ETL 1110-2-537
31 Oct 97
Table 1
(ref: Table 4-5, EM 1110-2-1619) Equivalent Record Length Guidelines*
Analysis Setting
Equivalent Record Length
1. Long-period gauged record available at site
Use systematic record length
2. Long-period gauge on stream, drainage area within 20%
Use 90% to 100% of record length
3. Long-period gauge within watershed, model calibrated to gauge-
Use 50% to 90% of record length
based curve
Average years from regional study
5. Short-period event gauge in watershed, model calibrated to
Use 20 to 30 years record length
several events
6. Regional model parameter data available, no calibration
Use 10 to 30 years record length
7. Handbook/textbook model coefficients only
Use 10 to 15 years record length
*
Judgment should be applied to account for the quality of the data used in the analysis, degree of confidence in validated model, and
previous experience in similar studies in the area.
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