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Picture of dry creekbed of the Pedernales River, Texas.

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USGS IN YOUR STATE

USGS Water Science Centers are located in each state.

There is a USGS Water Science Center office in each State. Washington Oregon California Idaho Nevada Montana Wyoming Utah Colorado Arizona New Mexico North Dakota South Dakota Nebraska Kansas Oklahoma Texas Minnesota Iowa Missouri Arkansas Louisiana Wisconsin Illinois Mississippi Michigan Indiana Ohio Kentucky Tennessee Alabama Pennsylvania West Virginia Georgia Florida Caribbean Alaska Hawaii New York Vermont New Hampshire Maine Massachusetts South Carolina North Carolina Rhode Island Virginia Connecticut New Jersey Maryland-Delaware-D.C.

Duration Graphs

Duration graphs characterize the state of the hydrology of a stream with respect to time. To quantify the state of the hydrology for the current year, the current daily mean flows or running 7-day averages of flows are compared to selected non-exceedance percentiles computed for each day of the year over the history of the gaging station. In addition, the 7-day minimum flows with recurrence intervals of 10 years (7Q10) are shown on the graphs.

Explanation of Duration Graphs

Mean Daily Flow for Unregulated Streams

Mean Daily Flow for Regulated Streams

7-Day Running Average Flows for Regulated Streams
(Best suited for determining low-flow frequency of regulated streams)

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URL: http://al.water.usgs.gov/duration.plots/duration.html
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Page Last Modified: Monday, 14-Jan-2013 16:53:52 EST