nawqa_precip is a line and polygon coverage of the precipitation values in
the Cook Inlet Basin National Water-Quality Assessment (NAWQA) study area
in southcentral Alaska. This coverage was created using a statewide map
showing lines of equal annual precipitation prepared for a flood frequency
study (Jones, S.H., and Fahl, C.B., 1994). Values for each polygon bounded
by lines of equal annual precipitation were generally determined by
averaging the precipitation values of the bounding lines.
The purpose of the coverage is to provide information on the amount of precipitation which occurs within the Cook Inlet watershed. This coverage, along with other GIS coverages, will be used to help locate water-quality sampling sites for the Cook Inlet NAWQA study.
Procedures_Used:
The coverage was created using a statewide map (1:2,500,000) showing lines of equal annual precipitation The map developed in 1993 as part of a flood frequency study of Alaska's streams and rivers. Values of precipitation for the various polygons were determined by interpolation between the isolines. Boundaries of this coverage were drainage-basin divides for areas draining into Cook Inlet using a coverage containing hydrologic unit codes (HUC).
Revisions:
None
Reviews_Applied_to_Data:
Coverage and documentation was reviewed by Roy Glass. Editorial review of documentation was done by Liska Snyder.
Related_Spatial_and_Tabular_Data_Sets:
None
Other_References_Cited:
Jones, S.H., and Fahl, C.B., 1994, Magnitude and frequency of floods in Alaska and conterminous basins of Canada: U.S. Geological Survey Water-Resources Investigations Report 93-4179, 122 p., 2 plates.
Notes:
None
None
As the precipitation map of Alaska is updated, updates to the coverage will be made. In 1998 there were no plans for updating the precipitation map.
None
Point_of_Contact USGS-WRD
Caution should be used when using scales smaller than 1:2,500,000
USGS EROS field office, Anchorage, AK, Roy Glass, Emily Binnian
Unknown
In addition to the standard items found in the polygon attribute table, one additional item, INCHES, was added to the table. INCHES represents the estimated annual precipitation, in inches, for the polygon.