Water quality indices

Given the present constraints on capital expenditure for water quality improvements, it is essential that best management practices be adopted whenever possible. This research provides an evaluation of existing practices in use within the water industry for surface water quality classification and assesses water quality indices as an alternative method for monitoring trends in water quality. To this end, a new family of indices have been developed and evaluated and the management flexibility provided by their application has been examined. It is shown that water-quality indices allow the reduction of vast amounts of data on a range of determinand concentrations, to a single number in an objective and reproducible manner. This provides an accurate assessment of surface water quality which will be beneficial to the operational management of surface water quality. Previously developed water quality indices and classifications are reviewed and evaluated. Two main types of index are identified: biotic indices and chemical indices. The former are based exclusively upon biological determinands/indicators and are used extensively within the United Kingdom in the monitoring of surface water quality. The latter includes a consideration of both physico-chemical and biological determinands, but with an emphasis on the former variables. Their use is still the subject of much controversy and discussion. Four main approaches to the development of chemical indices can be identified in accordance with the aims and objectives of their design. Those developed for general application are known as General Water Quality Indices (WQIs) or Indices of Pollution, with the latter based predominantly upon determinands associated with man-made pollution. Those which reflect water quality in terms of its suitability for a specific use are termed use-related; whilst planning indices are those which attempt to highlight areas of high priority for remedial action on the basis of more wide-ranging determinands. The derivation and structure of previously developed indices have been evaluated and the merits and strengths of each index assessed. In this way, nine essential index characteristics were identified, including the need to develop an index in relation to legal standards or guidelines. In addition it was recognised that one requirement of an index should be to reflect potential water use and toxic water quality in addition to general quality as reflected by routinely monitored determinands. The development of river quality classifications within the United Kingdom is reviewed and the additional management flexibility afforded by the use of an index evaluated by comparing the results produced by the SOD (1976) Index with those of the National Water Council (NWC, 1977) Classification. The latter classification is that presently used to monitor water quality in Britain. The SOD Index was found to be biased towards waters of high quality and provided no indication of potential water use or toxic water quality. Nevertheless, it displayed a number of advantages over the NWC Classification in terms of the operational management of surface water quality. It was therefore decided to develop a new family of water quality indices, each based upon legally established water quality standards and guidelines for both routinely monitored and toxic determinands and each relating water quality to a range of potential water uses, thereby indicating economic gains or losses resulting from changes in quality. Four stages in the development of a water quality index are discussed: determinand selection; the development of determinand transformations and weightings; and the selection of appropriate aggregation functions. Four separate indices have been developed as a result of this research. These may be used either independently or in combination with one another where a complete assessment of water quality is required. The first of these is a General Water Quality Index (WQI) which reflects water quality in terms of a range of potential water uses. This index is based upon nine physico-chemical and biological determinands which are routinely monitored by the water authorities and river purification boards of England, Wales and Scotland. The second, the Potable Water Supply Index (PWSI) is based upon thirteen routinely monitored determinands, but reflects water quality exclusively in terms of its suitability for use in potable water supply (PWS). The two remaining indices, the Aquatic Toxicity (ATI) and Potable Sapidity (PSI) Indices are based upon toxic determinands such as heavy metals, pesticides and hydrocarbons which are potentially harmful to both human and aquatic life. Both indices are use-related, the former reflecting the suitability of water for the protection of fish and wildlife populations; the latter, the suitability of water for use in PWS. Each index is based upon nine and twelve toxic determinands respectively. These indices were developed in as objective and rigorous a manner as possible, utilising an intensive interview and questionnaire programme with members of both the water authorities and river purification boards. Rating curves were selected as the best way in which individual determinand concentrations could be transformed to the same scale. The scales selected for the WQI and PWSI are 10 - 100 and 0 - 100 respectively, whilst those of the ATI and PSI are 0 - 10. Each has been sub-divided in such a way as to indicate not only water quality, but also possible water use. Thus, the indices reflect both current and projected changes in the economic value of a water body which would occur as a result of the implementation of alternative management strategies. The curves were developed using published water quality standards and guidelines relating to specific water uses. Therefore, they contain information on standards which must be adhered to within the United Kingdom and this adds a further dimension to their management flexibility. Determinand weightings indicating the emphasis placed by water quality experts upon individual determinands were assigned to the determinands of the WQI and PWSI. However, weightings were omitted from the ATI and PSI due to the sporadic nature of pollution events associated with these determinands. These vary spatially and temporally, both in concentration and in terms of which determinand is found to be in violation of consent conditions. Therefore, on a national scale, no one determinand could be isolated as being more important than any other. Three aggregation formulae were evaluated for use within the developed indices: the weighted and unweighted versions of an arithmetic, modified arithmetic and multiplicative formulation. Each index was applied to data collected from a series of water quality monitoring bodies covering a range of water quality conditions. In each instance, the modified arithmetic formulation was found to produce index scores which agreed most closely with a predetermined standard, normally the classifications assigned using the NWC classification. In addition, this formulation produced scores which best covered the ascribed index range. However, the multiplicative unweighted formulation was retained for use within the ATI and PSI for the detection of zero index scores, i.e. when concentrations in excess of legal limits were recorded for these toxic determinands. The results from these studies validate the ability of each index to detect fluctuations in surface water quality. Therefore, the utility of the developed indices for the operational management of surface water quality was effectively demonstrated and the flexibility and advantages of an index approach in providing additional information upon which to base management decisions was highlighted. Amongst these advantages was the ability of an index to provide information upon which potential cost-benefit assessments could be made in relation to either spatial or temporal changes to surface water quality. Finally, the need for both general and use-related indices was investigated and found to be an advantage, although not strictly necessary, because the WQI efficiently recorded the range in quality conditions associated with the use of water in potable water supply

Routine administration of Health Related Quality of Life (HRQoL) and needs assessment instruments to improve psychological outcome: a systematic review

Background. Routine administration of Health Related Quality of Life (HRQoL) and needs assessment instruments has been advocated as part of clinical care to aid the recognition of psychosocial problems, to inform clinical decision making, to monitor therapeutic response and to facilitate patient-doctor communication. However, their adoption is not without cost and the benefit of their use is unclear. Method. A systematic review was conducted. We sought experimental studies that examined the addition of routinely administered measures of HRQoL to care in both psychiatric and non-psychiatric settings. We searched the following databases: MEDLINE, EMBASE, CINAHL, PsycLIT and Cochrane Controlled Trials Register (to 2000). Data were extracted independently and a narrative synthesis of results was presented. Results. Nine randomized and quasi-randomized studies conducted in non-psychiatric settings were found. All the instruments used included an assessment of mental well-being, with specific questions relating to depression and anxiety. The routine feedback of these instruments had little impact on the recognition of mental disorders or on longer term psychosocial functioning. While clinicians welcomed the information these instruments imparted, their results were rarely incorporated into routine clinical decision making. No studies were found that examined the value of routine assessment and feedback of HRQoL or patient needs in specialist psychiatric care settings. Conclusions. Routine HRQoL measurement is a costly exercise and there is no robust evidence to suggest that it is of benefit in improving psychosocial outcomes of patients managed in non-psychiatric settings. Major policy initiatives to increase the routine collection and use of outcome measures in psychiatric settings are unevaluated

Routinely administered questionnaires for depression and anxiety : systematic review

Objectives To examine the effect of routinely administered psychiatric questionnaires on the recognition, management, and outcome of psychiatric disorders in non-psychiatric settings. Data sources Embase, Medline, PsycLIT, Cinahl, Cochrane Controlled Trials Register,and hand searches of key journals. Methods A systematic review of randomised controlled trials of the administration and routine feedback of psychiatric screening and outcome questionnaires to clinicians in non-psychiatric settings. narrative overview of key design features and end points, together with a random effects quantitative synthesis of comparable studies. Main outcome measures Recognition of psychiatric disorders after feedback of questionnaire results; interventions for psychiatric disorders and outcome of psychiatric disorders. Results Nine randomised studies were identified that examined the use of common psychiatric instruments in primary care and general hospital settings. Studies compared the effect of the administration of these instruments followed by the feedback of the results to clinicians, with administration with no feedback. Meta-analytic pooling was possible for four of these studies (2457 participants), which measured the effect of feedback on the recognition of depressive disorders. Routine administration and feedback of scores for all patients (irrespective of score) did not increase the overall rate of recognition of mental disorders such as anxiety and depression (relative risk of detection of depression by clinician after feedback 0.95, 95% confidence interval 0.83 to 1.09). Two studies showed that routine administration followed by selective feedback for only high scores increased the rate of recognition of depression (relative risk of detection of depression after feedback 2.64, 1.62 to 4.31). This increased recognition, however, did not translate into an increased rate of intervention. Overall, studies of routine administration of psychiatric measures did not show an effect on patient outcome. Conclusions The routine measurement of outcome is a costly exercise. Little evidence shows that it is of benefit in improving psychosocial outcomes of those with psychiatric disorder managed in non-psychiatric settings

Patterns of Late Cenozoic exhumation deduced from apatite and zircon U-He ages from Fiordland, New Zealand

New apatite and zircon (U-Th)/He ages from the Fiordland region of New Zealand's South Island expand on earlier results and provide new constraints on patterns of Late Cenozoic exhumation and cooling across this region. Zircon (U-Th)/He cooling ages, in combination with increased density of apatite ages, show that in addition to a gradual northward decrease in cooling ages that was seen during an earlier phase of this study, there is also a trend toward younger cooling ages to the east. Distinct breaks in cooling age patterns on southwestern Fiordland appear to be correlated to the location of previously mapped faults. The northward decrease in ages may reflect asynchronous cooling related to migration in the locus of exhumation driven by subduction initiation, or it may reflect synchronous regional exhumation that exposed different structural levels across Fiordland, or some combination of these effects. In either case, differential exhumation accommodated by major and minor faults that dissect Fiordland basement rocks apparently played an important role in producing the resulting age patterns

REVENUE RISK AND FISHERY CHOICE WITH LINEAR-EXPONENTIAL UTILITY: AN APPLICATION TO BERING SEA/ALEUTIAN ISLANDS TRAWL FISHERIES

A discrete choice model of 1991-96 trawl groundfish fishery participation in the Bering Sea/Aleutian Islands region is developed and estimated. The model fits well, with strong risk and seasonal effects. Notably, the model uses routinely-collected data, suggesting this type of analysis can be a regular part of the management process.Resource /Energy Economics and Policy,

TOWARD EFFICIENT BYCATCH MANAGEMENT IN MULTISPECIES FISHERIES: A NONPARAMETRIC APPROACH

Linear programming-based models of individual multispecies groundfish operations in the Bering Sea/Aleutian Islands area are developed and applied to the question of determining efficient bycatches. The policy tool is halibut quotas, which restrict the bycatch of halibut and also induce changes in the target species catch composition and bycatch of other prohibited species. Efficient quotas can be interpolated from the locus of shadow values for discrete halibut quotas relative to the opportunity cost of prohibited species bycatch induced by the policy-set quotas on halibut bycatch. Because of information limitations intrinsic to fisheries management, the efficient halibut quotas are considered in the context of ranges of marginal value and marginal opportunity cost developed using short- and long-run groundfish fishery models and standard error estimates of opportunity cost.Resource /Energy Economics and Policy,

Oscillations of Cantilevered Tubular Steel Piles in Current Flow

A laboratory experiment was conducted in a 20 m flume tank at Plymouth University to investigate the movement of, and forces applied to, a pair of in-line cantilevered piles. 2-minute tests were run with a 64 mm diameter upstream pile and downstream piles of 64 mm, 40 mm and 30 mm. Current velocities ranging from 0.1 to 0.9 m/s and spacings between the piles of 3 to 10 diameters were varied along with the downstream pile diameter. Initially, tests with all 3 piles on their own were conducted and the results showed a close comparison with the theoretical cross-flow oscillation frequency and the measured cross-flow oscillation frequency of the solitary pile. Similarities between the theoretical and measured steady drag forces were not identified but a significant relationship between steady drag force on the downstream pile and spacing was discovered. The results indicated that when the spacing was small, approximately 3 to 4 diameters, the downstream pile experienced more drag force than the upstream. The force steadily decreased until it appeared to level out around 9 to 10 diameters away. Analysis of the cross-flow oscillations of the downstream pile revealed that the 64 mm pile oscillated with a frequency close to the theoretical at all spacings and flow velocities. Whereas, the 40 mm and 30 mm piles oscillated with frequencies less than the theoretical, at all spacings and flow velocities. Despite the solitary 40 mm and 30 mm piles oscillating at the theoretical frequency. This demonstrated that the oscillation frequency of the downstream pile was governed by the size and therefore the vortex shedding frequency of the upstream pile

Social encounter networks : collective properties and disease transmission

A fundamental challenge of modern infectious disease epidemiology is to quantify the networks of social and physical contacts through which transmission can occur. Understanding the collective properties of these interactions is critical for both accurate prediction of the spread of infection and determining optimal control measures. However, even the basic properties of such networks are poorly quantified, forcing predictions to be made based on strong assumptions concerning network structure. Here, we report on the results of a large-scale survey of social encounters mainly conducted in Great Britain. First, we characterize the distribution of contacts, which possesses a lognormal body and a power-law tail with an exponent of −2.45; we provide a plausible mechanistic model that captures this form. Analysis of the high level of local clustering of contacts reveals additional structure within the network, implying that social contacts are degree assortative. Finally, we describe the epidemiological implications of this local network structure: these contradict the usual predictions from networks with heavy-tailed degree distributions and contain public-health messages about control. Our findings help us to determine the types of realistic network structure that should be assumed in future population level studies of infection transmission, leading to better interpretations of epidemiological data and more appropriate policy decisions