# Presentation: 348426

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

- Steve Robinson
- U.S. Geological Survey

## STAGE RECORD LOST DUE TO WEATHER EFFECTS ON GAGE EQUIPMENT

- _PRESSURE SENSORS_
- PRESSURE LOSS
- PRESSURE GAIN
- ORIFICE MOVEMENT/LOSS

-    _STILLING WELLS_
- FLOAT FROZEN
- WELL INTAKES FROZEN

- ORIFICE

- 1

## PRESSURE SENSOR

- PRESSURE LEAK

**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**

- DECREASE

- “SPIKE”

- 2

## PRESSURE SENSOR

- ORIFICE LINE FROZEN/PINCHED BY ICE

**PRESSURE SENSOR**

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

- INCREASE

- 3

## PRESSURE SENSOR

- ORIFICE LINE TORN OUT/MOVED BY ICE

**PRESSURE SENSOR**

-  **USUALLY HAPPENS DURING “BREAK – UP”**
** ****CAN HAPPEN SEVERAL TIMES ONCE ICE MOVING**

- MOVED

- TORN OUT

- 4

## STILLING WELL

**STILLING WELL**

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

- 5

## STILLING WELL

- FLOAT FROZEN/STUCK

**STILLING WELL**

-  **CAN BE DIFFICULT TO DIAGNOSE**
** ****OCCURS ANY TIME DURING WINTER**

- 5

## 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 GENERAL”SMOOTHING” OF STAGE RECORD AFTER/DURING  SPRING RISE
SIPHON ACTION
NOT VERY COMMON

- 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 GENERAL”SMOOTHING” OF STAGE RECORD AFTER/DURING  SPRING RISE
- SIPHON ACTION
- NOT VERY COMMON

- STAGE RECORD AFFECTED DUE TO WEATHER EFFECTS

- 6

## FREEZEUP AND BACKWATER FROM ICE

- FREEZEUP

- BACKWATER FROM ICE

- 7

## DIURNAL FLUCTUATION   (FREEZE/THAW)

- ICE OUT

- FREEZE AND THAW

- ICE JAM

- 8/9

## SIPHONING

**SIPHONING**

- “FREE” FLOW

- SIPHON FLOW

- 10

## SIPHONING

- 1

## 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**

**Notes:**
This is  because ice cover usually affects open-water stage-discharge relations. Stream discharge must, therefore,  be verified by discharge measurements when streams are covered by ice. Discharge during ice-affected periods is generally estimated using available discharge measurements, temperature and precipitation records, and hydrographs from near-by streamgaging stations. The quality of ice-affected records relies heavily on having discharge measurements. 

The hydrograph shown here displays a discharge record affected by ice. Ice built-up on the control caused backwater at the gage. When recorded stages were applied to the stage-discharge relation erroneous estimates of discharge resulted. The three discharge measurements provide the only check on the true discharge for the two-month period represented by this hydrograph.