bluuebunny/crossref_metadata_2025 huggingface dataset:
A Large‐Scale Grid‐Based Hydrological Model of the Severn and Thames Catchments
Authors: Jolley T. J. , Wheater H. S.
Published: July 2007

This paper addresses the issues of scale and appropriate model complexity for large‐scale hydrological models. A grid‐based hydrological model, which employs the UK Meteorological Office Rainfall and Evaporation Calculation System, is applied to the Severn and Thames catchments using a grid scale of 40 km, and is shown to reproduce the observed mean annual runoff over a 10‐year period to within 6% with no prior calibration. The variation in the model performance is strongly correlated with the linearity of the annual rainfall/runoff relationship and a climate index. At the monthly scale, runoff routing becomes significant, and the introduction of a two‐parameter routeing algorithm significantly improves the monthly runoff simulations giving efficiencies of 90% and 88% for the Severn and Thames respectively. The results provide guidance to climate modellers looking for efficient and robust land‐surface parameterizations, and indicate the potential application of such a modelling scheme to water resource managers.
Contamination of Chalk Groundwater by Chlorinated Solvents: A Case Study of Deep Penetration by Non‐Aqueous Phase Liquids
Authors: Lawrence A. R. , Stuart M. E. , Barker J. A. , Tester D. J.
Published: July 2007

The transport behaviour of chlorinated solvents, both in the aqueous phase and as a dense non‐aqueous phase liquid (DNAPL), in fissured microporous aquifers is reviewed. The presence of DNAPL in aquifers is especially serious as it is likely to be the main subsurface source of contamination and, given the slow rates of dissolution in groundwater, may persist for decades. However, the identification and quantification of DNAPLs in fractured aquifers present many practical problems and are often not achievable.

A case study of a Chalk site which had been contaminated by chlorinated solvents demonstrated that the use of a range of techniques, including depth profiling of solvent porewater concentrations in cored boreholes, can provide clear evidence for the presence of DNAPL at depth, although DNAPL was not itself observed. Theoretical considerations and field observations confirmed that DNAPL movement is via fractures rather than through the microporous matrix.
Institutional Development: What Are We Talking About?
Authors: Spencer A. L.
Published: July 2007

Nowadays it is almost the rule rather than the exception for overseas aid projects in the water and environmental sectors to include ‘institutional development’as a significant, if not the main, component. Yet institutional development is not a particularly well‐defined activity ‐ it being a combination of managerial, technical, organizational and behavioural techniques. Furthermore, the basic concepts in some of these fields are still in the evolutionary stages.

Starting from a definition of an institution and the purpose of an organization, a simple pragmatic approach to institutional development is described, based on many assignments undertaken in the field. The basis of the approach is a ‘3‐links’model which examines each of three components in turn, i.e. (a) relationships with the environment, (b) organizational issues, and (c) development of the individual. Finally, there are some comments on the criteria for a successful institutional development exercise.
Development of a Groundwater Resource Model for the Yorkshire Chalk
Authors: Salmon S. , Chadha D. , Smith D.
Published: July 2007

This paper (a) aims to demonstrate the basic principles of groundwater resource model development by means of an example, and (b) describes the development of the Yorkshire Chalk groundwater model (YORKMOD), undertaken on behalf of the National Rivers Authority † and Yorkshire Water Services. The model incorporates a permeability‐depth function to represent fissuring in the Chalk, and has been successfully calibrated against observed groundwater heads and springflows for the period 1975–1992 inclusive.
Environmental Effects of Hydro‐Electric Power Generation in Africa and the Potential for Artificial Floods
Authors: Acreman M. C.
Published: July 2007

Electricity is a fundamental requirement for economic growth, and hydro‐electric power is often thought to be environmentally benign. However, the construction and operation of many hydro‐power dams in Africa have had significant negative impacts on the environment and rural economies. Reduced downstream flooding has destroyed fisheries and starved the floodplain soils of moisture and nutrients. Often the worst‐affected areas have no electrification and therefore do not benefit from power generation. New dams which are planned in Kenya and Tanzania have been specifically designed to make flood releases. This will allow electricity to be generated whilst maintaining a dynamic flooding pattern for the short‐term economic importance of fisheries and agriculture and the longer‐term importance of soil fertility and biodiversity. Involvement of local community representatives in deciding when flood waters should be released on the Phongolo River in South Africa has resulted in substantial benefits to floodplain users.
From Manchester Docks to Salford Quays: Ten Years of Environmental Improvements in the Mersey Basin Campaign
Authors: Struthers W. A. K.
Published: July 2007

The decline of the former Manchester Docks and its resurgence as Salford Quays is described. The isolation of water within the Quays from the Manchester Ship Canal was a principal proposal of the development plan, and the water‐treatment system which was installed has been highly successful in creating a thriving aquatic ecosystem and enabling water‐based recreation activities to take place. Whilst the water quality within the Quays is excellent, outside in the Manchester Ship Canal it remains grossly polluted. Under the auspices of the Mersey Basin campaign, the various partners are involved in a major project to clean up the canal. The Lowry Centre, a Millennium Fund bid, is giving an added impetus to this work. The conclusions identify the involvement of the local council as being critical to the success of the project, and that a respect for quality has been essential, as has a long‐term commitment to an overall vision.
Assessment of the Fate of Selected Adsorptive Pesticides at ADAS Rosemaund
Authors: Turnbull A. B. , Harrison R. M. , Williams R. J. , Matthiessen P. , Brooke D. N. , Sheahan D. A. , Mills M.
Published: July 2007

Data are presented on four pesticides applied to agricultural land at the Agricultural Development Advisory Service, Rosemaund, in the west of England. The farm covers a well‐defined and isolated water basin of cracking heavy clay loam soils drained by a single stream. Levels of the relatively particle‐bound pesticides trifluralin, deltamethrin, chlorpyrifos and fenpropimorph were measured in drainage water and field soils following application. Observed concentrations in water were generally below 1 μg/l with occasional peak levels exceeding 10 μg/l during storm rainfall events. Unexpectedly high peak levels of deltamethrin of around 2 μg/l highlighted significant bypass flow mechanisms from the surface soils during the autumn. Additional bioassay experiments showed that levels of chlorpyrifos, lethal to Gammarus pulex, reached the stream during spring 1993. The Rosemaund farm has been the site of a continuing investigation into the movement of agricultural pesticides to surface waters since 1987, and this report represents the final work conducted in the autumn of 1992 and spring 1993.
Applications of Anaerobic Digestion for the Treatment of Industrial Wastewaters in Europe
Authors: Wheatley A. D. , Fisher M. B. , Grobicki A. M. W.
Published: July 2007

For many decades, anaerobic digestion has been the most important technique of sewage sludge treatment at larger sewage‐treatment works. Also, the low running costs of the process make it attractive for the treatment of strong industrial effluents. This paper reviews these advantages and discusses some disadvantages of the anaerobic treatment of industrial effluent. Operating and cost data are presented from Europe and from a detailed UK case study which supports the conclusion that anaerobic treatment will be the most cost‐effective method of treatment of strong industrial effluents such as those from food and paper processing.
Risk Assessment for a Proposed Groundwater Abstraction Scheme in Strathmore, North‐East Scotland: a Modelling Approach
Authors: Chen M. , Soulsby C.
Published: July 2007

The Lower Old Red Sandstones in northern Strathmore have favourable hydrogeological conditions for ground‐water development. A scheme was proposed to abstract water in the north Esk catchment in order to augment water supplies to local villages, and a production borehole was drilled into the Edzell Sandstones to give a design yield of 2420 m3/d. However, this scheme has been abandoned because of concern that the abstraction would significantly reduce the flow in a nearby stream which is an important salmonid fishery.

This study demonstrates the potential value of using a stream‐aquifer numerical model in an environmental risk assessment for the proposed scheme.
The Design of Conventional and Siphonic Roof‐Drainage Systems
Authors: May R. W. P.
Published: July 2007

The hydraulic principles governing the performance of conventional and siphonic roof‐drainage systems are described and compared. The flow rate in a conventional system is determined by the depth of water in the gutter or on the roof. Siphonic systems are able to achieve higher flow rates because they make full use of the head available between the roof and the discharge point at ground level.

Some special operating characteristics of siphonic systems are described and recommendations are made on the factors that should be considered in their design.
Desalination: the State of the Art
Authors: Wade N. , Callister K.
Published: July 2007

Desalination technology is applied in many areas of the world to provide fresh water from brackish or seawater sources. The paper reviews the technology which is available and discusses both distillation and membrane processes. Indications of capital and operating costs are provided.
The Influence of Sampling Frequency on Streamflow Chemical Loads
Authors: Roberts G.
Published: July 2007

In this paper, monthly loads in the streamflows from a number of UK catchments were calculated using all available chemical data and two degraded data sets comprising one value per month, thus simulating the ‘harmonized monitoring scheme’of the Environment Agency †. These degraded data sets represent the lowest and highest concentrations of the various chemical determinands. Two‐load calculation algorithms were used; one employing continuous‐flow records plus instantaneous values, and the other employing instantaneous values only. The results of these algorithms were compared for each determinand ‐ in terms of absolute values and the range of values possible using the degraded monthly sampling intervals.
Accounting for Polycyclic Aromatic Hydrocarbons in Public Water Supplies
Authors: Lindley E.
Published: July 2007

Asset management plans were prepared in 1989 and 1994 by water companies in England and Wales for submission to the Office of Water Services. These plans constituted the financial programming required by water companies to meet specified standards of service, particularly with respect to water quality. Detailed studies have previously established that problems associated with iron from unlined ferrous mains, particularly in soft water areas, is often the main cost ‘driver’for water distribution investment. However, many of the so‐called unlined iron mains were treated with a coal‐tar pitch lining for corrosion protection before installation, and residues of this painted lining can give rise to unsatisfactory levels of polycyclic aromatic hydrocarbons in drinking water.

The paper describes how desk‐study research, followed by the development and application of a modified ‘focused downstream series sampling’water‐quality modelling technique allowed polycyclic aromatic hydrocarbons to be accounted for in two water company asset management plan submissions. The paper also raises a number of fundamental implications with respect to the occurrence of these carcinogenic compounds in drinking water.
Orthophosphate Concentrations in the River Thames
Authors: Kinniburgh J. H. , Tinsley M. R. , Bennett J.
Published: July 2007

Observed concentrations of orthophosphate in the River Thames, from its source to its tidal limit, exceed 0.1 mg P/1 for most of its length; reasons for annual and seasonal variations are explained. By using data routinely collected by the Environment Agency throughout the Thames catchment, the orthophosphate load in the river, derived from agricultural sources and sewage‐treatment works, is estimated.

A water quality model, TOMCAT, has been adapted to simulate observed data and used to estimate river concentrations if orthophosphate loads from sewage‐treatment works are reduced.
Estimating Small Area Demand for Water: A New Methodology
Authors: Clarke G. P. , Kashti A. , McDonald A. , Williamson P.
Published: July 2007

The estimation of water demand is fundamental to effective water resource management. Water supply is measured at district level but true demand is not, and therefore studies of water‐pricing relations are limited and mass‐balance based assessment of leakage, illegal use, meter inaccuracies etc., are compromised. This paper describes the value and limitations of existing geodemographic methods, and an alternative technique widely used in other fields, microsimulation, is proposed. It is shown that geographic stability in demand relations is not found in all consumer commodities and cannot be assumed for water. Sampled data for Leeds, West Yorkshire, are used to construct a microsimulation model, and the results of that model are applied to the city of Leeds at ward level. Applicability is also demonstrated at enumeration district level.
Effective Passive Treatment of Aluminium‐Rich, Acidic Colliery Spoil Drainage using a Compost Wetland at Quaking Houses, County Durham
Authors: Younger P. L. , Curtis T. P. , Jarvis A. , Pennell R.
Published: July 2007

Passive treatment of net‐acidic minewaters using compost wetlands was pioneered in the USA but, so far, has had limited application in Europe. At Quaking Houses (County Durham), strongly acidic ferruginous and aluminium‐rich waters discharging from the spoil heap of the abandoned Morrison Busty colliery have been obliterating aquatic life in the Stanley Burn for almost a decade. A concerted investigation involving the National Rivers Authority, the local community and a nearby University, has established the origins of the polluting discharge and assessed its impact on the receiving water. An evaluation was carried out on the possible treatment methods for the discharge, drawing upon the literature and supported by laboratory microcosm tests. A compost wetland was the favoured option, and a pilot facility was constructed with the assistance of the local community.

Plans for full‐scale treatment are now well advanced, with long‐term maintenance being undertaken by local volunteers at minimal cost.
Side‐Stream Treatment of Raw‐Sludge Liquors using Activated Sludge: Pilot Investigations and Full‐Scale Design Rationale
Authors: Fawcett N. S. J. , Siddall R. A. , Wheak G.
Published: July 2007

The end of sludge disposal at sea in 1998 will lead to increased volumes of sludge requiring treatment and disposal. Accordingly, there will be further quantities of high‐strength liquors arising from sludge thickening and dewatering processes, and additional treatment capacity will therefore be required at treatment works.

This paper describes a three‐year project to develop a dedicated side‐stream treatment process for the treatment of raw‐sludge liquors at Knostrop sewage‐treatment works (Leeds) based on the activated‐sludge process. Large pilot‐scale trials are described which assisted in the construction of simple process design models for full‐scale design. Together with additional pilot‐scale aeration testing and modelling, a cost model for a full‐scale plant was developed, allowing the lowest whole‐life cost plant, based on ‘net present cost’analysis, to be specified.
Hydraulic Performance of Completely Mixed Tanks in Series under Unsteady Flow
Authors: Peng J.
Published: July 2007

Completely mixed tanks in series are often used in water and wastewater treatment processes and surface‐water quality modelling. Hydraulic retention time, which describes the overall hydraulic performance of the tanks, is one of the main parameters in the design and operation of treatment processes and modelling of the surface‐water quality. Differential equations to calculate the hydraulic retention time of completely mixed tanks in series under unsteady flow were derived in this study, and the equations were subsequently used to evaluate the hydraulic performance of tanks under a step change inflow rate and a cyclical flow rate, respectively. For a step change in flow rate, the differential equations were solved analytically using a recursive method. For a cyclical hydraulic loading, computer simulation was carried out using the Runge‐Kutta method with adaptive stepsize control.
The Role of Geomorphology in Monitoring and Managing River Sediment Systems
Authors: Newson M. D. , Sear D.
Published: July 2007

This paper reviews the contribution that can be made to land‐drainage and flood‐defence practice by consideration of the sediment transport system of river catchments. It also outlines the problems posed by not monitoring sediment transport over wider and longer time and space scales than are conventionally adopted. The contribution made by geomorphology to this aspect of river management is identified, and examples of its application to flood‐defence problems are given.
Fast‐Track Provision of St. Aidans Reverse‐Osmosis Water‐Treatment Plant
Authors: Wilson D. , Brown D.
Published: July 2007

As a response to the drought of 1995–96, Yorkshire Water constructed an emergency water‐treatment plant to treat water from a flooded opencast site at St. Aidans near Leeds. The main process was low‐pressure reverse osmosis to remove ammonia and trace organic micro‐pollutants to produce the required water quality at all times. This paper describes the plant which was designed and constructed in thirteen weeks ‐ a fast‐track project which was made possible by the close cooperation between the client, the consultant, and the contractor.
Hazards of Industrial Anaerobic Digester Effluent Discharges to Sewer
Authors: House S. J. , Evison L. M.
Published: July 2007

With the increase in use of anaerobic digesters in industry, there is concern that the direct discharge of effluents (from such plants) to sewer could cause explosive conditions because of increased methane production. The study explored this issue by undertaking laboratory analyses of methane‐production rates of sewage and anaerobic digester effluents. A particular sewer was studied and basic calculations were undertaken to try and establish the risk of methane build‐up to dangerous levels.
Assessing the Reliable Outputs of Groundwater Sources
Authors: Beeson S. , Misstear B. D. , Van Wonderen J. J.
Published: July 2007

The described methodology for the assessment of the reliable outputs of groundwater sources was developed during a recent contract for UK Water Industry Research. It is relatively simple and flexible so that it can be applied to the wide range of groundwater source types and aquifers encountered in the UK. It can be used for all water level conditions, including that of drought, and for various demand conditions. There are two approaches, one based upon operational data and the second upon the analysis and extrapolation of pumping test data. The operational approach has several options of increasing refinement – the choice of option depending on data availability and user requirements. The application of the methodology to real groundwater sources is described using three examples.
The Use of Different Conveyance Calculations for Modelling Flows in a Compact Compound Channel
Authors: Lyness J.F. , Myers W. R. C. , Wark J. B.
Published: July 2007

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.
Flow Estimation from Flap‐Gate Monitoring
Authors: Burrows R. , Ockleston G. A. , Ali K. H. M.
Published: July 2007

The measurement of flows and recording of storm events at combined sewer overflows are a key requirement in effective urban pollution management. Staff of Thames Water Utilities have developed a low‐cost system based on monitoring the behaviour of flap valves on numerous major river outfalls. The paper presents the development of a modelling approach based on the principle of conservation of angular momentum and its application to experimental data for circular gates. Flow‐prediction accuracies, based on the measurement of gate inclination and water depths, in the range ± 20–30%, are found to be achievable for wider gate openings (<20°) – the recommended calibration offering conservative flow predictions at lower angles.
A Simple Method for Estimating Mean Annual Groundwater Recharge for Drift‐Free Areas of the Chalk and Permo‐Triassic Sandstone Aquifers in the UK
Authors: Finch J. W. , Geol C. , Ragab R. , Harding R. J.
Published: July 2007

At present, several methods for estimating groundwater recharge are in use in the UK, resulting in a range of estimates of groundwater recharge in any one area. However, there is a need for a robust national methodology with a firm scientific basis. As a first stage, a simple method has been developed to allow the rapid estimation of the mean annual groundwater recharge on drift‐free areas of the major aquifers of England and Wales.

A simple soil‐moisture model, with inputs of daily rainfall and potential evaporation, has been used to produce a series of nomographs. These can be used to estimate (a) mean annual groundwater recharge from data which are readily available, (b) annual values of rainfall, and (c) MORECS potential evaporation for grass. These estimates are aggregated to give the total for the area by including information on the land cover.
The Use of Water for Agricultural Irrigation
Authors: Stansfield C. B.
Published: July 2007

This paper summarizes the present position of agricultural spray irrigation in England and Wales, providing (a) national statistics and regional information, (b) the reasons why farmers irrigate, (c) the place of agriculture in the economy, and (d) the value of irrigation. A review of the Ministry of Agriculture, Fisheries and Food irrigation surveys highlights the important crops in terms of area and volume of water used, sources of water and storage, and application methods. The predictions for the future, including the effects of climate change are reviewed with examples of how farmers, the EA, and the agricultural industry, are helping to overcome problems.
Uncertainty in the Engineering of Wildlife Habitats
Authors: Brookes A. , Downs P. , Skinner K.
Published: July 2007

Environmental systems are inherently unstable over time‐scales appropriate to planning and management. As knowledge relating to rivers and their floodplains increases, uncertainty is increased rather than decreased. As the limits of what is known become defined, a better appreciation of what is not known is gained.

The creation of wildlife habitats in rivers and on floodplains has been referred to as an art rather than a science. This paper highlights some of the many questions which remain unanswered as environmental managers strive for more sustainable and cost‐effective projects.
The Development and Application of Phosphorus Removal from Wastewater using Biological and Metal Precipitation Techniques
Authors: Strickland J.
Published: July 2007

The paper describes a programme of technology development in phosphate removal which was carried out by Anglian Water in response to the requirements of the urban waste water treatment Directive Trials covered pilot and large‐scale biological nutrient‐removal plants, and iron‐salt dosing to activated‐sludge plants and biological filters. The fundamentals of the processes are discussed and results are presented.
Main Drainage Design for the New Kuala Lumpur International Airport
Authors: Mosquera S. T. , Drake J. M.
Published: July 2007

The new Kuala Lumpur International Airport in Malaysia requires substantial works for the management and attenuation of surface‐water runoff from a large platform constructed on both high ground and low‐lying swamp. This paper describes the key features of the main drainage system and reviews (a) the hydrological context of the scheme, (b) the design principles, and (c) the methodologies which were adopted. The platform drainage works comprise concrete‐lined open channels discharging through large balancing ponds into the local rivers. Other components of the scheme include numerous culverts, a river diversion, and an interim system to drain the earthworks’platform prior to completion of the permanent airport drainage. Measures to mitigate the impact of the development, and the application of hydrodynamic modelling in optimizing the system design, are discussed.
The Microbiological Quality of Private Water Supplies
Authors: Fewtrell L. , Kay D. , Godfree A.
Published: July 2007

This paper provides a detailed assessment of the microbiological quality of a selection of private water supplies. Samples were taken from 91 supplies and analyzed for total coliforms, faecal coliforms and faecal streptococci. The microbiological quality of the samples was generally poor, with almost 50% of the supplies failing to meet the required standards on at least one occasion. Given the high level of sanitary microbiological failures, there is the possibility that harmful microorganisms could be present and a significant risk to health cannot be discounted.
The Stability of the Oxford Clay as a Mineral Liner for Landfill
Authors: Batchelder M. , Mather J. D. , Joseph J. B.
Published: July 2007

The paper discusses the mineralogical and chemical stability of the Oxford Clay as a landfill liner for the containment of domestic waste. The results from a series of batch equilibrium experiments with the mudrock and a synthetic leachate are compared with samples of a liner cored from a 15‐year‐old site in the Formation. The effects of leachate on the Clay include mineral dissolution, exchange of cations, particle‐size reduction and collapse of illite‐smectite. In situ mixed‐assemblage mineral liners, such as the Oxford Clay, are capable of attenuating leachate components and buffering acid leachates whilst the predominant clay minerals, i.e. illite and kaolinite, remain stable. Alterations to the mineralogy and chemistry of the samples resulting from both short‐term and long‐term exposure to leachate are discussed with reference to the implications to landfill practice.
Factors Governing Macrophyte Status in Hampshire Chalk Streams: Implications for Catchment Management
Authors: Wilby R. L. , Cranston L. E. , Darby E. J.
Published: July 2007

Severe droughts in the late 1980s and 1990s have highlighted the fragility of many aquatic environments in southern England; in particular, declining river flows may be having an adverse affect on macrophytes in the chalk‐fed streams of the Rivers Test and Itchen. Detailed macrophyte survey data which were collected from representative sites in both rivers during 1991–1995 are interpreted in the context of changing hydroclimatic, water quality and in‐stream channel conditions. Multivariate statistical analyses support the assertion that river flow is the most significant parameter governing observed changes in macrophyte cover. During low flow years, filamentous algae have increased at most sites to the detriment of Ranunculus spp. These findings have catchment‐management implications which should be addressed if the long‐term integrity of such aquatic ecosystems is to be safeguarded.
The Use of the Water Velvet Azolla Filiculoides in Wastewater Treatment
Authors: Ghobrial M. G. , Siam E. E.
Published: July 2007

Azolla filiculoides is a free‐floating water fern which fixes atmospheric nitrogen in association with the nitrogen‐fixing blue‐green alga Anabaena azollae. It is used for nutrient‐removal purposes because it can grow under a wide range of environmental conditions.

This paper describes a series of experiments which was carried out in Alexandria, Egypt, to elucidate the performance of Azolla for the treatment of sewage and nutrient removal.
The Use of Economic Instruments for Water Management in Selected EU Member Countries
Authors: Zabel T. F. , Andrews K. , Rees Y.
Published: July 2007

The use of economic instruments for environmental management is being encouraged by the European Commission for the management of water abstractions and effluent discharges. Economic instruments are being applied increasingly by EU Member States to complement the traditional ‘command and control’approach, based on the licensing system. However, the design and the purpose of the charging schemes, and the levels of charges raised in the different EU Member States, vary widely.

This paper (a) discusses the use of abstraction and effluent charges applied in France, Germany, The Netherlands, and England & Wales, (b) assesses the impact of the schemes on water abstractions and effluent discharges, and (c) evaluates the feasibility of the application of incentive charging schemes.
The Recreational Value of Cley Marshes Nature Reserve: An Argument Against Managed Retreat?
Authors: Klein R. J. T. , Bateman I. J.
Published: July 2007

In the shoreline management plan for the coast of North Norfolk (England), managed retreat has been identified as the most preferable option for the Cley Marshes nature reserve. In general, arguments in favour of managed retreat are (i) opportunities for nature restoration and development, (ii) economic efficiency, and (iii) enhanced resilience to environmental stress and shock. However, with respect to the Cley reserve, recent floods have shown that increased salinity is likely to decrease its natural value, while this study shows that the economic‐efficiency criterion is not valid either.

This paper discusses the application of contingent valuation and travel‐cost methods on data collected by interviews of 160 visitors to the reserve, which has provided estimates of the annual recreational value of the site.
Hydraulic Performance of Environmental Features in Rivers
Authors: Ferguson R. M. , Lyness J. F. , Myers W. R. C. , O'Sullivan J. J.
Published: July 2007

From 1986 to 1992 a drainage improvement scheme was undertaken on the River Blackwater, Northern Ireland, following which the Department of Agriculture (for Northern Ireland) carried out a programme of fishhabitat reconstruction in an attempt to restore the river's depleted stock. Over three hundred sites were refurbished by introducing pools, spawning and nursery areas.

This paper investigates the hydraulic performance of the refurbished habitats, with particular interest in the roughtness characteristics of the incorporated features.
Dynamic Process Modelling of Activated‐Sludge Plants
Authors: Smith M. , Dudley J.
Published: July 2007

This paper reviews the developments in process modelling, and outlines the benefits of dynamic modelling compared to steady‐state modelling. The alternative uses of modelling, for design, operation and training, are included. The models covered are the COD‐based models from the IAWQ models #1 and #2 and WRc's BOD‐based model. The relevance of BOD modelling for practitioners, rather than academics, is discussed, and likely routes for the future development are presented.

The authors’practical experience using these models, principally under WRc's STOAT software, is also presented in the form of case studies ‐ highlighting the experience of sampling programmes, calibration, validation and the continuing importance of the engineer's role.
Faecal‐Indicator Budgets for Recreational Coastal Waters: A Catchment Approach
Authors: Wyer M. D. , Kay D. , Crowther J. , Whittle J. , Spence A. , Huen V. , Wilson C. , Carbo P. , Newsome J.
Published: July 2007

This paper explores the application of a catchment faecal‐indicator budget approach to the examination of faecal‐indicator sources impacting on coastal recreational water quality. This involves (i) the characterization of water quality in sewage effluent and riverine inputs, and (ii) measurement and estimation of input flows; the product of these components yields the input flux of indicator organisms from each source. The impact of sewage‐treatment scenarios on budgets is also investigated.
An Integrated Approach to Flood Forecasting and Warning in England and Wales
Authors: Haggett C.
Published: July 2007

Flood‐warning systems have been researched and discussed for several decades, and there is a large degree of consensus among researchers that an integrated approach to such systems is the most effective. There is evidence to show that flood‐warning systems are rarely operated in an integrated way and, as a consequence, tend to function sub‐optimally. The new powers vested in the Environment Agency in 1996, to oversee the total warning process in England and Wales, provide a unique opportunity to develop an integrated approach to flood detection, forecasting, warning dissemination and response, and therefore an improved service to other agencies and communities at risk from flooding.
Groundwater Exploitation and Development: Some Current Issues in Scotland
Authors: Robins N. S. , Ball D. F.
Published: July 2007

The increasing cost of water in public supply is providing renewed interest in groundwater from industry and other intensive water‐users. At present, groundwater in Scotland enjoys considerable advantages: over surface water. However, there are also disadvantages: in some areas groundwater quality is poor due either to anthropogenic activity or the natural occurrence of acidic groundwaters. The future groundwater development and management policy for Scotland is being formed around the Water Resources Framework Directive and the Groundwater Action Programme. However, there are several policy constraints which urgently need to be addressed; these include (a) the role of the Water Order and (b) the need for a licensing system to control abstraction from selected aquifer units.
An Assessment of Groundwater Recharge on the Channel Island of Jersey
Authors: McCartney M. P. , Houghton‐Carr H. A.
Published: July 2007

On the Channel Island of Jersey, a third of the total water requirements are obtained from groundwater sources. A reliable estimate of recharge is necessary for sustainable groundwater management. Past resource management has been limited, partly because the rate of recharge is uncertain.

This paper describes the application of three independent methods of estimating recharge: (a) chloride balance, (b) stream baseflow analysis, and (c) rainfall‐recharge‐runoff simulation. All three methods produce reasonably consistent results, indicating that long‐term recharge is 16–19% of average annual rainfall, and results of modelling indicate that groundwater abstraction may have exceeded recharge in 5 out of 28 years. These findings have important implications for the management of the island's water resources.
Validation of the Sewage‐Treatment Odour‐Prevention (STOP) Model
Authors: Yang G. , Hobson J.
Published: July 2007

A sewage‐treatment odour‐prevention model has been developed as a result of investigations using an environmental wind tunnel. The model was validated at a full‐scale sewage‐treatment works and realistic estimates of odour‐emission rates from a variety of sewage‐treatment processes were obtained. The model can be used to predict odour and hydrogen sulphide gas‐emission rates from many types of sewage‐treatment processes, offering (a) improved reliability in odour‐emission rate quantification, (b) reduced monitoring costs, and (c) an improved insight into the causes of odour problems.
A Mental Model's Approach to Customer Perception of Drinking‐Water Supply and Quality
Authors: Owen A. J. , Colbourne J. S. , Clayton C. R. I. , Fife‐Schaw C.
Published: July 2007

This study uses the psychological framework of ‘mental modelling’ to compare what experts and laypeople think about the hardness of drinking water. A drinking‐water quality mental model was developed using influence‐directed network procedures. This was evaluated in qualitative studies in Oxfordshire and the findings revealed gaps in laypeople's knowledge about the water‐supply process.
Disinfection With Peracetic Acid for Domestic Sewage Re‐Use in Agriculture
Authors: Liberti L. , Lopez A. , Notarnicola M.
Published: July 2007

This paper describes a four‐month pilot study on peracetic acid disinfection of unchlorinated tertiary effluent for unrestricted re‐use in agriculture carried out at West Bari (Italy) sewage‐treatment works. Dosages and contact times ranging from 1 to 500 mg/1 and 5 to 60 mins, respectively, indicated that 10 mg/1 of peracetic acid, with a 30‐min contact time, achieved the WHO faecal coliform guideline (1000 CFU/100ml). Much higher doses (£400 mg/l and 30 mins) were required to meet the corresponding Californian limit of two colony‐forming units/100 ml, which has also been adopted in Italy. Efficient mixing of the disinfectant (in one shot addition) was mandatory ‐ particularly at lower dosages (1–10 mg/l) where there was a higher concentration of suspended solids (>5 mg/l).
The Impact and Sustainability of Community Water Supply and Sanitation Programmes in Developing Countries
Authors: Carter R. C. , Tyrrel S. F. , Howsam P.
Published: July 2007

Sound strategies for community water supply and sanitation programmes in developing countries should be based on (i) a clear understanding of the existing problems, (ii) the beneficial impacts achievable, and (iii) the factors which determine sustainability. The impacts of many water and sanitation programmes are limited, and many systems break down and are abandoned prematurely; only limited impacts are achievable in the short term without greatly increased investment. Sustainability, in the sense of continued delivery and uptake of services, is threatened by numerous attitudinal, institutional and economic factors, and community participation approaches alone are no guarantee of success. The key to sustainability is that all stakeholders involved in consumption/use, maintenance, cost recovery, and continuing support, perceive it in their best interests to deliver high‐quality services.

This paper, based upon the authors' experiences in Africa and Asia, proposes new sets of programme aims and objectives in relation to impact and sustainability, which can be used in programme design, monitoring and evaluation. It also makes longer‐term recommendations to external support agencies.
The Application of Geomorphology to the Management of River‐Bank Erosion
Authors: Walker J.
Published: July 2007

This paper briefly reviews the evolution of river‐bank erosion management and the developing role of geomorphology in this field. The location and design of a traditional solution to erosion on the River Brock, Forest of Bowland is considered, and its failure under moderate flood conditions is analysed. The geomorphological processes at work at the site are identified and assessed, and conclusions for the ongoing management of the site are presented. The future role of geomorphology in river managment is also considered.
Guidelines for Greywater Re‐Use: Health Issues
Authors: Dixon A. M. , Butler D. , Fewkes A.
Published: July 2007

This paper discusses the potential threat to health associated with the microbial contamination of grey‐water. Although it has been shown that greywater may contain large numbers of potentially pathogenic microorganisms, the incidence of disease is dependent upon more than just the concentration of organisms. Other factors include the degree of exposure and the health and age of affected individuals. Proposed guidelines for the re‐use of greywater focus upon faecal coliform contamination and suggest limits based upon the end use of recycled water.

The paper (a) proposes modifications to the guidelines to better represent the delicate balance between protection of public health and the levels of risk posed by greywater re‐use within the context of everyday human activity, and (b) attempts to identify areas where there is either an expectation for responsibility or a personal acceptance of responsibility with regard to public or personal health.
Dissolved‐Oxygen/Suspended‐Solids Concentration Relationships in the Upper Humber Estuary
Authors: Mitchell S. B. , West J. R. , Guymer I.
Published: July 2007

Results of dissolved‐oxygen concentration from continuous monitors at one location on the (Yorkshire) tidal Ouse and two locations on the tidal Trent have revealed a strong dependence upon the concentration of suspended sediment. High concentrations of sediment lead to a lowering in dissolved‐oxygen levels. A comparison of this effect between the two rivers reveals lower dissolved‐oxygen concentrations in the River Ouse than in the River Trent for a given concentration of suspended sediment, which is partly due to a difference in the quality and quantity of pollutant discharges into the Ouse compared with the Trent. Because the concentration of suspended solids at a given location is known to be dependent upon the fresh‐water flow and the tidal range, it is concluded that the dissolved‐oxygen concentration is also strongly dependent upon conditions of fresh‐water flow and tidal range for these two tidal rivers.
Groundwater Occurrence in the Lower Palaeozoic and Precambrian Rocks of the UK: Implications for Source Protection
Authors: Robins N. S.
Published: July 2007

Lower Palaeozoic and Precambrian rocks are distributed in Scotland, Northern Ireland, Cumbria, Wales and the Channel Islands, and coincide largely with upland areas. Groundwater flow and storage is mostly shallow and flow paths are short, although there is some limited deeper groundwater circulation. Groundwater quality is variable but often weakly mineralized, reflecting incomplete water‐rock reaction. There are many small groundwater sources used for private supply and a number also for public supply; these offer an important social and economic asset to isolated rural and island communities. Groundwater occurs in four rock types: fractured rock, fractured rock with regolith, massive rock and karstic limestone. Identification of specific groundwater settings within these rock types provides an insight into the prevailing groundwater flow paths. This enables source protection zones to be prescribed according to the hydrogeological setting rather than by detailed data collection and modelling. This method of prescription is applicable universally to basement aquifers and is not limited to those in the UK.
An Assessment of the Suitability of the Environment Agency's Water‐Quality Classification System for Use in Urban Catchments
Authors: Green A. , Faulkner H.
Published: July 2007

Despite the increasing range of water‐quality indicators, the classification and target‐setting strategy which has been adopted by the Environment Agency for England and Wales is dominated by the assessment of water chemistry at low flow. Using the example of Pymme's Brook in north London, this paper examines the suitability of such data for classifying the quality of urban watercourses and its ability to reveal quality changes. The data expose a weakness in the Environment Agency's methodology, because they suggest that, when used alone, chemical monitoring leads to water quality being greatly over‐estimated and inappropriate targets being set. It is therefore recommended that other quality indicators should be fully integrated into the assessment system in order to overcome these problems.
Laboratory‐Scale Investigations of Algal Toxin Removal by Water Treatment
Authors: Hall T. , Hart J. , Croll B. , Gregory R.
Published: July 2007

The paper describes some water‐treatment processes which have been investigated on a laboratory and pilot‐plant scale for their effectiveness in removing toxic algal cells and the dissolved toxins microcystin‐LR and anatoxin‐a. Oxidation with ozone or potassium permanganate, or treatment by biological activated carbon, were found to be the most effective processes for removal of the dissolved toxins. Chlorination was effective only for the removal of microcystin‐LR. Toxins, contained within algal cells, could be removed effectively by coagulation, clarification and filtration under suitable conditions. Consideration of the structure and properties of micro‐cystin variants suggests that treatments which are suitable for removal of microcystin‐LR and anatoxin‐a should be suitable for removal of other microcystins.
An Assessment of Water Demand Management Options from a Systems Approach
Authors: Foxon T. J. , Butler D. , Dawes J. K. , Hutchinson D. , Leach M. A. , Pearson P. J. G. , Rose D.
Published: July 2007

A systems approach is used to model the urban water and wastewater system. Scenarios are developed for the implementation of a range of water demand management measures, including (a) leakage reduction, (b) the increasing use of water metering, (c) the replacement of standard WCs by low‐flow WCs, and (d) the introduction of greywater recycling systems. These measures are assessed according to the water saving, cost per unit of water saved, and other indicators of the relative contribution to the sustainability of the system. Preliminary assessments of selected environmental costs and benefits are also included.
Modelling the Potential Effects of Climate Change on the Grande Dixence Hydro‐Electricity Scheme, Switzerland
Authors: Westaway R.
Published: July 2007

For mountain communities which depend upon glacierfed hydro‐electric power schemes as an important source of energy, climate change poses a considerable threat. However, relatively few studies have examined this threat by investigating the joint impacts on meltwater production and energy use. In this paper, a simple water‐balance model is used to combine the results of ice‐melt and energy‐demand models to estimate the water level for the Grande Dixence reservoir, Switzerland. The potential impact of climate change on the scheme is also assessed using a regional climate‐change scenario.
The Mersey Valley Sludge Story: From Sea to Shell Green
Authors: Belshaw C.
Published: July 2007

The sludge from sewage‐treatment plants in the Mersey Valley has been disposed of at sea for over a hundred years. From 1897 until 1986, inland towns took advantage of the Manchester Ship Canal to provide the route to the sea. However, a decline in canal traffic in the 1960s and 1970s resulted in increased costs, and North West Water investigated cheaper alternatives. In 1981, an ambitious and radical new project commenced, i.e. the construction of an 86 km long, high‐pressure sludge pipeline, connecting Oldham with Liverpool.

Sea disposal ceased in December 1998 and North West Water has constructed a new sludge processing centre at Shell Green, Widnes, to replace the shipping operation. This paper describes the history of the shipping operation and the Mersey Valley sludge pipeline, together with operating experiences, leading to the construction of the new processing centre.