CRDSS_Task1_14-18_ReviewWeatherStations

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CRDSS TASK MEMORANDUM 1.14-18 Consumptive Use Model Review of U.S. Bureau of Reclamation Weather Stations and Recommended New Stations 1.0 ISSUE Climatic data from National Oceanic and Atmospheric Administration (NOAA) weather stations are used to determine agricultural crop consumptive use in the U.S. Bureau of Reclamation's (USBR?s) Colorado River System Consumptive Uses and Losses Report, 1981-1985 . It was recommended in the Phase I CRDSS Task Memorandum 1.14-1 that the weather station sites be checked for representativeness. This memorandum addresses that recommendation as it pertains to the Gunnison River basin. 2.0 DISCUSSION/ANALYSIS This review of NOAA weather stations encompasses only those stations used for the Gunnison River basin and as reported in the USBR's Colorado River System Consumptive Uses and Losses Report, 1981- 1985. The stations identified in the appendices of the report are listed in Table 1. Subsequent to the Colorado River System Consumptive Uses and Losses Report, 1981-1985, USBR personnel have proposed changes in weather station selection for some of the hydrologic units in Colorado. These recommended changes for the Gunnison River basin are summarized in Table 2. Within the Gunnison River basin, there are several NOAA weather stations that collect maximum and minimum temperature and precipitation data but were not used in the USBR's 1981-85 report or the proposed revisions. These stations are listed in Table 3. The listing includes only those stations with recorded data from 1975. Ideally, agricultural weather stations should be sited in level, open terrain representative of the local agricultural environment. However, most NOAA weather stations are located in urban areas; therefore, temperature measurements may not be representative. Precipitation measurements are influenced more by regional topography, thus an urban versus an agricultural siting should have very little impact. Site descriptions of the weather stations listed in Tables 1, 2, and 3 were provided by Nolan Doeskan, the Colorado State Climatologist. A review of the descriptions indicated that most of the sites are located in an urban environment. The sole exception is Cochetopa Creek, which is located on a ranch. Since the data collected by NOAA are the only data available, they are recommended for use in the Colorado River System Consumptive Uses and Losses Report . This review of representativeness only addresses the location of the selected weather stations for each sector relative to the location of the irrigated area. Recommended changes to the weather stations used in the USBR's report are based upon the following: Analysis of the maximum, minimum, and average temperatures and precipitation records for ? 1980 through 1990 1 A 275 01.09.95 1.14-18 Walter