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Title: Long-term precipitation database, Walnut Gulch Experimental Watershed, Arizona, United States 1864

item Goodrich, David - Dave
item Keefer, Timothy
item Unkrich, Carl
item Nichols, Mary
item Stone, Jeffry
item Smith, John

Submitted to: Water Resources Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/26/2007
Publication Date: 5/6/2008
Citation: Goodrich, D.C., Keefer, T.O., Unkrich, C.L., Nichols, M.H., Osborn, H.B., Stone, J.J., Smith, J.R. 2008. Long-term precipitation database, Walnut Gulch Experimental Watershed, Arizona, United States. Water Resources Research, Vol. 44, W05S04, doi:10.1029/2006WR005782.

Interpretive Summary: The American Geophysical Union has a new thrust to make high-quality data available for research by publishing metadata for a data set that will be available on the web in an AGU-approved web site. This is one of a set of thirteen manuscripts describing data from fifty years of research and data collection at the USDA-ARS Walnut Gulch Experimental Watershed (WGEW) in southeast Arizona, USA. This work describes the long-term precipitation observations made at the WGEW, the network of raingages used to make these observations, and the associated data processing and quality control procedures employed. Several examples of the spatial and temporal characteristics of long-term precipitation observations are presented as well as a partial list of uses of these observations in a variety of research endeavors. All the data are available via the U.S. Department of Agriculture, Agricultural Research Service, Southwest Watershed Research Center (SWRC) at

Technical Abstract: An extensive precipitation database at the ~150 km2 Walnut Gulch Experimental Watershed (WGEW) has been developed over the past 53 years with the first records starting in August 1953 and continuing to the present. The WGEW is a tributary of the San Pedro River and is located in southeastern Arizona and surrounds the town of Tombstone. Average annual precipitation for the period of 1956-2005, as measured with six gages, is roughly 312 mm with approximately 60% falling during the summer monsoon. From a historical high of 95 raingages, a current network of 88 gages are operational. This constitutes one of the densest raingage networks in the world (~0.6 gages/km2) for watersheds greater than 10 km2. Through 1999, the network consisted of analog recording weighing raingages. In 2000, a newly designed digital gage with telemetry was placed adjacent (~1 m) to the analog gages. Both the analog and digital network of gages were in operation from 2000 to 2005 to enable a comparative analysis of the two systems. The analog data was digitized from paper charts and stored in breakpoint format. The digital data consists of rainfall depths at 1-minute intervals during periods of rainfall. All this data can be obtained in a variety of formats and accumulated over various time intervals (daily, monthly and annual) via a web interface at: