Streamflow and Water Temperature
• Streamflow is a measure of how much
water passes a point in the stream over time. Water temperature
is a measure of the hotness or coldness of the water in a stream.
Both are important components of water-quality assessments and
affect physical, chemical, and biological characteristics of
streams. Streamflow affects the transport of chemicals, habitat
characteristics, and biological communities in a stream. Water
temperature can affect the types of biological communities and
chemical reactions in streams. All components (physical, chemical,
biological) in a stream can be influenced by changes in the hydrologic
regime (characteristic behavior and quantity of streamflow).
Streamflow and water temperature can be altered as urban intensity
in a basin increases. In this study, patterns of streamflow and
water temperature were used to compare sites along a gradient
of urban intensity from low to high and to determine the relation
to other physical, chemical, and biological factors.
What we measured:
• Stage height (height of the water
in the stream) was used to measure streamflow.
• Water temperature at hourly
When we sampled:
• Streamflow and water temperature
were measured continuously in each stream for approximately a
one year period, although the length of record may vary among
streams within and among study areas.
Field collection protocols:
• Transducers were used to measure
stage height and water temperature.
• Transducers were place
in each stream near the stream reach that was sampled
for habitat and biological communities.
• Transducers were
checked and data downloaded on a monthly
to bimonthly basis.
Quality assurance and control:
• Stage data from the pressure transducer
used in studies conducted in 2003 and 2004 had an accuracy of ± 0.036
meters (0.12 feet) which does not meet the USGS standard for
accuracy of stage data which is ± 0.003 meters (0.01 feet)
(Sauer, 2002). Although the stage data used in this study is
not the level of accuracy normally seen from USGS stage data,
the stage data meets the purpose of this study which was to look
at patterns of flow variability in streams.
What this data represent:
• Stage data is used to characterize
changes in streamflow due to urbanization using measures of overall
variability, frequency of change in streamflow (flashiness),
and duration of high and low flow conditions after McMahon and
• Temperature data will be
used to characterize changes in water temperature due
to urbanization using measures of daily water temperature,
variability in daily temperature, and relation to changes
McMahon, Gerard, Bales, J.D., Coles J.F.,
Giddings, E.M.P., and Zappia, Humbert, 2003, Use of stage data
to characterize hydrologic conditions in an urbanizing environment:
Journal of the American Water Resources Association, vol. 39,
no. 6., p. 1529-1546.
Sauer, V.B., 2002, Standards for the analysis
and processing of surface water data and information using electronic
methods: U.S. Geological Survey Water-Resources Investigations
Report 01- 4044, 91 p.