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<br />RIO GRANDE COMPACT COM!HSSION REPORT
<br />
<br />ACCURACY OF RECORDS
<br />
<br />The Rules and Regulations of the Commission state that the equipment, method, and frequency of
<br />measurement at each gaging station shall be sufficient to obtain records at least equal in accuracy
<br />to those classified as "good" by the U.S. Geological Survey. Within the physical limitations of
<br />stream gaging, the agencies obtaining the records at Compact gaging stations have complied with
<br />these regulations.
<br />
<br />The accuracy of discharge data depends primarily on (II the stability of the stage-discharge
<br />relation or, if the control is unstable, the frequency of discharge measurements, and (2) the
<br />accuracy of observations of stage, measurements of discharge, and interpretation of records.
<br />
<br />The station description states the degree of accuracy of the daily records. .Excellent~ means
<br />that about 95 percent of the daily discharges are considered to be within 5 percent of true value;
<br />"good~ within 10 percent; and "fair" within 15 percent. "Poor~ means that daily discharges have
<br />less than Rfair~ accuracy.
<br />
<br />The phrase .within 5% of true value" used to qualify "excellent" records establishes the
<br />extremes of the probable errors for 95% of the days in a given period of time. The word "within"
<br />defines the range of errors with individual daily values falling between 95% and 105% of true
<br />value. The probable error in a monthly or annual mean discharge depends more on the distribution of
<br />the daily errors between these tW'o limits than it does on the limits themselves. For this reason
<br />monthly and annual records are much more accurate than most daily records.
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