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Hydrologic Conditions of the 48 Contiguous States, Summer (July-September) from 1961 through 1995

Annual streamflow ratio is estimated for each catalog unit as a percentage of long-term mean summer streamflow computed from data extracted from ~ 5,000 USGS gages for the months of July through September for the years from 1951 to 1980. Hydrologic conditions for each summer from 1961 through 1995 are characterized with respect to the long-term summer mean from 1951-1980 as follows:

Dry summer 0-75 percent of long-term summer mean Normal summer 75-150 percent of long-term summer mean Wet summer > 150 percent of long-term summer mean

Normalized summer runoff is estimated as the ratio of summer streamflow to the watershed drainage area (as cfs/square mile) based on the long-term (1951-1980) average annual summer streamflow and drainage area for gage stations in a catalog unit.

figures

F-1 Ratio of streamflow to watershed area for July-September, 1951-1980

(as cfs/square mile).

F-2 Persistence of dry hydrologic conditions during

September for the period 1961-1965.

F-3 Persistence of dry hydrologic conditions during

September for the period 1966-1970.

F-4 Persistence of dry hydrologic conditions during

September for the period 1971-1975.

F-5 Persistence of dry hydrologic conditions during

September for the period 1976-1980.

F-6 Persistence of dry hydrologic conditions during

September for the period 1981-1985.

F-7 Persistence of dry hydrologic conditions during

September for the period 1986-1990.

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