California irrigation management information system

CALIFORNIA IRRIGATION MANAGEMENT
INFORMATION SYSTEM - (CIMIS)

Simon Eching

INTRODUCTION

California's 3.7 million-hectare irrigated agriculture and the 0.4 to 0.8 million-hectare landscape depend upon availability of reliable good quality water supply and efficient water management. The California Department of Water Resource (DWR), with other agencies, share the responsibility of providing information for efficient water use.
Through its various divisions, DWR examines water use and supply, develops plans to meet future water needs, and provides technical assistance, such as evapotranspiration information, required for irrigation scheduling. Evapotranspiration is the amount of water lost from the soil surface (evaporation) combined with the amount of water used by plants (transpiration). The combined values of these losses for irrigated grass is called reference evapotranspiration (ETo). Variations in ETo can be used as a guide to changes in crop or landscape water use. Using conversion factors and ETo, water use by a given crop or landscape can be estimated. The conversion factors are called crop coefficients and landscape coefficients. Since 1954, DWR has used evaporation pans to collect ETo data. In 1982, the California Irrigation Management Information System (CIMIS), a network of computerized weather stations, was established as an additional method to collect ETo data. CIMIS stations collect hourly solar radiation, wind speed, relative humidity and air temperature. All of this data is transmitted to a central computer in Sacramento where it is checked for accuracy. The CIMIS computer estimates reference evapotranspiration at station sites and stores it to provide on-demand-localized information.
This paper evaluates the success of CIMIS as a tool in irrigation water management. The increase in the number of users, information retrieval, indirect data acquisition, and effective methods of data dissemination are discussed. The expanding involvement of local agencies in the program is covered. In addition, the motivation to adopt CIMIS by irrigators, water savings achieved, and the benefit to the State is discussed.

BACKGROUND

CIMIS development began in 1982 as a research and development project between the University of California Cooperative Extension, and the Department of Water Resources' Water Conservation Office. Its goals were to:

Design a system which would use computerized weather data to estimate crop water use
Disseminate up-to-date quality information to the public
Provide irrigation scheduling programs to CIMIS users
Determined some crop coefficients

The equation chosen by the University to estimate reference evapotranspiration is a version of Penman's equation modified by Pruitt and Doorenbos (Proceeding of the International Round Table Conference on "Evapotranspiration", Budapest, Hungary, 1977). It employs a wind function developed at the University of California at Davis. The inputs used in the equation from CIMIS weather stations are these hourly values: solar radiation (from which net radiation is calculated), air temperature, wind speed, and vapor pressure.
The University of California completed the research and development phase of CIMIS in 1985 and accomplished the following:

Established a network of 43 automated computerized weather stations
Developed a CIMIS data dissemination system accessible through a phone line and computer
Determined some crop coefficients

Upon completion of this phase, the program was implemented by DWR.

PROGRESS

Since 1985, the number of stations, registered users, and calls to the CIMIS computer, have more than doubled. This progress is due in part to upgrades in equipment, the addition of dissemination points, and the outreach activities by the Department of Water Resource.
CIMIS is the largest standardized automated weather station network in the nation. The weather stations in the network have grown from 42 in 1985 to 98 at present. DWR owns 40 stations and the remaining 58 stations are owned and maintained by local agencies. DWR calibrates all stations annually.
The number of registered users (persons who have user ID's and passwords to access the system) has grown from 250 in 1986 to 2,900 in 1998. It is likely that the number of direct users is much higher because some people use other's IDs and password to access the CIMIS computer. Since the system is unable to detect when several people use one ID, the number of direct users is probably underestimated.

USER CATEGORIES

Although there are several categories of registered users, approximately 50 percent of the users are growers and consultants. The grower's category includes a range of operations, from large agricultural operations to specialty farmers who grow small, intensive truck crops. The consultants' category includes irrigation consultants and nonwater consultants. The nonwater consultants include those who do not deal directly with irrigation scheduling. Pesticide applicators, farm product suppliers, farm commodity buyers, engineers, weather forecasters, and environmental design firms fall under nonwater consultants. Public agencies, cemeteries, homeowners, park and golf course managers, city landscape managers, water agencies, and university make up most of the remaining 50 percent of users. There is some CIMIS use by nonagricultural groups including the Air Resource Board, wastewater engineers, landscape architects, reservoir designers, lawyers, and private investigators.

INFORMATION DISSEMINATION MEDIA

CIMIS data dissemination has expanded beyond direct access to the CIMIS computer. Various groups and organizations disseminate the information they obtain from the CIMIS computer. Table 1. lists six of these categories. The exact number of people who receive information from some of these sources is impossible to calculate due to their modes of dissemination. Consultants are those who have volunteered to have their names listed on the CIMIS computer. This list does not include all users in the consultants' category.

Table 1. CIMIS Dissemination Points.

*MEDIA*	*NUMBER*
Consultants	49
Newspapers	16
Telephone Recordings	19
Radio Stations	16
Computer Databases	3
WWW Sites and Links to CIMIS site	12

In the past 15 years, DWR, with other agencies, have developed materials on CIMIS, with farm advisors, State universities, the University of California, and other public and private agencies. DWR has ongoing irrigation workshops and experiments to determine crop coefficients. CIMIS Alert, has been developed to assist agencies setting up telephone recording systems. Additionally, CIMIS Agricultural Resource Book and CIMIS Urban Resource Book have been published. These books provide comprehensive information for the CIMIS program and include information on how public and private agencies are using CIMIS. They will reduce the research time for other agencies, which may want to prepare a water management plan or irrigation scheduling program. The multifaceted information dissemination approach adapted by CIMIS appears to be the most effective way of disseminating efficient water management and conservation information.

CIMIS INFORMATION RETRIEVAL

Direct calls to the central computer has averaged about 23,000 annually in the last three years. This number represents only direct calls by registered users. It does not include potential dissemination of CIMIS information by these users to others. The total number of hits to the ETo section of the CIMIS Web site is about 400 a week
The exact number of people who either receive or use information from some of these sources is not known. It is difficult to determine the number of people who use CIMIS information received through other computer databases, newspapers, public and private agency newsletters, and radio stations.
In a 1994 survey of 18 consultants to find out the extent that they used CIMIS in their services, it was found that 10 consultants used CIMIS data to provide services to 411 urban/agricultural customers. Irrigated hectare ranged from small landscapes of less than one hectare to 15,000-hectare farms.
The results of a survey of 17 agencies indicated that the monthly number of calls to their telephone recording systems ranged from 20 to 240. There was a high number of calls (18,000) to the National Weather Service (NWS). NWS recordings include other data, such as weather forecasts.
Five of the agencies had records of the number of calls to their systems. Based on these numbers, the average number of calls to the five telephone recording systems was 680 calls per month or 8,160 a year. The potential number of calls to all 19 telephone recordings is 31,000 calls per year.

BENEFITS FROM CIMIS

In 1995, the Department of Resource Economics at the University of California, Berkeley conducted a survey on the benefits from using CIMIS. The survey showed yield increases and applied water reductions from use of CIMIS. For the 54,000 hectares of irrigated land that the survey represented, there was an average annual yield increase of 8 percent. The survey results also found an average applied water reduction of 13 percent. For the 55 growers interviewed, reduction in applied water and the increase in yield amounted to an estimated annual benefit of $14.7 million. Table 2 shows the amount of money some of the 55 growers saved as a result of using CIMIS. Only a few crops were selected from each of the fruit and nut, vegetable, and field crop categories.
The 3,550 hectares of landscape in the survey had an annual applied water reduction of 2000 m3/hectare, or water cost savings of $2.3 million. For agricultural irrigators, water prices range from $0.015/m3 to $0.28/m3. For growers who face high water costs, the applied water reduction related benefits from CIMIS use are high.

Table 2:Water, Yield and Total Benefits to Growers from CIMIS

*Trees and Vines Sample*
Crop	Water † $	Yield ‡ $	Total $	Benefit/Hectare $
Almonds	246,000	2,426,500	2,672,500	408
Apples	900	13,900	14,800	366
Avocados	-141,350*	738,000	596,500	760
Grapes	00,850	1,336,500	1,437,3500	730
Pistachios	370,150	6,755,000	7,125,000	630
Plums	556	12,445	13,000	402
Vegetable Sample
Artichoke	2,500	326,200	328,700	160
Broccoli	2,750	106,100	108,850	730
Cauliflower	5,750	334,100	339,850	870
Celery	3,350	345,750	349,100	1700
Lettuce	26,000	1,361,000	1,387,000	920
Field Crop Sample
Alfalfa	47,790	325,700	373,500	100
Cotton	345,300	810,500	1,155,800	110

†Money saved due to reduced water bill resulting from using CIMIS.
‡IIncreased income from increased yield resulting from using CIMIS.
*Negative number indicates increased water use with CIMIS.

At the time of the UC study, local agencies and DWR had purchased 111 stations. Assuming a 15-year life, an interest rate of 7percent, and that the stations were all purchased in the same year, the annualized cost is $37,200. DWR operating budget for CIMIS is approximately $700,000 and the estimated operational costs to local agencies is $350,000 annually. The annual cost represented by the value of the land the stations occupy is conservatively estimated to be $8,325. The statewide cost of providing CIMIS, including the annualized capital costs, is approximately $ 1.1 million. The University of California Berkley estimated the statewide benefit from applied water reduction and yield increases of $32.4 million. Taking into account the $1.1 million expenditure, the net annualized benefits from CIMIS are approximately $31.3 million. The statewide Benefit/Cost ratio for CIMIS is 28 to 1.

SUMMARY

During the last fifteen years, CIMIS has undergone significant changes. The number of stations has more than doubled, cooperator stations make up most of this increase. The number of registered users has also increased at a rate of about 15 percent per year. No longer is CIMIS information disseminated by computer only, it has expanded to include the media, consultants, public and private agency newsletters, and telephone recording systems. While the number of information dissemination points have increased, the number of calls to the CIMIS computer has also increased. Benefits derived from use of CIMIS include crop yield and quality improvements, applied water reduction, and improved environmental quality management. This increases and benefits are interpreted as a testament of the effectiveness of CIMIS as a tool for improving water management and conservation.

REFERENCES

Eching, S.O, and D. Moellenberndt. 1997. Fifteen Years of Growth and a Promising Future the California Irrigation Management Information System. The Resource Agency, California Department of Water Resources.
Parker D., D. Zilberman, D. Cohen, and D. Osgood. 1996. The Economic Costs and Benefits Associated with the California Irrigation Management Information System (CIMIS): Final Report submitted to the California Department of Water Resources.