Beaver Creek Watershed - Precipitation on the Beaver Creek
Watershed
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.