Developing Streamflow Information from Miscellaneous Streamflow Measurements

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Developing Streamflow Information from
Miscellaneous Streamflow Measurements

• Presented by Ken Eng1 and Chris Curran2

1USGS, NRP, WRD, BRR-ER Reston, VA2USGS, WAWSC,
Tacoma, WA May 23, 2008
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Streamgage
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Miscellaneous Streamflow Measurement
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Methods to Estimate Streamflow Characteristics
with Miscellaneous Measurements

• Streamflow characteristics, Q7,10 , 7-day,
  10-year low flow.
• Methods for Miscellaneous Measurements
• Maintenance of variance extension (MOVE)
• Hirsch, 1982
• Base-flow correlation
• Stedinger and Thomas, 1985-ST85
• Q-Ratio Potter, 2001

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Methods to Estimate Streamflow Characteristics

• All methods rely on concurrent flows.
• Develop relationship among concurrent flows.
• Index gage continuous long-term streamgage.

Long-term gage
Misc. Site
2 concurrent flows
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Maintenance of Variance Extension (MOVE)
MOVE relationship is given by

• Transferring means and standard deviations.
• Means and standard deviations calculated from
  concurrent flows.

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Maintenance of Variance Extension (MOVE)
Example Estimate Q7,10 at 07048550 (West Fork
White River east of Fayetteville, AR) with a
single index site 07048600 (White River near
Fayetteville, AR).
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Maintenance of Variance Extension (MOVE)
Example Estimate Q7,10 at 07048550 (West Fork
White River east of Fayetteville, AR) with a
single index site 07048600 (White River near
Fayetteville, AR).
?
Q7,10(Index Site)0.8 cfs
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Maintenance of Variance Extension (MOVE)
Example Estimate Q7,10 at 07048550 (West Fork
White River east of Fayetteville, AR) with a
single index site 07048600 (White River near
Fayetteville, AR).
Q7,10(Misc Site) 0.54 cfs
Q7,10(Index Site)0.8 cfs
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Maintenance of Variance Extension (MOVE)
Example Estimate Q7,10 at 07048550 (West Fork
White River east of Fayetteville, AR) with a
single index site 07048600 (White River near
Fayetteville, AR).
Q7,10(Misc Site)0.37 cfs
Q7,10(Index Site)0.8 cfs
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Maintenance of Variance Extension (MOVE)
Example Estimate Q7,10 at 07048550 (West Fork
White River east of Fayetteville, AR) with a
single index site 07048600 (White River near
Fayetteville, AR).

• MOVE
• maintain
• equality
• between
• sample means
• and variances
• m
• s2 s2

OLS minimize
S (yi yi)2

Q7,10(Misc Site)0.37 cfs


Q7,10(Index Site)0.8 cfs
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Maintenance of Variance Extension (MOVE)

• Requirements
• 10 miscellaneous streamflow discharge
  measurements
• Spread out over several years.
• Independent base-flow segments/periods.
• Lowest base-flow periods (75 nonexceedances and
  above on flow duration curves-spread).
• At least one long-term (20 to 30 years)
  systematic streamflow record.

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Maintenance of Variance Extension (MOVE)

• Pros
• Easy
• Less biased than OLS.
• Well understood and documented.
• Cons
• Minimum of at least 10 miscellaneous streamflow
  discharge measurements.
• Uses log transformations no zero flows.
• Assumes a log-linear relationship.

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Base-Flow Correlation (ST-85)
The estimated flow characteristic is given by

• Transfers statistical moments, mp sp f
  (concurrent flow relationship).
• Stedinger and Thomas 1985 for details on
  computing mp sp .

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Base-Flow Correlation

• Requirements
• Minimum 10 miscellaneous streamflow discharge
  measurements.
• At least one long-term (20 to 30 years)
  systematic streamflow record.
• Only for estimating frequency based statistics,
  such as the Q7,10.

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Base-Flow Correlation

• Pros
• Less bias than MOVE.
• Studied extensively in peer reviewed literature.
• Cons
• 10 or more measurements.
• Log transformations no zero flows.
• More complex.
• Assumes the same distribution of extremes (i.e.
  droughts) at both sites.

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Q-Ratio
Q ratio is given by
where
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Q-Ratio
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Q-Ratio
(6 cfs)/(15 cfs)0.4
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Q-Ratio
Z0.375
(6 cfs)/(15 cfs)0.4
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Q-Ratio
Z0.375
Q7,10ms 0.375Q7,10is
(6 cfs)/(15 cfs)0.4
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Q-Ratio

• Requirements
• Minimum of 3-4 miscellaneous streamflow discharge
  measurements.
• At least one long-term (20 to 30 years)
  systematic streamflow record.

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Q-Ratio

• Pros
• Few miscellaneous streamflow discharge
  measurements.
• Less biased than MOVE and base-flow correlation.
• Simple.
• Cons
• Assumes base-flows are directly proportional.
• Assumes high degree of hydrologic similarity.
• Not ideal for 10 or more measurements.
• Not studied extensively in literature.

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Recommendations on Methods

• Less than 10 measurements-Q-Ratio.
• More than 10 measurements-MOVE.
• Single and paired base-flow strategy.
• Paired strategy t, base-flow recession
  constant.
• Index-site selection.
• Regional regression.
• Missed paired sampling useful in MOVE.

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References

• Hirsch, R.M. (1982), A comparison of four
  streamflow record extension techniques, Water
  Resour. Res., v. 18, no. 4., 10811088.
• Potter, K. W. (2001), A simple method for
  estimating baseflow at ungaged locations, J.
  Amer. Water Resour. Assoc., 37(1), 177-184.
  (http//www.awra.org/jawra/toc.html)
• Stedinger, J. R. and W. O. Thomas, Jr. (1985),
  Low-flow frequency estimation using base-flow
  measurements, U. S. Geol. Surv. Open-File Rep.,
  85-95, 25 pp. (http//pubs.er.usgs.gov/usgspubs/of
  r/ofr8595)