidence From North Norfolk
Authors: BA I. Möller , Spencer T. , French J. R. , Leggett D. J. , Dixon M.
Published: July 2007

Approaches to coastal management have focused increasingly on ‘soft’engineering methods such as beach/foreshore recharge or the managed realignment of coastal defences. In this context, the creation/maintenance of salt marshes is often seen as being of ecological and flood‐defence importance. However, until recently, no field data of wave attenuation over Northern European salt marshes had been available; therefore the debate on the sea‐defence value of salt marshes has remained highly speculative. This paper (a) reviews results from a field and numerical modelling study at Stiffkey, north Norfolk, (b) presents a scientifically based argument for the evaluation of salt marshes as part of sea‐defence schemes, and (c) discusses the relationship between hydrodynamic parameters, salt‐marsh surface characteristics, and possible management implications and engineering guidelines.
Upgrading a Conventional Activated‐Sludge Plant Using a Multi‐Stage Aerobic System with Step Sludge Recirculation
Authors: Palma L. Di , Eng Dr. , Medici F. , Eng Dr.
Published: July 2007

The performance of a multi‐stage activated‐sludge plant with partial biomass recirculation was examined. The system, which was designed to treat domestic sewage, consists of four stages and has two recirculation flows: (a) directly into the anoxic stage, and (b) distributed over all the aerobic stages from the secondary settlement tank. Different values of recirculation flow to each aerobic stage were adopted during the experiments, and the optimal configuration for removing both ammoniaca! nitrogen and carbonaceous substrate was determined. The configuration which gave the best performance also improved the sludge settleability.
Constructed Wetlands for the Treatment of Runoff from the Newbury Bypass
Authors: Pontier H. , May E. , Williams J. B.
Published: July 2007

The A34 Newbury bypass crosses sensitive watercourses and incorporates runoff‐control systems. The series of treatment stages of each system comprises an oil interceptor, silt trap, grassy slope and constructed wetland. In December 1998, a monitoring programme was initiated for one of the systems to evaluate the removal and behaviour of pollutants, and this paper presents the initial results. Future work will examine the mechanisms involved in metal removal and the fate of other pollutants.
Contractual Issues of Process‐Plant Projects
Authors: CEng G. H. Bateman
Published: July 2007

The paper describes the structure of a process‐plant contract and distinguishes it from other forms of design‐and‐construct contracts. The various tests used in process‐plant contracts are highlighted, including performance tests relating to process guarantees and the remedies for failure to achieve such guarantees, with particular reference to the water industry. The differences between price‐based and cost‐based contracts are reviewed, together with three significant areas of contractor's liabilities for design, defects, and overall contract liability. The paper also briefly introduces the development of operation and maintenance contracts and design‐build‐finance‐operate contracts.
The Control of Nitrite Formation in London's Distribution System
Authors: Williams A. M. , Andrews S. , Wakeford P.
Published: July 2007

The formation of nitrite in distribution systems has been understood for a number of years. This paper explains how controls have been developed based upon that knowledge, and how nitrite formation was reduced by 80% over a period of three years, in London's distribution system. Effective control measures and associated procedures included (a) forming process‐optimisation teams, (b) setting realistic targets, and (c) producing a manageable and simple monitoring system ‐ by training and communication, and using simple analytical equipment. Control measures included optimisation of the ammoniation process and increasing the chlorine concentration in the distribution system.
Integrated Lake and Catchment Phosphorus Model ‐A Eutrophication Management Tool. II: Application to Rutland Water
Authors: Daldorph P. W. G. , Spraggs G. E. , Lees M. J. , Wheater H. S. , Chapra S. C.
Published: July 2007

An integrated lake and catchment model was used to simulate reservoir volume and phosphorus concentrations in Rutland Water over a period of seventeen years, taking into account changes in reservoir output and phosphorus sedimentation resulting from the addition of ferric sulphate. Application of the model for critical‐period analysis and the setting of environmental targets and trigger values are discussed, and an example is given showing the impact of changing reservoir output on the frequency distribution of phosphorus using an eighty‐year set of river‐discharge data. The impact of phosphorus removal at point sources in the catchment on phosphorus concentrations in the river and reservoir is simulated and compared to results from SIMCAT ‐ a steady‐state model which was developed by the Environment Agency. Results are also compared with observed data following the implementation of the EC urban waste water treatment Directive, at the end of 1998.
Integrated Monitoring and Modelling of Odours in Sewerage Systems
Authors: Spooner S. B.
Published: July 2007

The parameters of sewage that affect the production and resulting concentration of hydrogen sulphide in both liquid and gas phases have been monitored in a sewerage system. The data have been used to develop a model of the chemical and physical processes leading to sulphide production in sewers, so that the sources and causes of the problem can be identified. This model has been adapted to predict the concentrations of hydrogen sulphide that can be expected in the sewage and sewer atmosphere, following the construction of a major interceptor tunnel.
Construction Risk in Coastal and River Engineering
Authors: Simm J. D. , Camilleri A. J.
Published: July 2007

New methods and protocols are presented to assess and mitigate time, cost, quality and safety risks in construction, based upon the research behind two manuals which have been produced by HR Wallingford under industry guidance. The paper focuses on the specific risks associated with weather, sea and river state conditions. The inter‐relationship with procurement route and insurance is also discussed. A contractor's view of construction risk is then given in the form of a case study based on the Eastbourne Coast Protection Scheme. This scheme involved work on a coastal foreshore in a tidal and marine environment and included five phases of timber groynes, rock revetments, concrete sea‐walls and the reconstruction of promenades plus two phases of shingle renourishment.
Investment Appraisal in the Water Industry of England and Wales
Authors: Tebbutt R. J. , Guy J. A. , Cochin R. J. , Lester J. N.
Published: July 2007

Since privatisation in 1989, the changing nature of the water industry in England and Wales has increased the need for effective investment appraisal. Previous research highlighted many aspects of the industry that could detract from the efficacy of conventional discounted cash‐flow techniques, and found that an investment‐appraisal technique must fulfil a number of criteria in order to overcome these difficulties. This paper examines a number of financial and strategic management techniques for investment appraisal, and assesses their suitability with reference to these criteria. It shows that, of the studied techniques, the ‘balanced scorecard’appears to be most suited for use in the water industry of England and Wales.
A Biosolids Composting Challenge: Meeting Demand for a Peat‐Free Horticultural‐Grade Product
Authors: Bowman L. , Durham E.
Published: July 2007

In 1996, Thames Water launched a range of peat‐free compost products based on biosolids. In order to keep up with demand and to maintain the high standards of product quality, the company has investigated higher‐rate composting processes and optimisation of the maturation stage. Agitated‐bay composting systems are the preferred in‐vessel technology for large sludge treatment centres using woodchip as a bulking agent. These automated systems (i) accelerate the composting process, (ii) maximise throughput on a smaller footprint, and (iii) achieve better control of odour emissions.

A maturation trial with composted material from the US Filter agitated‐bay system confirmed that a horticultural‐grade product could be attained. Small‐scale maturation trials showed that seeding with mature green waste compost can accelerate nitrification to such a rate that near zero levels of ammonia can be achieved after one month of maturation.
Operating a High‐Rate Digester: The Southern Water Experience
Authors: Brown S. , Sale R.
Published: July 2007

Southern Water has implemented a large capital‐investment programme in order to meet the requirements of the EU Urban Wastewater Treatment Directive. Within Southern Water, the Directive will result in a doubling in the quantity of wastewater sludge to be treated. In order to minimise the amount of sludge to be transported and produce a stabilised sludge which is suitable for recycling to agricultural land, the company's sludge strategy is based on treatment by mesophilic anaerobic digestion.

This paper (a) highlights some of the consequences of operating a high‐rate digestion plant, and (b) focuses on areas such as depositions in thickened sludge digester feed lines, the start‐up procedures for high‐rate digesters, foaming, hair and fibre build‐up problems and treatment failure caused by toxicity inhibition. All these problems have been corrected or controlled and have resulted in Southern Water revising and updating its design manuals and standards, to prevent such future difficulties.
The Rio Salado Basin in Argentina: An Integrated Master Plan
Authors: Palmer J. , Suter S. N. , Aradas R. D.
Published: July 2007

Being close to Buenos Aires and with high production levels in the agriculture sector, the Rio Salado basin is an area which has always attracted investment. During the last century, considerable hydraulic drainage and flood‐alleviation works were carried out to increase agricultural production in the region. However, during the last two decades, the catastrophic effects of flooding and the persistence of low agricultural productivity in most of the area, demonstrate that the interventions (which have been made so far) have been inadequate. Perhaps one of the key factors in the lack of success of historic hydraulic interventions has been the absence of a strategic/ integrated approach. This paper describes the first attempt at integrated river‐basin planning in Argentina.
Groundwater Contamination from Rural Pit Latrines: Examples from Siberia and Kosova
Authors: Banks D. , Karnachuk O. V. , Parnachev V. P. , Holden W. , Frengstad B.
Published: July 2007

New hydrogeochemical data from Kosova and southern Siberia agree with previous studies from Botswana and Moldova in suggesting that high densities of pit latrines (and other domestic pollution sources) in rural villages can result in contamination of potable groundwater supplies by microbes and nitrate. Concentrations in excess of 100 mg/l nitrate have been recorded in each of these areas, at which levels small children may be endangered by methaemoglobinaemia. The sanitation and water‐supply conditions are believed to be typical of large areas of Eastern Europe and the former Soviet Union. It is likely that poor sanitation and conflict with potable‐water supplies are among the main sources of environmental risk to populations in these areas, rather than the industrial and military contamination upon which so many international collaborative programmes have focused.
Environmental Implications of Incineration and Other Advanced Sludge‐Treatment Processes
Authors: Davis R. D. , Glennie E. B. , Hobson J. A. , Sivil D.
Published: July 2007

In the UK, there is a strong trend towards more thermal processing of sludge with energy recovery or advanced treatment of sludge, in preparation for use in agriculture or other outlets. This has resulted from (a) the loss of the sea‐disposal outlet and (b) pressure to improve the microbiological quality of recycled biosolids to land. In 1996–97, incineration accounted for 8% of sludge, and this figure is expected to increase to 21% by the year 2005. During this period, the annual production of sludge is expected to increase from 1.12 million tDS to 1.47 million tDS. More sludge will be treated by processes such as thermal drying, thermophilic digestion, prepasteurisation and mesophilic anaerobic digestion, lime treatment and other advanced options such as gasification. These developments apply across the EU and are likely to be driven forward by the impending revision of the ‘sludge to land’Directive. The paper considers the environmental implications of these developments in terms of energy usage and recovery, air and water quality, greenhouse‐gas emissions, effects on contaminants, and the quality of products or residues.
Maintenance of Sludge‐Treatment Plants
Authors: Thompson M. S.
Published: July 2007

During the last decade, Southern Water has designed, constructed, commissioned and operated a number of large sewage‐treatment works and sludge‐treatment centres. Also, over the last two years, Southern Water Project Delivery has been working closely with Southern Water Operations, to identify and resolve a number of design and operational issues which have arisen at two strategic sludge‐treatment centres, i.e. Canterbury and Goddards Green. The resolution of these issues has been both interesting and technically challenging. The purpose of this paper is to share some of these issues and their resolution.
Developments in Urban Pollution Management
Authors: Clifforde I. , Crabtree B.
Published: July 2007

The paper presents background information about the development of the original edition of the Urban Pollution Management Manual (1994) and gives reasons why the manual was updated relatively soon after initial publication (1998). The latter part of the paper examines three specific issues where the changes between the two editions have proved to be contentious in terms of implementation of the ‘asset management plan 3’programme by the UK water industry, namely: (i) the choice of environmental criteria for protecting river aquatic life; (ii) meeting the requirements for controlling aesthetic pollution; and (iii) the role of simplified modelling in urban pollution management studies. The paper concludes that any increased cost implications for the implementation of the programme are as a result of changes in Environment Agency policy, rather than due to technical changes in procedures.
WATER, SEWERAGE AND DRAINAGE INFRASTRUCTURE FOR PALESTINIAN REFUGEE CAMPS IN LEBANON
Authors: Davey J. C. , Maziliauskas J.
Published: July 2007

Many of the Palestinian refugee camps in Lebanon were originally established as tented encampments during the period 1948–1955. Half a century later, with high population densities and limited vehicular access, they remain largely separate from adjacent Lebanese communities, with infrastructure and welfare services mainly provided by the United Nations. Water supply, sewerage and stormwater‐drainage systems have been developed on a piecemeal basis, are frequently in poor condition, and are inadequate to cops with expanding populations. A project for the design of new systems was commissioned to serve a total population of about 250 000 by the year 2020. The new facilities have had to take account of complex networks of narrow pedestrian alleyways that characterise many of the camps.

This paper provides an insight into (a) working within established refugee camps and other economically poor and densely populated communities, and (b) the problems which were experienced in developing feasible solutions for the improvement of infrastructure.
EFFECTIVE DESIGN OF GAS‐MIXING SYSTEMS FOR THICK SLUDGE DIGESTION: TWO CASE STUDIES
Authors: Cumiskey A. , Harrison D. , Dawson M. , Jolly M.
Published: July 2007

In the UK and elsewhere, advances in the design of anaerobic mesophilic digesters have resulted in a trend towards the digestion of thicker sludges. This includes a number of new facilities using ‘bolt‐on’ technologies such as thermal hydrolysis, pre‐pasteurisation and enzymic hydrolysis. Thermal hydrolysis utilises thickened sludge, and the digester is fed with a high dry‐solids content (typically 12%), thereby intensifying the digestion process and reducing reactor volumes. However, there is limited experience in the design of digester mixing systems for such applications. As the trend continues towards advanced digestion technology, more emphasis will be placed on the basic unit process operation of mixing.

This paper describes the design of a gas‐mixing system for thick feed sludges for two full‐scale plants at Mogden and Aberdeen. Mogden is a refurbishment project and Aberdeen is a newly constructed plant.
A REVIEW OF THE EFFECTS OF SEWER LEAKAGE ON GROUNDWATER QUALITY
Authors: Reynolds J. H. , Barrett M. H.
Published: July 2007

Exfiltration (of sewage into the ground from faults in ageing sewerage networks) has been recognised for many years but has never been quantified. It was considered that this leakage did not pose a groundwater‐contamination threat because it was assumed that pathogens in sewage would either die off or be attenuated before reaching the groundwater level.

This paper identifies why sewers have faults that could allow sewage exfiltration where the sewer is above a groundwater resource. Because of a lack of UK data on sewage exfiltration, research work in Germany is discussed and analogies are made between the sewerage networks of the two countries.

Until recently, it has not been possible to positively identify sewage contamination of groundwater because of other pollutants and potential sources within an urban environment. The development of sewage‐fingerprinting techniques has overcome these difficulties and provides conclusive evidence of sewage contamination of shallow and deep groundwater resources in researched areas. Studies of groundwater recharge and total solute loadings allow quantification of sewage exfiltration reaching the groundwater within the Midlands conurbation. The paper concludes that urban aquifers are potentially more vulnerable to microbiological contamination from leaking sewers than has previously been assumed.
USE OF A FULL‐SCALE TEST FACILITY TO EXAMINE SEWER‐SEDIMENT MOBILITY
Authors: Rushforth P. J. , Tait S. J. , Saul A. J.
Published: July 2007

The mobility of granular in‐sewer sediments was measured in a study which was carried out at the National Combined Sewer Overflow Test Facility, Wigan. It is thought that these measurements are unique in that the facility permits tests using crude sewage and real in‐sewer sediments to be conducted under full‐scale controlled hydraulic conditions. Tests were carried out in which the bedload transport rates, resulting from different steady‐flow discharges and flow depths, were measured. The results were compared with transport‐rate predictions made using relationships which are recommended by the Construction Industry Research and Information Association. These comparisons indicated that, for the sewer sediments, the existing prediction methods are likely to significantly under‐predict the mobility of in‐sewer sediments — particularly if a range of grain sizes is present. This might have important implications both for the design of sewerage systems and for sewer flow quality modelling.
EMPIRICAL FACTORS FOR ESTIMATING OPEN‐WATER EVAPORATION FROM POTENTIAL EVAPORATION
Authors: Finch. J. W.
Published: July 2007

For many years, the standard method for estimating rates of evaporation from open water has been to apply empirical factors to potential evaporation data. However, significant errors can occur through the use of these factors, essentially due to the limitations of the measurements upon which they are based. New empirical factors are presented here for use with the Meteorological Office Rainfall and Evaporation Calculation System for grass potential evaporation and Penman potential evaporation. However, uncertainty in the estimated evaporation rates remains at least 5–12 mm per month.
POTENTIAL GROUNDWATER IMPACTS FROM CIVIL‐ENGINEERING WORKS
Authors: Preene M. , Brassington R.
Published: July 2007

Civil‐engineering construction works often have a significant impact on groundwater conditions. Such an impact can range from the derogation of water sources by dewatering works, to the creation of barriers and pathways for groundwater flow formed by foundations or ground‐improvement processes. In some cases, not all these impacts are identified early enough during the planning and design process.

This paper describes the full range of potential groundwater impacts which can result from construction activities. The effects are grouped into five rational categories as an aid to initial assessment. The need for accurate baseline groundwater environmental data is set out. and recommendations are made for the planning of monitoring programmes.
TREATMENT OF WASHWATER FROM SERVICE‐RESERVOIR CLEANING IN HONG KONG
Authors: Bradley R. M. , Watker‐Zeris A. , Ku C. C.
Published: July 2007

As a result of increasing control of environmental pollution in Hong Kong. the practice of discharging untreated service‐reservoir washwater to the nearest watercourse is no longer permitted. This paper describes the results of field tests on alternative methods of treating the effluents produced from cleaning fresh‐water and sea‐water service reservoirs in Hong Kong, including trials of alternative cleaning procedures using high‐pressure jetting which were designed to (a) upgrade the cleaning efficiency and (b) reduce the resulting pollution load. The results of effluent treatment, based on pilot‐plant trials incorporating various combinations of filtration and centrifugation, are presented. The option which was selected for full‐scale implementation, based on a mobile centrifugation and microfiltration unit, using a membrane developed in China specifically for the water industry, is described
A METHOD FOR INVESTIGATING THE POTENTIAL IMPACTS OF CLIMATE‐CHANGE SCENARIOS ON ANNUAL MINIMUM GROUNDWATER LEVELS
Authors: Bloomfield J. P. , Gaus I. , Wade S. D.
Published: July 2007

Previous approaches to assessing the impact of climate‐change scenarios on groundwater levels and groundwater droughts have focused on modelling specific recharge processes or phenomena. However, statistical methods, based on correlations between historic groundwater level and rainfall time‐series, provide an alternative and robust approach to predicting minimum groundwater levels and droughts. For the purposes of this study, groundwater droughts are defined in terms of the return period of a given groundwater level. A multiple linear regression model (regression of monthly rainfall totals for a given period against values of minimum annual groundwater levels for the same period), when used with synthetic rainfall data based on climate‐change scenarios, enables changes in future annual groundwater‐level minima to be modelled. The method is illustrated at three sites on the Chalk, Permo‐Triassic sandstone and Jurassic limestone aquifers.
ENVIRONMENTAL AND STRUCTURAL IMPLICATIONS FOR THE RE‐USE OF TYRES IN FLUVIAL AND MARINE‐CONSTRUCTION PROJECTS
Authors: Fenner R. A. , Clarke K.
Published: July 2007

There is increasing interest in reclaiming tyres for use in bank‐side and coastal‐protection structures. However, concern has been expressed about the potential for tyres to release pollutants into the environment and to retain their long‐term structural stability. This paper describes laboratory leaching tests for heavy metals from new used tyres and tyres which have been exposed to an aquatic environment for thirteen years. The results show that the limiting factor to their use could be cadmium release. Tests found evidence of the loss of ultraviolet screening agents such as carbon black, suggesting that chemical breakdown of the tyre through leaching of vulcanising chemicals is more significant in the physical breakdown of the tyre, than the reverse. Three case studies of tyre flood‐protection and river‐control structures are presented, which examine the ability of tyres to retain structural integrity over long periods. Based on this evidence, guidance on design principles is offered. It is concluded that tyres can be used sustainably in a river or coastal environment, subject to careful consideration of local site conditions.
A NEW CONCEPTUAL GROUNDWATER‐FLOW SYSTEM FOR THE CENTRAL SOUTH DOWNS AQUIFER
Authors: Robins N. S. , Dance L. T.
Published: July 2007

The central part of the South Downs Chalk aquifer is intensely used for public water supply. Although the aquifer has a long history of careful development and management, the outline conceptual groundwater‐flow vision has not been formally investigated for many years. A major programme of work has now been completed which (a) provides a new insight into the hydraulic workings of the aquifer, and (b) highlights a number of hitherto poorly understood concepts controlling groundwater movement in the Chalk. These include the key role of geological structure and the occurrence of hard bands and karst‐type groundwater flow as major controls over preferred flow‐paths. The new conceptualisation concludes that the main discharge area for the aquifer is laterally to the north‐south rivers and not directly southwards to the sea.
ECONOMIC DESIGN OF FLOOD‐ATTENUATION RESERVOIRS FOR URBAN AREAS EXPLOITING CATCHMENT HYDRODYNAMICS IN SOUTH‐WEST UK
Authors: Faulkner B. L.
Published: July 2007

Runoff from new development in urban areas tends to increase the downstream flood peak which has to be attenuated or accommodated in the river channel to avoid increases in flood risk. The built environment close to the river often makes river‐improvement works difficult, if not impossible. This paper introduces the concept of rising‐limb attenuation, to mitigate downstream flood risk — especially in urban areas. Relying on the implicit difference in runoff times of concentration between rural and urban areas, it is possible to design efficient, self‐regulating storage structures, to counteract increases in peak flow in the main urban watercourse, by attenuating the later contribution from less urbanised or rural tributaries. Because rising‐limb attenuation is partial and temporary, volumes of storage are much less than for conventional attenuation reservoirs, with consequent savings in land take and costs. Because the controlled flow is also less, the associated structure is also generally smaller and simpler. Implementations of this type of structure have been carried out in two locations in the UK, and the outline design of these structures is described by reference to a case study.
ANOMALOUS RESPONSE IN THE HALIFAX PROCESS
Authors: Dudley J. , Chambers B.
Published: July 2007

The Halifax process was first proposed as a means of minimising the bulking of activated sludge. In one system using this process, bulking continued to occur. An analysis of the process, using dynamic modelling tools, predicted that the process contains the potential for effluent quality to become worse as the hydraulic loading to the process is reduced — contrary to common experience with more conventional layouts.
USE OF UKCIP02 CLIMATE‐CHANGE SCENARIOS IN FLOOD AND COASTAL DEFENCE
Authors: Hawkes P. , Surendran S. , Richardson D.
Published: July 2007

Understanding the uncertainties and risks from climate change is necessary for managing and adapting to those risks. Climate‐change scenarios provide a starting point for assessing climate‐change vulnerability, impact and adaptation. In April 2002, the UK Climate Impacts Programme released new future climate scenarios and was based on modelling at the Hadley Centre, which included temperature, soil moisture, rainfall, runoff, sea‐level rise and wind speed. These data provide a consistent source of information for use in UK climate‐change impact studies.

This paper (a) summarises some of the results from this programme, (b) explores their implications, and (c) recommends how these results could be applied in UK flood and coastal defence. The opinions of about twenty selected individuals, who were involved in flood and coastal defence, were collated to assess current practice in the use of climate‐change information, requirements of climate‐change scenarios, and comparison of the content of UKCIP02 with those requirements.
DERIVING UNIT HYDROGRAPHS FOR SMALL CATCHMENTS
Authors: Gardner C. M. K. , Wilcock D. N.
Published: July 2007

An examination of 190 storm events in seventeen small Northern Ireland catchments, along lines developed by the UK Institute of Hydrology, shows that the time‐to‐peak of the instantaneous unit hydrograph can be estimated from catchment characteristics and from the time between the centroid of mass of a flood‐producing rainfall event and of the resulting peak flow, but that equations calibrated on British data overestimate the time‐to‐peak. This might be due to the distinctive hydrology of Northern Ireland.
CONSERVING WATER VOLES: BRITAIN'S FASTEST DECLINING MAMMAL
Authors: Strachan R.
Published: July 2007

In Britain, the water vole is a declining species because of habitat loss and land‐use change associated with the intensification of agriculture and urban encroachment. During recent years, this decline has accelerated due to predation by feral American Mink (escapees from fur farms) and population fragmentation. Legal protection and planning policy has allowed for conservation action to be incorporated into waterside developments. This paper examines the various options to maintain and enhance water‐vole populations through planning design, sensitive mitigation procedures and strategic habitat restoration.
KNOWLEDGE‐BASED SYSTEM ON WATER‐RESOURCE MANAGEMENT IN COASTAL WATERS
Authors: Chau K. W.
Published: July 2007

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 FORMATION OF A RIVER‐BASIN AUTHORITY THROUGH LOCAL PARTICIPATION: A CASE STUDY FROM THE SOUTHERN PHILIPPINES
Authors: Evans D.
Published: July 2007

Since Dublin hosted the International Conference on Water and the Environment in January 1992, the importance of (a) managing water resources at the most appropriate level, (b) the catchment, and (c) participation have been stated repeatedly at international forums. The developing principles in ‘integrated water‐resources management’have built upon these needs. Much effort and resources have been concentrated at the national and transboundary level; however, it is at the local level, in mainly financially resource‐starved countries, that such principles often need to be implemented.

This paper examines the progress in the formation of a river‐basin authority, through local initiation and consultation, and with limited resources within the Southern Philippines. It highlights the benefits of the process and the problems which were encountered, and draws together lessons that have a wider application than the case study itself.
EFFECT ON ESTUARINE FINE‐SEDIMENT TRANSPORT OF INTERMITTENT PUMP DISCHARGE AT PAGHAM HARBOUR, WEST SUSSEX
Authors: Mitchell S. B. , Burgess H. M.
Published: July 2007

Field investigations were undertaken to identify the mechanisms of fine‐sediment transport at a landward limit of Pagham Harbour. Which is a semi‐enclosed natural harbour in West Sussex, UK. Measurements of water level, velocity, salinity and turbidity were made during three tidal cycles between June and August 2002. Near‐bed measurements revealed that, for spring tides, the most significant transport occurs during the flood tide, with smaller turbidity peaks recorded at times of intermittent pumped discharges at low water. Vertical profiling revealed that the timing of these discharges acts as a control on the landward transport of fine sediment by increasing salinity stratification. The resulting graphs show that, while increased near‐bed velocity leads to increased turbidity and sediment transport, the degree of vertical salinity gradient is also linked with landward transport of fine sediment. These results help to explain the role of tides and fresh‐water flow in controlling the transport of fine sediment in natural harbours, emphasising the importance of taking stratification into account when using 2‐D depth‐averaged predictive numerical models.
WATER, LIFE AND CULTURE: THE WATER FRAMEWORK DIRECTIVE
Authors: Lewin K. , Burston P.
Published: July 2007

Although wetlands are referred to in the statement of purpose of the Water Framework Directive and in the objectives for groundwater status. there are few further references to Member States’obligations towards them in the body of the Directive or its annexes. This paper (a) describes wetlands and their functions, and argues that they play an essential role in aquatic systems, (b) explains the place of wetlands within the Directive, and (c) advocates approaches to implementation in the UK which will ensure maximum human and ecological benefit.
PYROLYSIS AND GASIFICATION OF SEWAGE SLUDGE IN A SPOUTED‐BED REACTOR
Authors: Paterson N. , Zhuo Y. , Reed G. P. , Dugwell D. R. , Kandiyoti R.
Published: July 2007

The use of sewage sludge as the fuel for fluidised‐bed gasifiers, which form part of combined heat and power systems, has been studied in an EU funded project. A laboratory‐scale spouted‐bed reactor was used to investigate the pyrolysis and gasification behaviour of a suite of sewage sludges in the temperature range 770–980°C and pressures between 0.2 and 0.4 MPa. High solids conversions were measured, on a dry ash‐free basis, which were consistent with the high volatile‐matter content of the sludge‐based fuels. It seems that most of the fuel was pyrolysed and converted to gas and condensable tars/oils. The proportion of hydrogen which was formed increased with the gasifier temperature and with the char bed height in the reactor, and this was consistent with an increase in the extent of cracking of the tars/oils. The nitrogen content of the sewage sludge was high, and this led to high ammonia concentrations in the fuel gas. Operating at the higher end of the temperature range tended to decrease the amount of ammonia in the fuel gas.
A RISK‐BASED CONSENTING TOOL FOR SETTING SUSTAINABLE DISCHARGE CONSENTS
Authors: Hankin B. G.
Published: July 2007

This paper describes the development of a guidance tool for assessing the ability of a receiving watercourse to assimilate pollution from point discharges. The ‘sustainable capacity tool’uses a framework that accounts for the ‘no‐deterioration’requirement of the Water Framework. Directive, in terms of the downgrading of a river‐stretch classification and the requirement to return all rivers to ‘good ecological status’. The second requirement results in a long‐term set of river‐quality targets or objectives, and it is generally assumed that ‘good’refers to ‘A2 quality in the Scottish Environmental Protection Agency classification system. The resulting sustainable capacity is defined as the risk‐based amount of capacity that could be allocated without causing a failure of the target class and which could also result in a negative capacity if the river stretch is currently failing the target class. This is plotted as a GIS layer and is intended to form an overview of water quality to help inform stakeholders who are participating in a water‐quality strategy for the next Scottish investment programme on Quality and Standards 3. The sustainable capacity tool could be used in conjunction with integrated catchment modelling for complete management of the Water Framework Directive river‐basin districts.
THE PERFORMANCE OF PILOT‐SCALE PRIMARY‐FACULTATIVE WASTE‐STABILISATION PONDS IN THE UK
Authors: Abis K. L. , Mara D. D.
Published: July 2007

Three pilot‐scale primary‐facultative waste stabilisation ponds were constructed at Esholt sewage‐treatment works, Bradford. Each pond received screened sewage at different BOD loading rates over a two‐year period. Concentrations of BOD, SS, amm. N and chlorophyll‐a were measured weekly in summer and bi‐weekly in winter, and sludge accumulation was measured after 3, 9, 15 and 20 months. BOD and SS removals were consistently high, although they were lower in summer than in winter due to high levels of algae. The removal of amm, N was generally much better in summer than in winter ‐ the removal mechanism being most likely related to algal activities. Sludge accumulation rates were very low.
PUBLIC PERCEPTION TOWARDS WATER RECYCLING IN CALIFORNIA
Authors: Bridgeman J.
Published: July 2007

This paper considers ways in which water undertakers in the USA have overcome problems associated with pre‐conceived negative opinions regarding water recycling. Three key recycling sites in California were identified, and a survey of the principal players and stakeholders was undertaken.

Research has indicated that outreach and educational programmes must be proactive in nature, focusing on the value of reclaimed water and emphasising the benefits to be gained from its use at an individual. community and environmental level. Recommendations are made regarding the format of public outreach programmes, stakeholder action plans and conclusions drawn regarding public opinion. Unless (and until) the concept is accepted by the general public, large‐scale water‐recycling projects, which ultimately include ingestion of the recycled product, are likely to fail.
ASSESSING AND MANAGING THE RISKS OF PATHOGEN TRANSFER FROM LIVESTOCK MANURES INTO THE FOOD CHAIN
Authors: Nicholson F. A. , Chambers B. J. , Moore A. , Nicholson R. J. , Hickman G.
Published: July 2007

A review was undertaken of (a) the levels and prevalence of Salmonella spp., Campylobacter spp., Listeria monocytogenes, Escherichia coli 0157. Cryptosporidium parvum and Giardia intestinalis in livestock manure, and (b) factors which affect their survival during storage and following land application. Pathogens are commonly present in livestock manures and can survive in soil for several months or years after spreading or excretion onto land. Temperature was identified as being the most important factor influencing pathogen survival, although pH, UV light and drying were also important. Various practical measures to minimise the risk of pathogen transfer into the food chain were identified, including treatment, extended storage and no/harvest periods following land spreading. Guidelines are being developed on managing farm manures to minimise the risks of microbiological contamination of ready‐to‐eat crops.
EARLY ARAB WATER TECHNOLOGY IN SOUTHERN SPAIN
Authors: Headworth H. G.
Published: July 2007

This paper describes many of the ways by which the Arabs in southern Spain, during their eight hundred years occupation. raised, stored and distributed water without pumps, reservoirs or pipelines. The technology which they used in their water mills was simple but ingenious and differed from that evolving in Britain at that time. Using contourhugging open channels, the Arabs transferred snowmelt from the sierra over long distances, to recharge the ground above the mountainside villages and sustain the spring flows to their fountains through the year.