Temporal analysis of the frequency and duration of low and high streamflow: years of record needed to characterize streamflow variability

• Published in: Journal of hydrology (Amsterdam) Vol. 310; no. 1; pp. 78 - 94
• Main Authors: Huh, Seungho, Dickey, David A., Meador, M.R., Ruhl, K.E.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.08.2005; Elsevier Science
• Subjects: Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Exact sciences and technology; Floods; hydrologic data; hydrologic models; Hydrology; Hydrology. Hydrogeology; Low flows; Natural hazards: prediction, damages, etc; statistical analysis; stream flow; Streamflow; temporal variation; Time series analysis; Trends; watershed hydrology; North Carolina; Virginia; South Carolina; United States; Trends; Floods; Time series analysis; Streamflow; Low flows; time series analysis; rivers; floods; least-squares; hydrodynamics; North America; frequency; drainage basins; drainage; cluster analysis; errors; low-water levels; standard deviation; streamflow
• ISSN: 0022-1694; 1879-2707
• DOI: 10.1016/j.jhydrol.2004.12.008

A temporal analysis of the number and duration of exceedences of high- and low-flow thresholds was conducted to determine the number of years required to detect a level shift using data from Virginia, North Carolina, and South Carolina. Two methods were used—ordinary least squares assuming a known error variance and generalized least squares without a known error variance. Using ordinary least squares, the mean number of years required to detect a one standard deviation level shift in measures of low-flow variability was 57.2 (28.6 on either side of the break), compared to 40.0 years for measures of high-flow variability. These means become 57.6 and 41.6 when generalized least squares is used. No significant relations between years and elevation or drainage area were detected ( P>0.05). Cluster analysis did not suggest geographic patterns in years related to physiography or major hydrologic regions. Referring to the number of observations required to detect a one standard deviation shift as ‘characterizing’ the variability, it appears that at least 20 years of record on either side of a shift may be necessary to adequately characterize high-flow variability. A longer streamflow record (about 30 years on either side) may be required to characterize low-flow variability.