Xylem SonTek FlowTracker2, User Manual

Page: 78 / 308

SonTek – a Xylem brand
FlowTracker2 User’s Manual (January 2019)
77
Method Measurement Depth Mean Velocity Equation
None No velocity measurement
V
mean
= CF * V
adjacent
Mean velocity is based on the velocity from the adjacent
station(s), multiplied by a user-specified correction factor.
This method is used when velocity measurements cannot be
made or with the Japanese method.
Input V User input velocity
V
mean
= V
input
User enters an estimated velocity value. This method is
used when velocity measurement is not possible, most
commonly due to weed growth along a riverbank.
Methods involving more than one measurement can be done in either direction (from
surface to the bottom or from the bottom towards the surface).
Method None 5.1.3.1
The method None is used in a number of different scenarios from assigning zero velocity
to channel banks, stations where no measurements are possible to Japanese method
where the measurement section is wider than 10m.
a) Channel Banks
i). Edges describing the left or Right bank of a channel,
ii). Island Edges describing the banks of island\s,
iii). The method
None is assigned automatically for Edges and Island Edges by
the software.
b) Station Measurement not Possible
i). The measuring site conditions do not allow velocity measurement (perhaps
due to weed growth),
ii). Velocity for this station is based on the mean station velocity from the adjacent
station(s) with velocity measurements multiplied by the user-specified
correction (
CF ) factor for this station.
c) Japanese Method
i). Japanese measuring technique for measurement sections wider than 10m
require velocity measurements only at every second station,
ii). A velocity method of “Depth Only” is assigned to None velocity stations.
Vertical Velocity Curve 5.1.3.2
The Vertical Velocity Curve method is a series of point velocity measurements that are
well distributed between the water surface and channel bed. Normally observation is
made at 0.1 depth increments between 0.1 and 0.9 of the total water depth. Point
velocity measurements at the standard 0.2, 0.6 and 0.8 depths are required to compare
the vertical velocity curve method against standard methods.