Estimating low-flow frequency statistics for unregulated streams in Idaho

Abstract

Multiply By To obtain cubic foot per second (ft 3 /s) 0.02832 cubic meter per second foot (ft) 0.3048 meter inch (in.) 2.54 centimeter inch per year (in/yr) 25.4 millimeter per year mile (mi) 1.609 kilometer square mile 2.590 square kilometer Datums Vertical coordinate information is referenced to the North American Vertical Datum of 1988 (NAVD 88). Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83). Altitude, as used in this report, refers to distance above the vertical datum. Definitions Water year: In U.S. Geological Survey reports, a water year is the 12-month period from October 1 through September 30. The water year is designated by the calendar year in which it ends; thus, the water year ending September 30, 2001, is called the "2001 water year". Climatic year: In U.S. Geological Survey reports, a climatic year is the 12-month period from April 1 through March 31. The climatic year is designated by the calendar year in which it begins; thus, the climatic year beginning April 1, 2001, is called the"2001 climatic year."

Computing daily mean streamflow at ungaged locations in Iowa by using the Flow Anywhere and Flow Duration Curve Transfer statistical methods

“…The resulting estimated streamflow at the ungaged location should be verified to be hydrologically reasonable with respect to the streamflows at the streamgage. A general "rule of thumb" in other regression analyses is to use the traditional drainagearea ratio (equation 1) to estimate streamflow when the ratio of the drainage area of the ungaged location to that of the streamgage is between 0.5 and 1.5 (Hortness, 2006). Although the drainage-area ratio attempts to ensure continuity in streamflow as the distance between gages decreases, Archfield and Vogel (2010) noted that this rule of thumb generally appears to result in poorer agreement between observed and estimated streamflows.…”

“…The standard error values in logarithm (base 10) format represent the errors of equations developed by using the logarithm (base 10) transformed data. The range of percent error represents the errors for the final untransformed equations (Hortness, 2006). The standard error of prediction (SEP) also was computed for the ordinary-least-squares regression (table 4).…”

Usage des jaugeages volants en régionalisation des débits d’étiage

“…La régionalisation à base de relations empiriques simples entre débits de référence d'étiage et caractéristiques physiques et climatiques des bassins versants demeure une approche privilégiée par la communauté scientifique (HORTNESS, 2006;LACEY et GRAYSON, 1997;RIES et FRIESZ, 2000;TALLAKSEN et VAN LANEN, 2004). Le choix des variables explicatives se fonde sur les processus hydrologiques dominants, sur la facilité de calcul des variables et leur disponibilité dans les bases de données.…”

Estimating selected low-flow frequency statistics and harmonic-mean flows for ungaged, unregulated streams in Indiana

“…None of the QAH values were zero, so logistic-regression equations were not developed for QAH. Procedures and assumptions of logistic regression are described in detail elsewhere (Tasker, 1989;Ludwig and Tasker, 1993;SAS Institute, Inc., 1995;Allison, 1999;Hosmer and Lemeshow, 2000;Helsel and Hirsch, 2002;Hortness, 2006;Bent andSteeves, 2006, Eash andBarnes, 2012). Explanatory variables tested in the logistic regressions included numerous physical and climatic characteristics of each gaged basin (table 2).…”