A Method for Managing River Abstractions and Protecting the Environment

A n I mproved method has been developed to assess and control the quantity of water available to river abstractors. The methodology quantifies the sensitivity of the river environment to abstraction by a weighting system, and uses this to establish, on a subcatchment basis, maximum permissible volumes of abstraction and minimum permissible river flows. Guidelines developed from the methodology have been used as the basis for determining applications for abstraction licences in North Yorkshire, before being extended to cover the rest of the Yorkshire Water area.     

Lessons Learned from the UN Water Decade

The United Nations Drinking Water Supply and Sanitation Decade ran from 1981 to 1990. Much was achieved, but the target of a safe water supply and adequate sanitation for all was not. However, many helpful lessons of experience were derived, and these should guide work in this sector over the next several decades. The paper briefly reviews the achievements of the decade, and considers the lessons learned.     

Orthophosphate Concentrations in the River Thames

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.     

The performance of a well insulated house heated by an air-water heat pump

This paper describes the performance of a highly insulated house operated under simulated occupancy and heated by an air-water heat pump during 1978–80. The house, which was one of four BRE low energy house laboratories, was heated continuously to 20°C.

Although underfloor heating coils were employed. (in order to provide a low condensing temperature for the heat pump) the control of internal temperatures was largely satisfactory being within ± 2°C of the mean value on over 85% of occasions.

The seasonal coefficient of performance of the heat pump for space and hot water heating was 2.3 which in primary energy terms corresponds to a natural gas boiler of about 70% efficiency. The heat demand of the dwelling at ?1°C was 3.8 kW which was close to the expected value and the heat pump required backup heating only during some defrosts. The backup heating system was used in the true supplementary mode only on 2 days during the winter of 1978/79.     

Strategies for Handpump Water Supply Programmes in Less-Developed Countries

ABSTRACT Community water supply programmes in developing countries frequently utilize wells or boreholes equipped with handpumps as the technology of choice. Whilst simple targets concerning numbers of wells to be drilled or villages to be served are often prominent, the wider objectives of such programmes are rarely expressed in quantified terms and, as a consequence, programme impact is often disappointing as well as difficult to evaluate. Because objectives are not clear, programme strategy fails to include all the issues and activities which are necessary to achieve the maximum beneficial impact on participating communities. In the paper, target objectives, checklists of programme activities, and staffing requirements are proposed. The subject of programme impact is briefly discussed, and a realistic approach to programme evaluation is outlined. The paper is intended both as an aid to project planners and as a guide to managers and evaluators of existing well-handpump programmes.     

Guidelines for Greywater Re-Use: Health Issues

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.     

The Sea-Defence Value of Salt Marshes: Field Evidence From North Norfolk

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.     

Groundwater Nitrate Concentrations from the Old Chalford Nitrate-Sensitive Area, West Oxfordshire

This paper, describes nitrate concentrations in a groundwater catchment currently designated as a nitrate-sensitive area. Although the scheme has been operational for two years, groundwater nitrate concentrations have regularly exceeded the EC maximum admissible concentration of 11.3 mg/1 NO₃-N (50 mg/1 NO₃) from sources draining both arable and grassland management regimes. Nitrate levels from arable areas tend to produce a seasonal pattern of winter leaching and summer uptake, whilst no such pattern or fluctuation is observed from grassland areas. Four processes are defined which regulate nitrate inputs to the saturated zone of the Great Oolite aquifer: (i) availability of 'free'nitrogen, (ii) variations in nitrogen uptake, (iii) leaching of nitrates from the soil environment, and (iv) limited atttenuation within the unsaturated zone.     

The Pre-design of Berenplaat Water-Treatment Works, Rotterdam: Additional Processes to Achieve Biologically Stable Water

Biological regrowth in a water distribution system can be avoided by either maintaining a free chlorine residual to suppress growth or controlling conditions which may support growth, or by a combination of both. Micro-organisms will grow in water only if nutrients are present in sufficient amounts; conversely the reduction of biodegradable nutrients in water is vitally important in controlling the regrowth of microorganisms and zooplankton in the distribution system. The measurement of assimilable organic carbon has been developed as a way of evaluating the concentration of biodegradable material which is available to support such biological growth.
This paper describes the pilot-plant and full-scale studies carried out at the Berenplaat water-treatment works, Rotterdam to (a) improve disinfection, (b) eliminate the formation of trihalomethanes and other halogenated compounds formed by chlorination, and (c) reduce the final water assimilable organic carbon concentrations to very low levels, so that a high degree of biological stability can be maintained in the distribution system.     

The Use of Biosolids and Other Organic Substances in the Creation of Soil-Forming Materials

This paper describes an experiment which was carried out at a landfill site in north Lincolnshire to investigate the use of biosolids and other organic materials in soil formation. The following organic amendments were incorporated into the surface of the on-site geological clay to form 'topsoil'treatments: (i) nil, (ii) biosolids (digested cake), (iii) waste peat/compost, and (iv) composted green waste. The biosolids were applied at a rate of 70 tDS/ha and all the organic materials were incorporated to a depth of 150 mm. The organic amendments reduced the topsoil bulk density and increased plant available water supply and soil water infiltration rates. Topsoil organic matter, total nitrogen and extractable phosphorus concentrations, biomass nitrogen, readily mineralisable organic nitrogen and soil respiration rates were also increased. Additionally, the biosolids application increased topsoil aggregate stability and soil surface strength.