The National Rivers Authority's Need for Models

The Water Resources Act 1991 requires the National Rivers Authority to exercise a general supervision over all matters relating to flood defence. There is need for information in order to manage flood defence – not only as part of the overall management of the catchment but, at a more detailed level, to plan and monitor capital and maintenance programmes.
The information requirements of the National Rivers Authority can be satisfied either by witnessing historic flood events, an approach disadvantaged by the infrequency of flood events, or by modelling the system, i.e. the rivers, coasts and flood plain. Once models are calibrated by specific flood events they can be used to predict the outcome of other events and to assess the response required to alleviate potential flooding. The different needs of the Authority can be satisfied by different modelling techniques using different levels of accuracy. Models can be used to analyse river and coastal systems to assess performance and target resources for maintenance and improvement.
The management of flood defences by specifying and monitoring their performance is considered, and a recent trial in reach specification based on modelling techniques is described.     

Integrated Catchment Management Planning

Catchment management plans represent the National Rivers Authority's vision for the water environment. With the National Rivers Authority being organized by hydrological regions, the catchment is seen as the natural management unit, and catchment plans offer the means to integrate the Authority's work programme with those of other agencies. Catchment plans summarize relevant data and include an agreed action programme to optimize catchment uses, produced after wide consultation; they complement local authority statutory plans, are current for five to ten years, and will be reviewed regularly during this period. The catchment planning process is seen by the National Rivers Authority as a medium for promoting discussion, resolving conflict, assigning priorities, and setting targets by which progress on key issues can be monitored.     

The Use of Audit Surveys in River Maintenance

The use of river corridor surveys (RCS) prior to major river maintenance works is now widely accepted within the water industry as a means of integrating the requirements for nature conservation with river-management practices. This paper outlines the audit procedures introduced by the National Rivers Authority (NRA), Wessex Region.
The introduction of follow-up or audit surveys in 1988 allowed an assessment of the effectiveness of RCS in protecting and enhancing habitats. The method and results of the audit are discussed, confirming the usefulness of audit in ensuring success in the most cost-effective manner. The audit also identified training needs and failures in implementing enhancement recommendations. Audit has led to a more consistent standard of environmentally-sensitive maintenance work. A revised method for audit surveys is detailed.     

Computer Models for Quantifying the Hydro-Ecology of British Rivers

In recent years, the use of models and scoring surveys for assessing the environmental impacts associated with river-engineering works has increased. This paper discusses the circumstances in which modelling may be needed, and gives details of some of the models currently in use and under development. River corridor surveys, HABSCORE, RIVPACS (River Invertebrate Prediction and Classification System), SERCON (System for Evaluating Rivers for Conservation) and QUASAR (Quality Simulation Along Rivers) are described, and more detailed information is given on the IFIM (Instream Flow Incremental Methodology using PHABSIM), the physical habitat simulation approach being tested for the National Rivers Authority and the Ministry of Agriculture, Fisheries and Food.     

The Impact of Conservation Issues on a Sea-Defence Scheme at Pennington

The reconstruction of 8.1 km of dilapidated sea wall protecting the Hampshire coast of the Western Solent, near Lymington, presented the National Rivers Authority (Southern Region) with particular problems and substantial extra costs in coping with the needs of conservation. The resulting scheme, however, can be seen not only to have preserved but also enhanced the conservation value of its immediate surroundings in addition to the wider area of protected land.     

Controlling the Artesian Boreholes of the South Lincolnshire Limestone

This paper describes (i) a long-established, serious and growing problem in a part of the Anglian Region of the National Rivers Authority due to uncontrolled leakage of groundwater from old artesian boreholes ('wild bores') in the South Lincolnshire Limestone aquifer, and (ii) a remedial project recently undertaken by the Authority. The paper discusses (a) the nature of the problem and its implications for water resources, (b) the means employed to carry out the work, (c) environmental considerations, and (d) the results of the project.     

Evaluation of Lake Vyrnwy within the Integrated Water Supply Systems of North West Water

ABSTRACT In 1992, the National Rivers Authority published a discussion document on the National Water Resource Strategy which highlighted the future probability of a water-supply deficit in the south-east and a surplus in the north and west of England and Wales. One suggestion for rectifying this imbalance was to divert Lake Vyrnwy water which, at present, supplies Liverpool. This would allow further regulation of the River Severn, and subsequent transfer to the River Thames. Joint investigations by the National Rivers Authority and North West Water have established the implications of this diversion on the existing water resources and supply systems of North West Water.
The studies considered (a) the relationship between increased regulation releases, and reduced direct supply rates from Lake Vyrnwy, (b) the investment and operating cost implications of replacing Lake Vyrnwy supplies from sources within the southern command zone or by transfer from the northern command zone, and (c) the potential operational difficulties.
The paper describes how each of these aspects has been addressed. The results demonstrate the necessity of evaluating Lake Vyrnwy as a component of the integrated water supply systems of North West Water, and of other parts of the country.     

Environmental Impact Assessment and the Water Industry: Implications for Nature Conservation

The Nature Conservancy Council has welcomed the implementation of the EC Directive on the assessment of the effects of certain projects on the environment. This paper discusses its implications for nature conservation in fresh waters, particularly with reference to the land-drainage and flood-defence work carried out by the National Rivers Authority and its predecessors, to which the regulations SI 1217 apply. Environmental statements have been deemed necessary for only a small proportion of capital schemes initiated by the water industry since the Regulations came into force in 1988. The author has evaluated the nature-conservation content of 15 of these statements against a combined set of objective and subjective criteria. The statements examined showed a high degree of variability in length, scope, style and presentation. In general, survey and data acquisition were poorly covered. The weakest area was considered to be the evaluation and prediction of potential impacts, and this is discussed in relation to the uncertainty and complexity inherent in biological systems. The need for monitoring the accuracy of predictions after the completion of a scheme received little attention, despite its fundamental importance in improving future project design, and in extending scientific understanding.     

Barrage Developments in the Welsh Region: The Role of the National Rivers Authority in Protecting the Aquatic Environment

During recent years, barrages and marina developments have increasingly been viewed as a means of improving the aesthetic and recreational qualities of degraded urban areas, thereby encouraging inward investment. However, barrage schemes can have major implications for the National Rivers Authority's statutory responsibility for flood defence, fisheries, recreation, water quality and conservation.
The experiences gained by the National Rivers Authority's Welsh Region in its negotiations with promoters of the Tawe, Cardiff Bay and Usk barrages are presented. The paper describes the environmental safeguards secured for the Tawe barrage, together with some initial assessments of its impact on the aquatic environment following its completion in 1992. The experience gained with the Tawe barrage has contributed to a more rigorous approach being applied by the National Rivers Authority to the Cardiff Bay and Usk schemes.     

Effective Passive Treatment of Aluminium-Rich, Acidic Colliery Spoil Drainage using a Compost Wetland at Quaking Houses, County Durham

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.     

The Control and Monitoring of Discharges by Biological Techniques

Traditionally, the control of discharges to UK surface waters has been achieved using a chemical-specific approach. There are, however, benefits in also applying toxicity-based consents to effluents of complex composition.
This paper describes the approach to direct toxicity assessment of discharges being developed by the Water Research Centre for and with, the National Rivers Authority.     

Refurbishment of Control Structures on the River Avon at Strensham Lock

Three control structures at Strensham lock maintain the water level in the upstream pound of the River Avon for navigation, ecology and angling purposes. The National Rivers Authority † , which currently owns the structures, is responsible for their maintenance and for the operation of the vertical-lift sluice gates which are opened to control flooding. Construction work has recently been completed to secure the structures, which were in a poor state of repair and in danger of collapsing. The two sluice structures were completely rebuilt and the weir was modified.
The paper describes the planning, design and construction of the works, which are located within a 'site of special scientific interest'.     

Charging for Discharges and Integrated Pollution Control in Scotland

The year 1992 saw the successful implementation in Scotland of charging schemes which recover the cost of regulating authorized discharges into water and into the atmosphere. The new schemes recover from dischargers those costs of the regulatory authorities arising directly from the regulation of consented and authorized discharges. These costs were previously part of the country's overall public expenditure. The schemes operated by the river purification authorities are particularly fair because costs and charges are balanced for every individual discharger, rather than across the regulatory function as a whole. Charges therefore vary substantially both within and between river purification board areas, but a comparison of actual charges raised by the Forth River Purification Board with estimated National Rivers Authority charges indicates that the Scottish charges are generally lower. The absence of an incentive charging element contrasts with a recent recommendation of the Royal Commission on Environmental Pollution.     

Trade Effluent Control: Prospects for the 1990s

The proposed privatization of the ten regional water authorities together with the accompanying reorganization of water pollution control responsibilities between the new National Rivers Authority and Her Majesty's Pollution Inspectorate, as well as the ever tightening environmental standards for the aquatic environment emanating from Brussels and from general environmental pressures, means that dischargers of industrial effluents can expect major changes both in the cost of disposing of their effluents and in terms of the legislative controls which will restrict their content.
The paper examines the various factors which will influence the management of trade effluents in the 1990s and endeavours to give some indication of what the future holds both in terms of disposal costs and environmental regulation from the point of view of the discharger.     

Development of a Groundwater Resource Model for the Yorkshire Chalk

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.     

Controlling Diffuse Pollution of Groundwater from Agriculture and Industry

The greatest threat of contamination to groundwater resources is posed by pollutants from diffuse sources, yet legislation in the UK has until recently been focused on point sources. The problem of widespread pollution from industrial sources is described and compared with that from agriculture. The legislative controls available under the Water Resources Act 1991 are outlined, and the approach adopted by the National Rivers Authority in its Groundwater Protection Policy is discussed with respect to the concept of groundwater vulnerability.     

National Rivers Authority Initiatives in the Development of Portable Monitoring Equipment

The use of automated equipment for monitoring water quality is a concept which has received considerable impetus since the Water Act 1989 was introduced. This paper reports on two initiatives by the National Rivers Authority to develop systems for use in their role as the guardians of the water environment. Portable systems have been developed for detection of episodic pollution events and instantaneous spot measurement of water quality.
This paper outlines the principal activities of the development of the systems and their use.     

Protecting Water Resources from the Effects of Landfill Sites: Foxhall Landfill Site

This paper describes the work carried out to protect both ground and surface waters close to the Suffolk County Council Foxhall landfill sites. Monitoring of groundwater showed that a deterioration was occurring, likely to impact adversely on water quality in the adjacent stream. The National Rivers Authority expressed their concern, and measures have been introduced to eliminate this pollution risk. Contaminated groundwaters flowing towards a local watercourse are intercepted by a 'Trammel'type geotextile cut-off drain and flow to a central collection sump. Automatic monitoring of contaminant levels at this point controls the treatment and disposal options. Where quality is unacceptable for discharge to the local watercourse, the intercepted groundwaters are treated by irrigation onto the capped surface of a restored landfill. If quality remains unacceptable for discharge, further irrigation treatment or discharge to a percolation area utilizing aquifer attenuation properties is possible.     

Three Examples of the Use of Physical River Channel Models by the National Rivers Authority,Yorkshire Region†

In recent years the Yorkshire Region of the National Rivers Authority has employed the technique of physical modelling to assist in the hydraulic design of urban flood-alleviation schemes. The paper describes three examples of their use. On the River Worth at Keighley the introduction of a weir, to reduce siltation beneath a bridge, was modelled. The confluence of Batley Beck and Howley Beck in Dewsbury is located at the entrance of a culvert. A model was constructed and streamlining was introduced to improve self-cleansing and reduce head-losses. On the River Calder at Wakefield, two bridges and a weir form a complex hydraulic situation. The results of a physical model study were used to aid the calibration of a mathematical model of a much larger area. The paper reviews these model studies, indicating the costs and the likely savings resulting from reduced siltation. The paper concludes that physical modelling can provide a cost-beneficial aide to river-engineering design.     

走进历史,感受人文,体验生活——马王堆中华生态古汉城开发设想

马王堆生态古汉城的开发是在对马王堆古墓予以充分保护的基础上形成对周边地块的开发设想。文章对用地现状进行了详尽地分析，并进行了详细的项目策划、规划方案的设计及成本估算，为政府部门制定相关规划及后续开发提供了切实可靠的依据。