Abstract of Water-Resources Investigations Report 94-4020, Low-Flow Characteristics of Streams in Maryland and Delaware
By D. H. Carpenter, and D. C. Hayes
Hydrologic information on the variability of streamflow during low-flow periods is presented. At-site data on low-flow characteristics of streamflow under natural conditions are given for 94 continuous-record gaging stations in Maryland, Delaware, and surrounding States, and for 131 low-flow partial-record gaging stations in Maryland and Delaware. Equations and transfer methods are developed to estimate low-flow characteristics at ungaged stream sites in Maryland and Delaware for average 7-, 14-, and 30-consecutive-day low-flow discharges for recurrence intervals of 2, 10, and 20 years. Estimates of the accuracy of the methods are presented. Maryland and Delaware are divided into four regions on the basis of physiography and the results of regression analyses. Equations are developed from a generalized least-squares multiple regression technique to estimate low-flow characteristics for the Eastern Shore region, the eastern-Piedmont region, and the western region. Adjustments are necessary to low-flow discharges estimated from the equation for the western region because of the effects of carbonate rocks on low flows. An equation is developed on the basis of a distance-weighted average of low-flow discharges at gaging stations to estimate low-flow characteristics for the southern region. Two methods are developed for transferring low-flow characteristics to ungaged sites on gaged streams. One method transfers low-flow characteristics to an ungaged site either upstream or downstream from a gaging station and the other method transfers the characteristics to an ungaged site between gaging stations.
USGS Water-Resources Investigations Report 94-4020, 113 p. 6 fig, 12 tab, 10 plates, 37 ref.
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