Assessing the National Streamflow Information Program (2004) / Chapter Skim
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6 Contributions of NSIP to River Science
6 Contributions of NSIP to River Science
Pages 120-134
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From page 120... ...
These processes are sensitive to land-use change and climate change; therefore, one key way that in which the National Streamflow Information Program (NSIP) can support river science is by providing information on how human activities influence key processes that alter a river system relative to some minimally disturbed "reference" conditions (such as might be provided by the sentinel watershed element of NSIP; see Chapter 3)
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From page 121... ...
has a critical role to play, through streamgaging and more comprehensive river process studies, in water resources prediction and in support of river management in the coming decades. The committee was asked to address the following statement of task: How does the National Streamflow Information Program support river science, and can it support an integrated river science program in addition to its operational objectives?
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From page 122... ...
One of the strongest examples of this is the field of fluvial geomorphology, which has developed with strong support of USGS streamflow information and strong scientific leadership from within the USGS. For example, the term "hydraulic geometry" refers to the changes in hydraulic variables (width, depth, velocity)
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From page 123... ...
A limitation of this data source is that USGS gaging stations are chosen to have particular channel characteristics, such as the existence of a control section that will ensure a unique rating curve. The channel characteristics of streamgage locations may thus not be representative of randomly selected locations at any point along the entire length of a stream or river.
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From page 124... ...
USGS streamflow data provide an important data set that can be used to evaluate flow resistance, provided stream gradient is known. Grain size information is also essential geomorphic information that is required both for geomorphic studies of channel morphology, sediment transport, and channel changes and for many ecological studies as well.
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From page 125... ...
They combined empirically derived relations between flow and tree mortality with a hydraulic model of the Gunnison River bottomland to generate Figure 6-3, a mortality response surface expressed in terms of key streamflow variables. Such a model provides park managers a tool for determining how upstream reservoir operations might be manipulated
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From page 126... ...
As another example, innumerable studies are conducted by state and federal agencies throughout the United States to evaluate minimum instream flows for fish using techniques of quantifying time series of hydraulic habitat conditions, and these almost always require the availability of high-quality flow data (IFC, 2002)
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From page 127... ...
Ecological studies also require information at ungaged locations, indicating the need for development of streamflow estimation and geomorphic estimation procedures. Streamflow Information Needs for Surface Water-Groundwater Interaction Studies The hyporheic zone is the subsurface interface between stream water and the groundwater interacting with it (Figure 6-4)
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From page 128... ...
128 Assessing the National Streamflow Information Program FIGURE 6-4 The hyporheic zone. Note the "envelope" of water under the stream that is active with respect to water fluxes and mixing and geochemical processes.
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From page 129... ...
For example, inexpensive pressure transducers or thermistors could be installed adjacent to small headwater streams to monitor directional changes in groundwater flow relative to the stream and the extent to which periodic flooding affects the fundamental hydraulics associated with floodplains. The data output from these devices could be sampled remotely along with stream stage.
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From page 130... ...
Both of these needs can be met only if there is an extensive streamflow gaging network that has representative coverage of the range of climatic and watershed characteristics across the United States. This section reviews the streamflow information available at NSIP gages and its suitability for the needs of the river science community as described above.
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From page 131... ...
· Unit discharges. In the current NWIS water information dissemination program, instantaneous discharges that provide essential hydrographic and peak flow information for streams are stored for 30 days after an event occurs.
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From page 132... ...
Collected but unreported information includes data on channel cross sections collected at gaging stations, bed particle size information, and flood survey data. Importance of the Non-base NSIP Network for River Science In previous parts of this document, we evaluate the core, or base, NSIP network.
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From page 133... ...
2.0 1.8 R2 = 0.90 (Excluding Soquel and Corralitos) 1.6 MAGNITUDE INTERVAL 1.4 FLOOD 1.2 ÑO NI RECURRENCE EL 1.0 Soquel 5-YEAR Corralitos A 0.8 Line of equal strength El Niño and non-El Niño Floods NORMALIZED WITH 0.6 32 34 36 38 40 42 LATITUDE FIGURE 6-6coastal 133 38 California Relationship between normalized Elet flood magnitude and latitude for streams.
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From page 134... ...
Valuable information is contained in crest stage data, slope-area data from flood studies, and gaging station channel geometry and bed sediment characteristics. The USGS should to continue to work on explicitly linking surface water to groundwater.
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