Everything you wanted to know about stage, but were afraid to ask ...

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Everything you wanted to know about stage, but
were afraid to ask ...

• Steve Robinson
• U.S. Geological Survey

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STAGE RECORD LOST DUE TO WEATHER EFFECTS ON GAGE
EQUIPMENT
1

• PRESSURE SENSORS
• PRESSURE LOSS
• PRESSURE GAIN
• ORIFICE MOVEMENT/LOSS

• STILLING WELLS
• FLOAT FROZEN
• WELL INTAKES FROZEN

ORIFICE
3
2
PRESSURE SENSOR

• PRESSURE LOSS
• USUALLY SHORT DURATION, though can encompass
  several days with a spike in between lows
• USALLY A RAPID DECREASE OR INCREASE
• USALLY AT NIGHT (COLDEST TEMPS)
• INTERMITTENT
• CAN HAPPEN DURING ANY COLD WEATHER MONTH

SPIKE
DECREASE
PRESSURE LEAK
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3
PRESSURE SENSOR

• PRESSURE INCREASE
• RESULT OF PRESSURE LINE BEING PINCHED
• RESULT OF PRESSURE LINE BEING FROZEN
• CAN HAPPEN ANYTIME, USUALLY LATER IN WINTER

INCREASE
ORIFICE LINE FROZEN/PINCHED BY ICE
5
4
PRESSURE SENSOR

• USUALLY HAPPENS DURING BREAK UP
• CAN HAPPEN SEVERAL TIMES ONCE ICE MOVING

TORN OUT
MOVED
ORIFICE LINE TORN OUT/MOVED BY ICE
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5
STILLING WELL

• CAN BE DIFFICULT TO DIAGNOSE
• OCCURS ANY TIME DURING WINTER
• FROZEN INTAKE WILL LOOK/ACT THE SAME

FROZEN FLOAT AND/OR FROSTED FLOAT TAPE
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5
STILLING WELL

• CAN BE DIFFICULT TO DIAGNOSE
• OCCURS ANY TIME DURING WINTER

FLOAT FROZEN/STUCK
8
6
STAGE RECORD AFFECTED DUE TO WEATHER EFFECTS

• FREEZEUP/BACKWATER FROM ICE
• FREEZEUP DROP IN STAGE DUE TO ICE FORMING IN
  CHANNEL (STORAGE), GENERALLY ONLY IN FALL, FIRST
  OR SECOND COLD SNAP
• BACKWATER FROM ICE, GRADUAL INCREASE IN STAGE DUE
  TO ICE BUILD UP, GREATLY AFFECTS STAGE-DISCHARGE
  RATING
• DIURNAL FLUCTUATION DUE TO FREEZE/THAW AND ANCHOR
  ICE
• CORRELATION WITH DAY/NIGHT
• CAN HAPPEN ANY TIME OF YEAR, USUALLY DURING EARLY
  OR LATE WINTER
• ICE OUT
• A GENERALSMOOTHING OF STAGE RECORD AFTER/DURING
  SPRING RISE
• SIPHON ACTION
• NOT VERY COMMON

9
7
FREEZEUP
BACKWATER FROM ICE
FREEZEUP AND BACKWATER FROM ICE
10
8/9
ICE JAM
ICE OUT
FREEZE AND THAW
DIURNAL FLUCTUATION (FREEZE/THAW)
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10
SIPHONING
SIPHON FLOW
FREE FLOW
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1
SIPHONING
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Confirm Streamflow During Ice Cover

• Ice affects open-water stage-discharge relations
• Stage-Discharge relation will not apply during
  ice-affected periods
• Streamflow must be verified by measurement
• Streamflow is estimated
• Available records
• Precipitation and temperature data
• Hydrographs of nearby stations

---Record affected by Ice---
Uinta River Below Powerplant Diversion, Near
Neola, UT