Water colour and clarity of New Zealand rivers under baseflow conditions
作者:
RobertJ. Davies‐Colley,
MurrayE. Close,
期刊:
New Zealand Journal of Marine and Freshwater Research
(Taylor Available online 1990)
卷期:
Volume 24,
issue 3
页码: 357-365
ISSN:0028-8330
年代: 1990
DOI:10.1080/00288330.1990.9516430
出版商: Taylor & Francis Group
关键词: water colour;water clarity;appearance;suspended solids;turbidity;optical properties;New Zealand rivers
数据来源: Taylor
摘要:
Visual clarity and apparent colour (hue) of 96 New Zealand rivers was investigated under baseflow (< median flow) conditions. Visual clarity, measured as the horizontal sighting range of a black disk, ranged 40‐fold from 0.25 to 10.75 m. Only 7% of the clarity observations were “low” (black disk range < 1.2 m), whereas 31% were “high” (> 4 m). Visual clarity was strongly related to nephelometric turbidity (r= ‐0.88) but was less strongly related to suspended solids concentration (r= ‐0.77), even though scattering and absorption of light by suspensoids accounted for most (87 % on average) of overall light beam attenuation. Hue, as described in the field while viewing black disk range, varied from the blues of optically pure water to orange in waters with high concentrations of organic material, particularly yellow substance. There was a weak tendency for clear river waters to be blue‐green in hue whereast turbid waters were more typically yellow‐coloured.
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