Daily duration hydrographs when overlain by current daily mean streamflow, help to characterize current streamflow in relation to historical flows at a site with respect to time. Daily duration hydrographs portray non-exceedance percentile intervals for each day of the year using running 7-day, 14-day, and 28-day flow averages.

Duration hydrographs previously developed for South Carolina have been replaced by duration hydrographs produced by the National USGS WaterWatch Webserver Team. Click on the link below to access the duration hydrographs on the national USGS Web page. To select South Carolina sites from a map, type in sc or S.C.

http://water.usgs.gov/waterwatch/?m=sitedur&r=sc&w=dryw%2Cmap

There are a number of ways to generate duration hydrographs:

• To generate a graph for a particular site, enter the station number in the “Site number” box.
• To select sites from a map, either type in name of the river or the state abbreviation in the “Site Number” box and a map will appear below the duration hydrograph.

A few cautionary notes on using the duration hydrographs on the WaterWatch page:

• Currently, the map incorrectly includes daily duration hydrographs for discontinued stations (no current daily value trace).
• Duration hydrographs are no longer classified and separately listed as REGULATED or UNREGULATED.
• The period of record for five sites includes unregulated and regulated periods and erroneous duration hydrographs are produced. The five sites are:
  • 02129000 Pee Dee River near Rockingham, NC
  • 02146000 Catawba River near Rock Hill, SC
  • 02197000 Savannah River at Augusta, GA
  • 02197500 Savannah River at Burtons Ferry Bridge near Millhaven, GA
  • 02198500 Savannah River near Clyo, Ga.