WDC18: Meteorological and Climate Data to Support ET-Based Irrigation Scheduling, Water Conservation, and Water Resources Management
(Multistate Research Coordinating Committee and Information Exchange Group)
Status: Inactive/Terminating
WDC18: Meteorological and Climate Data to Support ET-Based Irrigation Scheduling, Water Conservation, and Water Resources Management
Duration: 10/01/2010 to 09/30/2012
Administrative Advisor(s):
NIFA Reps:
Non-Technical Summary
Statement of Issues and Justification
Statement of Issue and Justification
Although the need for multistate coordination of irrigation water resources has always existed, recent droughts and a major population expansion in many western states has made this coordination even more imperative. Irrigated agricultural acreage is on the decline in many areas of the Western U.S., but it is still an important producer and the major user of water in most western states, where it is estimated that 90% of the freshwater drawn from well and surface sources is used for agriculture.
Irrigation scheduling models that have been developed to assist growers to estimate when and how much irrigation water to apply to their crops. Most, if not all, scheduling models use weather or climate data, which are commonly produced and disseminated by state or regional personnel. The data formats, however, vary by location, and local irrigation scheduling models only utilize local data. Data differences include time steps (hourly vs. daily), weather parameter order, and level of quality control. Clearly, there exists a need to coordinate weather data collection, storage formats, and data quality control in addition to sharing scheduling models.
Crop evapotranspiration (ETc) is commonly estimated by first calculating standardized reference evapotranspiration (ETref), which accounts for the weather influence on evaporative demand. Then, the ETref is multiplied by a crop coefficient (Kc) factor to estimate ETc. The ASCE-EWRI committee developed unique equations to estimate ETref for a short reference canopy (ETo) and for a tall reference canopy (ETr). Both equations are modifications of a version of the Penman-Monteith equation (ASCE-EWRI, 2005, Allen et al. 1998). Because new equations are used for ETref, questions have arisen about the accuracy of existing Kc factors. It is desirable to standardize Kc development and to find methods to make Kc values more universally applicable. During the period of the recent WERA-202 coordinating committee, a methodology to convert Kc values for use with ETo and ETr was developed. However, Kc values also vary with the cli-mate, irrigation system, and irrigation frequency, so further research/coordination is needed. There exist many varying methods used regionally and from state to state to address ET-based irrigation scheduling.
Irrigation scheduling models vary farm-to-farm, state-to-state, and region-to-region. There is need to coordinate, discuss, and review these models to improve and standardize methodologies and to provide clientele with the best possible information for irrigation management. One ex-ample of the need for better irrigation scheduling information and methods is the Environmental Quality Incentive Program (EQIP) program offered through the USDA Natural Resource Con-servation Service (NRCS). This program has begun providing cost-share money to producers to improve their irrigation water management. To be paid, the producers have to show documenta-tion of irrigation water management for the entire growing season. This has created a demand for irrigation water management training for producers and NRCS staff. These demands have further increased the need for accurate crop specific water use estimates.
Objectives
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Coordinate the documentation of crop coefficients used in irrigation scheduling including the following sub-objectives:a) Development of a database on available crop coefficient data in the U.S., and especially in the Western U.S.; including information on the method used to calculate ETref, the local climate, the time step used in the analysis, and the method used to determine the Kc curves (i.e., degree days, time, percent season, growth stage, etc.). This will involve assessment of the weather station design and siting, ETref calculation, data quality control, and ETc measurement. b) Work with ASCE Kc task subcommittee on the development of a procedure for standardizing crop coefficient data.Subcommittee members include: E. Martin, AZ; R. Snyder, CA; T. Marek, TX, S. Irmak, NE; M. Alam, KS; T. Peters, WA; J. Henggeler, MO; K. Bali, CA.
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Coordinate efforts to promote adoption of improved irrigation scheduling technology, including computer models based on crop coefficients and ETref, remote sensing and instrumentation that will help producers more efficiently apply irrigation water. Sub-objectives include the following:a) Evaluate effectiveness of technology transfer delivery methods and programs, and docu-ment application of ET-based irrigation scheduling by agricultural producers.b) Work with USDA-NRCS to provide and promote use of ET and irrigation scheduling in-formation to producers.Subcommittee members include: E. Martin, AZ; D. Porter, TX; T. Marek, TX; M. Alam; KS; T. Scherer, ND; T. Peters, WA; J. Henggeler, MO; S. Irmak, NE; K. Bali, CA.
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Coordinate the development of quality control (QC) procedures for weather data used for irrigation scheduling.a) Cooperate with WERA-102 on developing standards for QC data in all climate networks. Publish existing QC for all climate networks in each participating state in a document available to all potential users. b) Coordinate the development of estimation and interpolation programs to fill in missing data from climate networks, as irrigation scheduling programs typically do not run with missing data. Coordinate with weather station system suppliers on the need for high quality, reliable equipment and to assist them in supplying their customers with appropriate training and in-structional materials.Subcommittee members include: D. Porter, TX; E. Martin, AZ; T. Marek, TX; P. Palmer; T. Scherer, ND; B. Neff, Campbell Sci.; J. Henggeler, MO; K. Bali, CA.
Procedures and Activities
In this project, information sharing will occur mainly through the coordinating committee web-page. Any suggested changes to the coordinating committee webpage must be approved by both the Chair and Secretary, and the actual changes can only be made by the committee officers.
Objective 1: Coordinate the documentation of crop coefficients used in irrigation scheduling:
A subcommittee will search the literature and weather data network database to collect informa-tion needed to address Objective 1. As the Kc database is developed, the webpage will be up-dated with new information. The entire coordinating committee will coordinate with the ASCE-EWRI Kc Task committee in accomplishing task (b) in objective 1.
Objective 2: Coordinate efforts to promote adoption of improved irrigation scheduling technol-ogy, including computer models based on crop coefficients and ETref, remote sensing and in-strumentation that will help producers more efficiently apply irrigation water.
A subcommittee will address Objective 2 by searching for new and proven methods to encourage adoption of new technologies. The subcommittee can provide new methodologies and make re-ports on the coordinating committee webpage for sharing with other members. The subcommit-tee will also provide reports on accomplishments at annual meetings of the coordinating commit-tee.
Objective 3: Coordinate the development of quality control (QC) procedures for weather data used for irrigation scheduling.
Quality control procedures are needed to insure accurate data for computing reference evapo-transpiration and hence for efficient irrigation management. A subcommittee will conduct a lite-rature search and will contact managers of weather data systems to learn how people conduct QC. Based on the literature and compiled information, the subcommittee will prepare informa-tion on recommended QC practices.
Expected Outcomes and Impacts
- The outcome of will be the development and publication of methods for determining crop coefficients. Information on Kc data will be made available through the committee website. The impacts of this standardization will be an increased ability to share information on crop water use across state and regional lines, resulting in increased water conservation.
- The primary outcome will be an increased adoption of ET-based irrigation scheduling and other efficient irrigation technology. Target audiences will become more aware of and familiar with the technology and crop water needs. Water use efficiency will be increased, and limited irrigation water supplies will be better managed. These will be documented through evaluation surveys of program target audiences.
- This objective will result in the development and publication of quality control procedures that can be used to evaluate and improve weather data used for irrigation scheduling. The impact will be a more reliable weather data set that will result in improved irrigation scheduling and potentially an increase in yield per unit of irrigation water applied.
Projected Participation
View Appendix E: ParticipationEducational Plan
Many of the participants serve on committees of ASABE, ASCE, Crop Consultants of America (CCA), and the Irrigation Association (IA). It is not possible for everyone to attend and keep abreast of all the activities being conducted by these organizations. One of the major ac-tivities of this committee will be to have a session at each meeting that conveys to the group the activities in these other organizations and coordinates the activities among these groups. Another purpose of this committee is the on-going education of its participants regarding the activities on the web connected with irrigation scheduling. Specifically, the new committee will conduct the following activities:
1. Educational sessions at meetings about different aspects of irrigation scheduling material and software
2. Development of effective documentation of irrigation scheduling information available through the web.
3. Dissemination of information through newsletters, faxes, press releases and magazine articles, etc.
4. Development of short course information on irrigation scheduling using climate data.
Organization/Governance
The coordinating committee will have a Chair who is responsible for calling the annual meeting, preparing the agenda, Chairing the annual meeting, and obtaining approval of the previous meet-ing minutes. The Chair will form subcommittees to address the various objectives and tasks. The Secretary is responsible for writing the minutes and disseminating them for committee approval. In the annual meeting, the coordinating committee will elect a Chair and a Secretary for the fol-lowing year. The term of the new Chair and Secretary begins within two months after the annual meeting when the previous Chair provides the annual meeting minutes to the new Chair.