Edit stage discharge measurements
By stage-discharge data is meant condensed results of flow velocity measurements, i.e. stages and discharges, to be used for the establishment of stage-discharge relations.
Discharge rating curves in hymosare of the following types:
- simple stage-discharge relation
- stage-discharge relation with unsteady flow correction
- stage-discharge relation with constant fall backwater correction, and
- stage-discharge relation with normal fall backwater correction.
Depending on the envisaged computational procedure for the rating curve in some cases following parameter(s) should be added to stage and discharge:
- gradient or fall, if unsteady flow, respectively backwater correction is required
- cross-sectional parameters, if the rating curve has to be extrapolated beyond the measured range
With gradient the time rate of change of the water level during a measurement in m/day is meant, whereas fall is the water level difference in m between the base station and a second station in the backwater zone.
The stage-discharge data can be entered by:
- importing data from file, or
- via the screen.
Start the function by selecting from the Data Edit and Entry functions <Stage Discharge Data>. When you select a station from the <Station codes> list box hymoswill present in the dates list box all Stage-Discharge data found in the database for the selected station within the selected time period. From the dates list box you can select a date (with observation number) to edit. If you want to add a new record press <Add New>. After editing data press <Save> to save your changes to the database. If you want to save a record with a measurement date and observation number already existing in the database hymoswill ask you if you want to overwrite the existing record. If not Hymoswill not save your changes before you changed the measurement date or the observation number.
A current metering data-record comprises at least the following data:
- Date of the measurement : year, month, day
- Number of the observation : unique number in a day
- Zero level of the gauge : in m + M.S.L.
- Water level (h) : weighted average water level during the discharge measurement (m)
- Discharge (Q) : in m3 /s
- Width : width of the cross-section at the water surface (m)
The following data is not obligatory , but advised to fill in.
- Gradient (dh/dt) : in m/day (mind the sign! ) (if the unsteady flow correction is to be applied)
- Fall : in m (if you selected backwater correction)
- Wetted perimeter (P) : in m
- Cross-sectional area (A) : in m2
- Surface Slope (s) : m/m
- Hydraulic Radius : m (computed from R = A/P)
- Velocity (v) : m/sec (computed from v = Q/A)
- Manning's N : (computed from R, s and v)
- Mode of Crossing : 30 characters
- Method of velocity observation : 30 characters
- Number of verticals
- Maximum point velocity: m/sec
- Weather condition : 30 characters
- Wind velocity : km/hr
- Wind direction : Degrees
- Remarks : text
- Flag : yes/no included in rating curve calculation.
To import existing Stage-Discharge data from file, press <Import QH> and select the filename with your Stage-Discharge data.
The stage-discharge data file should have following layout:
Line 1
- Station code (format A10) and in column 11: G, F or N:
- if gradients are included
- if fall data are included
- if neither gradient not fall data are included
Line 2
- year, month, day of the measurement
- number of the measurement
- gauge zero (m + M.S.L.)
- water level (m)
- discharge (m3 /s)
- gradient (m/day) or fall (m) if G res. F is entered in line 1
- width (m)
- wetted perimeter (m)
- cross-sectional area (m2 )
- etc. for the next lines.
Note
- All data should be separated by comma's or blanks. To break off a record (if e.g. the last terms are not available) use /; the omitted values will then be set to the default = 0.
- The data should be in si-units.
Example
Stage-discharge data of station backwt including fall. The records are broken off after the fall. The water levels in this file as well as in the time series are given relative to gauge zero; hence no shift is required and the gauge zero can remain 0.0. The layout of the data file is shown below.
backwt f
1990 1 1 1 0.0 5.907 1160 1.917/
1990 1 3 2 0.0 7.105 1520 2.182/
1990 1 3 3 0.0 5.026 889 1.597/
1990 1 8 4 0.0 7.013 1490 2.225/
1990 1 10 5 0.0 11.558 2830 2.880/
1990 1 11 6 0.0 8.108 1640 1.920/
1990 1 17 7 0.0 8.638 1990 2.652/
1990 1 18 8 0.0 3.139 399 0.808/
etc.
