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 [Map: 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 and Pacific Islands New York Vermont New Hampshire Maine Massachusetts South Carolina North Carolina Rhode Island Virginia Connecticut New Jersey Maryland-Delaware-D.C.

Recession-Curve Displacement Method for Estimating Groundwater Recharge In Humid Regions

Determination of Recession Index (K)

The recession index (K) must be determined for each watershed before recharge can be estimated by the recession-curve displacement method with the RORA program. (Rutledge 1998) K is the time in days required for groundwater discharge to decline by one log cycle after the recession curve becomes nearly linear on a semilog hydrograph. K is determined from construction of a master recession curve representing streamflow during periods when most or all flow is contributed by groundwater discharge. The recession curve can be determined manually or with an automated procedure. A good discussion of the theory and methodology for determining K is provided by Rutledge (1998, p. 9).

 

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Page Last Modified: Tuesday, 17-Sep-2013 18:15:06 EDT