Estimating the sources and transport of nutrients in the Waikato River Basin, New Zealand

Alexander, Richard B.; Elliott, Alexander H.; Shankar, Ude; McBride, Graham B.

doi:10.1029/2001wr000878

Cited by 166 publications

(132 citation statements)

References 63 publications

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“…In addition, the results have provided the basis for calibration of a spatially referenced GIS-based model of pathogen loads over the whole New Zealand landscape, using the SPARROW modelling system already successfully calibrated for nutrient loads Alexander et al 2002;Elliott et al 2005).…”

Section: Funding For a Freshwater Microbiological Researchmentioning

confidence: 99%

Large-scale freshwater microbiological study: rationale, results and risks

Till¹,

McBride

Ball

et al. 2008

Journal of Water and Health

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A fifteen-month fortnightly survey of microbial health risk indicators and pathogens has been carried out at 25 freshwater recreational and water supply sites distributed throughout New Zealand, for: E. coli, Clostridium perfringens spores, F-RNA bacteriophage, somatic coliphage, human enteroviruses, human adenoviruses, Cryptosporidium oocysts, Giardia cysts, Salmonella and Campylobacter. Sites were selected to represent five geographical areas covering New Zealand and five categories of predominant environmental impact: birds, dairy farming, forestry/undeveloped, municipal, and sheep/pastoral farming. Six of the sites were also source waters for treated drinking-water supplies. Of the indicators, E. coli was detected in 99 % of all samples, with somatic coliphage being detected most of the time (89 %). Of the pathogens tested, Campylobacter and human adenoviruses were inferred to be the most likely to cause human waterborne illness to recreational freshwater users. Using data from all sites, an estimated 5 % of notified campylobacteriosis cases in New Zealand could be attributable to water contact recreation. The critical value for E. coli as an indicator of increased Campylobacter infection is in the range of 200 -500 E. coli per 100 ml. This result has been used to derive new national water quality guidelines for recreational fresh water in New Zealand.

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Section: Funding For a Freshwater Microbiological Researchmentioning

confidence: 99%

Large-scale freshwater microbiological study: rationale, results and risks

Till¹,

McBride

Ball

et al. 2008

Journal of Water and Health

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“…urban run-off, forest, and sheep and beef farms). It is assumed that the ratio of nondairy land to dairy land (b) is equivalent to that reported for the Waikato catchment in Alexander et al (2002).…”

Section: Water Qualitymentioning

confidence: 99%

Cost‐effective regulation of nonpoint emissions from pastoral agriculture: a stochastic analysis

Doole

Romera

2013

Aus J Agri & Res Econ

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Nutrient emissions from pastoral agriculture are a global cause of declining water quality. Their management is complicated through variability arising from climate and soil influences. This paper compares the implications of input-based policies and direct restrictions on leaching to achieve 10 and 20 per cent reductions in nitrogen (N) load, in the context of pasture-based New Zealand dairy farms. The most important mitigation practices on these farms are de-intensification (involving reductions in N fertiliser application and stocking rate) and the application of nitrification inhibitors. A stylised conceptual model, incorporating both sources of variability, is used to identify the implications of alternative policies. Direct restriction of estimated N leaching is the most cost-effective policy to reduce N leaching by 10 and 20 per cent. These results indicate the general insufficiency of input-based mechanisms for water quality improvement, given the low correlation between input use and leaching, possible substitution with unrestricted inputs and their failure to motivate the use of mitigation strategies. Additionally, model output indicates that inherent variability in water quality, mainly due to climate influences, can dominate the benefits of regulatory action in any given year.

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“…Agricultural and forest land management influence water quality [Pierzgalski et [Kanownik and Pijanowski 2007], which greatly contribute to water contamination in the catchment [Alexander et al 2002, Piirainen et al 2013. Therefore, an assessment of the efficiency of catchment management policy is so important [Ferraz et al 2013], especially based on increasingly better applications for modelling and forecasting ecological hazard to waters, including both climatic and anthropogenic factors [Lai et al 2013].…”

Section: Introductionmentioning

confidence: 99%