Precipitation on the Beaver Creek Watershed

(Include histograms of avg. monthly ppt for 3 veg types)

Annual precipitation on the Beaver Creek watershed varies greatly from year-to-year, which is characteristic of the climate in the Southwest (Baker 1999b). On the average, the ponderosa pine forests receive 500 to 635 mm of water annually from rain and snowfall and the pinyon-juniper woodlands receive 460 to 500 mm per year.

Precipitation (inches) falling on the Beaver Creek watershed was measured with a network of about 60 gages throughout the period from 1957 through 1982. All hydrologic data were collected on a water year basis that ran from October 1 (Julian Day (JD 274) through September 30 (JD 273). Precipitation gage locations are designated in figure 2 by the symbol (R).

Monthly and annual precipitation totals (inches) for the years of record are included. We used three types of gages on Beaver Creek. Recording rain gages (0100 series), standard 20.3-cm (8-inch) rain gages located next to recording gages (0200 series), isolated standard 20.3-cm (8-inch) rain gages (0300 series), and Sacramento storage gages (0400 series).

Precipitation measured in the standard 20.3-cm (8-inch) rain gage was used to designate the true amount at each site. Recording gages were used to prorate the amounts measured in the standard cans. Sacramento storage gages were used in remote locations and read only twice a year.

All watersheds on Beaver Creek had 3-to-6 precipitation gages installed on them. Average watershed precipitation inputs were subsequently determined using the Theissen Method of averaging for the allotted number of precipitation gages.

Precipitation data include precipitation depth by gage, by watershed average, and precipitation chemistry. Data were collected from recording rain gages, digitized, and computerized along with total amounts collected in the various storage gages, typically weekly totals. The precipitation data were then processed by a series of programs that created files for prorated storm, daily, and watershed average amounts along with seasonal, monthly, and annual totals. The following is a brief description of the files that are available (see documentation for list of files).

• Raw input data - data from recording strip chart and storage gage amounts for water years (WY) 1957 through 1982.
• Prorate data - data are comprised of precipitation increments based on standard rain gage amounts that were adjusted by precipitation timing from the nearest recording rain gage. Files are available for WYs 1957 through 1981.
• Storm data - including storm time and date, duration, amount, type of precipitation (rain, snow, or mixed), and intensities for 5, 15, 30 minutes, and 1, 2, and 6 hours. Files are organized by WY 1957 through 1982.
• Daily precipitation - prorated daily amounts for each gage site using the standard rain gage as the true precipitation amount and prorated by the nearest recording rain gage. Files are organized by water years 1957 through 1982.
• Watershed average daily, monthly, seasonal, and annual totals determined by the Thiessen method for WYs 1957 through 1982.
• Point rainfall amounts for 8 frequencies (15 min to 24 hr) and durations of 2, 5, 10, 25, 50 and 100 years were derived from State maps of Arizona (NOAA).
• Precipitation nutrient data - water quality information including conductivity and amounts (ppm) of Ca, Mg, K, Na, NH4, NO3, PO4, and total P.