WSP11570

• File Number: 8111.807
• Description: Arkansas River Compact Administration - Stream Gage Evaluation
• Basin: Arkansas
• Date: 1/1/1980
• Author: USGS
• Title: Cost-Effective Stream Gaging Strategies for the Lower Colorado River
• Water Supply Pro - Doc Type: Publication

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SUMMARY

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The cost-effectiveness of the current operation of 19 stream gages

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oJ the hydrologic network that supports the Colorado River compact and

subsequent adjudications is found to be relatively close to the theoretical

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limits when the total uncertainty in annual-mean-discharge estimates is

considered. The current cost (1980) for the 19 stations is $110,900 and

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the sum of the uncertainties in the annual-mean-discharge estimates for each

of the stream gages results in an uncertainty of 113 ft3/s (cubic feet per

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second). The major portion of this uncertainty is contributed by the three

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stream gages that are on the mainstem of the Colorado River. Lesser, but

still significant, amounts of uncertainty are derived from the major diversions

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as minor return flow, determination of discharge results in less than 1 percent

of the total uncertainty.

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If a minimum of lZ visits per year to each stream gage is prescribed,

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the $110,900 budget can be adjusted among the gages so as to reduce the

total uncertainty to 94 ft3/s; with a 6-visit-per-year minimum, uncertainty

can be reduced to 87 ft3/s. In each of these cases funds are diverted from

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the minor-return-flow gages to the mainstem gages.

On the other hand, a level of uncertainty, llZ ft3/s, comparable with the

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current operations can be attained for $95,000 if the 6-visit minimum is

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maintained and for $101,000 with the lZ-visit minimum. Here again the shift

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of funds from the measurement of minor return flows to more measurements on

the mainstem is found to be the most cost effective.

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A significantly larger budget of $ZOO,OOO will reduce total uncertainty
in annual-mean-discharge estimates at the 19 stream gages to 48 ft3/s.

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