YSI SonTek RiverSurveyor, System Manual

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SonTek/YSI Inc
RiverSurveyor System Manual (May 1, 2007)
171
Appendix F. Velocity Indexing and FlowPack
Velocity-Index ratings provide a relationship between the true mean velocity of a river (which is
used to determine the flow) and the velocity measured by an installed current meter (e.g., Argo-
naut-SL or SW) located at the site. Measurements from RiverSurveyor and/or FlowTracker sys-
tems are used together with data from the installed current meter in the derivation of a rating.
Velocity-Indexing is typically used at sites where traditional methods of relating the stage to the
flow (commonly called Stage-Discharge) cannot be used because of complex flow conditions.
The quality of a Velocity-Index rating is generally dependent on the number of measurements
made and the range of conditions (different stages and velocities) over which these measure-
ments were made.
How Do I Build a Velocity-Index Rating?
Outlined below is a basic procedure for building a data set of measurements for the development
of a Velocity-Index rating that can be calculated using SonTek’s
FlowPack software program.
1. A current meter installed at the site records continuous measurements of velocity and stage.
2. Individual measurements are made at the site using a flow measurement device such as a
RiverSurveyor or FlowTracker system. This flow data are gathered at different times, stages,
and flows to provide as wide a range of conditions as possible.
3. Site information and the cross-section geometry are entered into FlowPack .
4. The data from the installed current meter are entered into FlowPack .
5. The data from the flow measurement device are entered into FlowPack .
6. FlowPack matches the RiverSurveyor/FlowTracker’s measurements with the installed cur-
rent meter’s simultaneous measurements. This creates a series of records of discharge, stage,
and measured velocity at different times.
7. FlowPack correlates and analyzes this data to determine the best form of the relationship be-
tween the velocity measured by the current meter and the mean velocity of the river.
8. FlowPack generates a report that graphically displays this relationship (
Figure F-1
).
How Does FlowPack Assist in the Velocity-Index Rating Process?
FlowPack software lets you create easy to develop and interpret Velocity-Index ratings. This
makes the entire analysis and data reporting process friendlier and faster with easy to use tools
that store flow, velocity, and stage measurements – all through one program. Comprehensive re-
ports help you make better, more informed decisions. The tools provided in
FlowPack serve to
complement and enhance the data collected using a RiverSurveyor system, especially for histori-
cal record-keeping purposes.
FlowPack has the following features and capabilities:
•
Simplified measurement storage and data review.
•
Storage of multiple sites and ratings.
•
Imports data from a variety of sources including SonTek’s stage and discharge instruments
(e.g., Argonaut-SL, Argonaut-SW, FlowTracker, RiverSurveyor) and similar devices.
•
Collates and appends measurements.
•
Develops Stage-Area relationships; computes Velocity-Index ratings.
•
Outputs analysis results.
•
Multi-language support.
For more information about FlowPack , refer to the program’s documentation or contact SonTek.
A free evaluation version of FlowPack is available on the SonTek website: