CONSIDERATIONS OF SCALE IN WATER QUALITY MONITORING AND DATA ANALYSIS<sup>1</sup>

Loftis, Jim C.; McBride, Graham B.; Ellis, Julian C.

doi:10.1111/j.1752-1688.1991.tb03130.x

Cited by 49 publications

(26 citation statements)

References 21 publications

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“…Long-term cycles in abundance can only be resolved relative to the length of the time period over which data is available (Loftis et al 1991). Thus, many trends or unpredictable behaviour detected in the initial 5.5-year period were able to be resolved into longer-term cycles when 12.5 years of data had been collected, and a five year gap in sampling resulted in a number of trends being detected that were a result of long-term cycles.…”

Section: Discussionmentioning

confidence: 94%

“…However, regardless of how successful a monitoring programme is in detecting changes in populations or communities, within the temporal scales of most monitoring programmes, it is always difficult to determine whether the changes are trends (related to anthropogenic factors) or longer-term natural cycles (Loftis et al 1991). Where specific factors e.g.…”

Section: Discussionmentioning

confidence: 98%

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Effective Long-term Ecological Monitoring Using Spatially and Temporally Nested Sampling

Hewitt

Thrush

2007

Environ Monit Assess

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Effective environmental management requires documentation of ecosystem status and changes to that status. Without long-term data, short-term natural variability can mask chronic and/or cumulative impacts, often until critical levels are reached. However, a trade-off generally occurs between sampling in space and time. This study analyses a spatially and temporally nested long-term (12 years) monitoring programme conducted on benthic macrofauna in a large harbour. Sampling was carried out at six sites for 5.5 years, after which only two sites were sampled for the next 5 years. After this period, all six sites were sampled for another 2 years. While ecology is frequently thought of being highly variable, this design was able to detect trends, and cycles, in abundance, with only around 10% of species at each site exhibiting unpredictable temporal variability. Sites exhibiting similar trends in the abundance of a species over the 12.5-year period were generally spatially contiguous, and the spatial scale of change could be assessed. Continuous sampling at two sites identified whether changes in unsampled sites were related to long-term cycles. Moreover, this sampling provided a long-term background of temporal fluctuations against which to assess the ecological significance of observed changes.

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Section: Discussionmentioning

confidence: 94%

Section: Discussionmentioning

confidence: 98%

Effective Long-term Ecological Monitoring Using Spatially and Temporally Nested Sampling

Hewitt

Thrush

2007

Environ Monit Assess

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“…Other approaches include trend analysis techniques, Bayes detision theory and extended applications of optimization techniques Alpaslan et al, 1992;Liebetrau, 1979;Lettenmaier, 1979;Mueller, 1989;Richards, 1989;Lachance et al, 1989;Loftis et al, 1991). Whitfield (1988) For each of these goals of monitoring, Whitfield stresses the selection of different sampling frequencies to maximize the information gain via sampling.…”

Section: Selection Of Temporal Frequenciesmentioning

confidence: 98%

Water Quality Monitoring and Network Design

Harmancioğlu¹,

Ozkul²,

Alpaslan³

1998

Environmental Data Management

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Abstract. In recent years, shortcomings of both the available data on water quality and the existing networks have led designers to focus more critically on the design procedures used. Within this respect, this chapter addresses the prevailing problems associated with water quality monitoring networks and discusses current attempts towards improvement of existing networks. IntroductionIn recent years, problems observed in available water quality data and shortcomings of current monitoring networks have led designers and researchers to focus more critically on the design procedures used. Developed countries have feit the need to assess and redesign their monitoring programs after having run their networks for more than 20 years. Developing countries are still in the process of expanding their rather newly initiated networks; yet they also find it necessary to evaluate what they have accomplished so far and how they should proceed from this point on. In both cases of the developed and the developing countries, the major problem is that there are no universally confirmed guidelines to follow in the assessment and design of water quality monitoring networks. Upon this need, significant amount of research has been initiated to evaluate current design procedures and investigate effective means of irnproving the efficiency ofexisting networks (Ward et al., 1990;Chapman, 1992;Adriaanse et al, 1995;Ward, 1996;Timmerman et al. 1996;Niederlander et al., 1996;Dixon and ChisweIl, 1996).At present, the adequacy of collected water quality data and the performance of existing monitoring networks have been seriously evaluated for two basic reasons. First, an efficient information system is required to satisfy the needs of water quality management plans and to aid in the decision making process. Second, this system has to be realized under the constraints of limited financial resources, sampling and analysis facilities, and manpower.Despite all efforts made on monitoring ofwater quality, the current status of existing networks shows that the accruing benefits are low.

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“…This information was needed at several temporal and spatial scales, which in¯uence monitoring design and the choice of data analysis methods (Loftis et al, 1991). Temporal scales included instantaneous, daily, seasonal (or dierent¯ow events) and annual (or all events).…”

Section: Monitoring Designmentioning

confidence: 99%

Attributes and uncertainty of dissolved zinc data from a mined catchment

Caruso

1999

Hydrol. Process.

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Abstract:This study evaluated the attributes and uncertainty of non-point source pollution data derived from synoptic surveys in a catchment aected by inactive metal mines in order to help to identify and select appropriate methods for data analysis/reporting and information use. Dissolved zinc data from the Upper Animas River Basin, Colorado, USA, were the focus of the study. Zinc was evaluated because concentrations were highest relative to national water quality criteria for brown trout, and zinc had the greatest frequency of criteria exceedances compared with other metals. Data attributes evaluated included measurement and model error, sample size, non-normality, seasonality and uncertainty. The average measurement errors for discharges, concentrations and loadings were 0 . 15, 0 . 1 and 0 . 18, respectively. The 90 and 95% coecients of con®dence intervals for mean concentrations based on a sample size of four were 0 . 48 and 0 . 65, respectively, and ranged between 0 . 15 and 0 . 23 for sample sizes greater than 40. Aggregation of data from multiple stations decreased the con®dence intervals signi®cantly, but additional aggregation of all data increased them as a result of increasing spatial variability. Unit area loading data were approximately log-normal. Concentration data were right-skewed but not log-normal. Dierences in median concentrations were appreciable between snowmelt and both storm¯ow and base¯ow, but not between storm¯ow and base¯ow. Dierences in unit area loadings between all¯ow events were large. It was determined that the average concentration and unit area loading values should be estimated for each¯ow event because of signi®cant seasonality. Time weighted values generally should be computed if annual information is required. The con®dence in average concentrations and unit area loadings is dependent on the computation method used. Both concentrations and loadings can be signi®cantly underestimated on an annual basis when using data from synoptic surveys if the ®rst¯ush of contaminants during the initial snowmelt runo period is not sampled. The ambient standard for dissolved zinc for all events was estimated as 1600 mg l À1 using the 85th percentile of observed concentration data, with a 90% con®dence interval width of 200 mg l À1 .

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CONSIDERATIONS OF SCALE IN WATER QUALITY MONITORING AND DATA ANALYSIS¹

Cited by 49 publications

References 21 publications

Effective Long-term Ecological Monitoring Using Spatially and Temporally Nested Sampling

Effective Long-term Ecological Monitoring Using Spatially and Temporally Nested Sampling

Water Quality Monitoring and Network Design

Attributes and uncertainty of dissolved zinc data from a mined catchment

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CONSIDERATIONS OF SCALE IN WATER QUALITY MONITORING AND DATA ANALYSIS1

Cited by 49 publications

References 21 publications

Effective Long-term Ecological Monitoring Using Spatially and Temporally Nested Sampling

Effective Long-term Ecological Monitoring Using Spatially and Temporally Nested Sampling

Water Quality Monitoring and Network Design

Attributes and uncertainty of dissolved zinc data from a mined catchment

Contact Info

Product

Resources

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CONSIDERATIONS OF SCALE IN WATER QUALITY MONITORING AND DATA ANALYSIS¹