Water for a Sustainable World, Limited Supplies and Expanding Demand Second International Conference on Irrigation and Drainage Phoenix, Arizona May 12-15, 2003
Sponsored by U.S. Committee on Irrigation and Drainage
Edited by Albert J. Clemmens (Agricultural Research Service, USDA) Susan S. Anderson (U.S. Committee on Irrigation and Drainage)
Published by U.S. Committee on Irrigation and Drainage 1616 Seventeenth Street, Suite 483 Denver, CO 80202 Telephone: 303-628-5430 Fax: 303-628-5431 E-mail: email@example.com Internet: www.uscid.org
WATER CONSERVATION: SAVINGS DETERMINATION IN NEAR REAL-TIME
Bryan Thoreson, Penny Kosciusko, Joseph Burns, Grant Davids, Kirk Dimmitt, Jack Keller, Mike King
The Imperial Irrigation District (IID) and the Metropolitan Water District of Southern California (MWD) entered into a pioneering water transfer agreement in 1988. MWD was to finance water conservation programs in the IID in return for the transfer of the conserved water volume each year for 35 years. The agreement required that the water conserved be verified
This paper describes the information system module that determines water savings from a variety of system and on-farm conservation projects in near real- time. The system integrates data from Supervisory Control and Data Acquisition Systems (SCADA), data loggers, CIMIS, agricultural delivery data and volume pumped by tailwater return systems with distribution system configuration and project information.
Colorado River system operating conventions require that the volume of water conserved by IID and made available for transfer to MWD be projected prior to the start of each Calendar Year. In line with the Water Conservation Agreement, the Water Conservation Measurement Committee (WCMC) established the convention of using the verified water savings from the proceeding Water Year.
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(October through September) for the projected savings for the upcoming Calendar Year8. The verified savings are computed using data and algorithms stored in the Conservation Projections Module of the Water Information System (WIS) of the IID under the direction of the Conservation Verification Consultants (CVC) and the WCMC.
The IID and MWD agreed to a pioneering water transfer agreement in December 1988 (Agreement). MWD financed an IID water Conservation Program (Program) in return for the transfer of the conserved water volume each year for 35 years. Because the Agreement had the potential to impact other water users, the water conserved must be verified. Dimmitt (1998) provides details about Program organization and Projects implemented.
The WCMC engaged the CVC to verify water conserved and prepare water Conservatzon Projections. Conservation Projections are defined as the estimated Project Net Conservation Savings forecast for the upcoming calendar year. A set of precisely defined terms supporting verification of the conserved water is used throughout this document. These terms are in italics. Colorado River System conventions require that water available for transfer from lid to MWD must be projected prior to the start of the Calendar Year. Thus, each year, the CVC computes Conservation Projections based on the just completed water year. In December, the WCMC reviews and adopts Conservation Pro/ections for the upcoming year. After approval, a final report detailing the Conservation Projections is produced.
Over a period of years, the CVC developed conservation verification strategies (Burns, et. al., 2000) and algorithms for each Project. During that time, the need for an accessible historical database became apparent. This historical database came on line January 1, 1996 as liD’s Water Information System (WIS). Data is transferred to the WIS from IID’s SCADA and business computer systems and other sources for historical warehousing (Thoreson, et al., 1999). All data is quality controlled prior to use in the verification algorithms (Archer, et al.,”This paper describes the WIS Conservation Projections module that integrates: stored data and computes the Conservation Projections. The module outputs are: discussed; followed by discussion of required data, design concepts, and a summary.
According to this convention, the cumulative actual conserved volume lags the projected volume by one year, with the maximum difference be~’een the two ~ values limited to the difference between consecutive years. There is no cumulative error between the projected and actual conservation savings.
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TO VIEW Table 2, DOWNLOAD PDF:
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The data required from other modules can be classified as constant, infrequently changing and time-series data. Constant data relates the water delivery gate to structural aspects of the water delivery system. This data changes when construction alters the structural aspects of the water delivery system. Delivery gate attributes identi~ the spillage site and intercepted area each delivery gate is related to. These attributes must be specified when a new delivery gate is added. Infrequently changing data relates to water saving, on-farm water application and handling systems sponsored as part of the IID/MWD water Conservation Program. These systems may exist at other gates, but are included here only if they were sponsored by, or installed as a direct result, of the IID/MWD program.
The Conservation Projections Module presents the Conservation Projections in terms of Conservation and Consequential Effect Elements. Conservation Elements are reductions in water uses or losses due to the effects of a conservation Project. Consequential Effect Elements are increases in water uses or losses due to the effects of a conservation Project. Conservation and Consequential Effect Elements computational details are described in detail in Verification Summary Reports. Each project’s Net Conservation Savings is the difference between the totals of its Conservation Elements and its Consequential Effect Elements.
Conservation and Consequential Effect Elements are sub-divided into “sub-elements.” Sub-elements are annual values that cannot be further subdivided. Elements and sub-elements are classified as Fixed or Time-dependent elements. Fixed elements are Conservation or Consequential Effect Elements that do not change with respect to time or change sufficiently slowly that they can be held constant for periods of five years or more. Time-dependent elements are Conservation and Consequential Effect Elements that change over time and therefore must be recomputed for preparation of each conservation projection. The sub-elements often are flow measurements from specific locations. However, they can also represent classes developed for computing the reduction of a targeted flow path. Elements with sub-elements require detail pages as part of the
Conservation Projections report.
Five steps occur in the data processing to compute the Conservation Projections:
1. Programs process those elements requiring integration of data from more than one module placing the results in summary tables.
2. The current values of the Fixed elements are stored in a holding table.
3. The Time-dependent elements are collected and stored in a holding table.
4. The values in the holding table are used to compute each project’s Conservation Projection, which is initially stored in a holding table.
5. Following approval by the WCMC, the elements and Conservation Projections are moved from the holding tables to a table containing the time series &Historical Verified Savings (HVS).
Two types of processing are required before data from the WIS modules can be used to determine a Conservation or Consequential Effects Element. For elements based on deliveries to farms, the deliveries with conservation potential must be selected based on established criteria and summarized. Three independent programs conduct this processing. Elements requiring synthesis of the without project Spillage integrate delivery and spillage information in a “Spillage a Analysis.” Six programs integrate the delivery and Spillage data to compute the values required for three Conservation and one Consequential Effects Element. The Spillage Analysis relates Spillage in liD to the delivery flexibility provided to growers. This analysis provides an adjustment to historical Spillage for current levels of deliver?” flexibility and also estimates the incremental Spillage caused by program-sponsored delivery flexibility. The Spillage Analysis computes estimates of the spillage volume that would have occurred absent delivery flexibility.
The Spillage Analysis consists of a pre-spillage analysis/draft projections data review and the Spillage Analysis procedures. The pre-spillage/draft projections data review (Table 3) is a report that allows for a final quality control review and, if necessary, data corrections prior to the Spillage Analysis.
Fixed elements are not based on time series data. Although these elements are expected to change infrequently, their values could change due to changes in IID’s distribution system or operations. Therefore, provision has been made for these elements to change if necessary. The value of the Fixed elements is stored in a table in the CP Module. This table contains a history of the value of the Fixed elements if they have changed, but uses only the current value for the determination of Conservation Projections. Upon completion of pre-processing, a program collects all current fixed element values and places them in a holding table for use in either the draft projections or mid-year estimate report.
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Time-dependent elements, in contrast to Fixed elements, are based on time series data collected and stored on the WIS. Thus, the values of these elements change each year. Some of these elements use available WIS data that needs little or no additional processing. Others require processing of available WIS data to synthesis the without project condition (Bums, et. al 2000). After processing is complete, a program computes all Time-dependent element values. These values are placed in the same holding table as the Fixed elements for use in either the draft projections or mid-year estimate report.
Once the elements have been stored in the holding table, a procedure computes Project Conservation Projections. These values are stored in a holding table for use in the draft projections report or mid-year estimate report.
Historical Verified Savings
Following WCMC adoption of the draft projections, the Conservation Projections and all the elements for the upcoming year’s final projections are moved from the holding tables to the final time-series table containing the Historical Verified Savings (HVS).
Certain changes in the calculation of these values can be easily done, however, it was neither possible to plan for nor predict all changes. Changes in the sites required and the constants used in algorithms can be made with ease. However, changes in the algorithms themselves require changes in the processing and procedures within the CP module. Elements can be added or made inactive, however any processing required to compute the value of an added element will need to be developed. The value of Fixed elements can be modified by making the current element inactive and adding a new record for the element. Time-dependent elements vary according to the collected time-series data. Some of these elements use complicated algorithms to calculate the Conservation or Consequential Effect Element. Considerable effort was spent to design flexibility: into the application computing these algorithms and also to maintain a history. For simple elements, such as volume measurement totals, ifa site changes, the site is marked as inactive and the new site is added as an active record.
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An information system application has been developed that integrates near real-time quality-controlled flow, delivery and weather data tbr computation of Conservation Projections. A report detailing water conservation achieved by various projects over a 12-month period can be printed providing mid-year estimates of and draft and final Conservation Projections for the upcoming year. This report provides access to monthly mid-year estimates of what the next year’s Conservation Projections might be.
Key requirements in the design of the information system application were:
1. Conservation Projections and details available at the “push of a burton,”
2. Maintain a history of all inputs and computations,
3. Allow month-to-month tracking of projections,
4. Allow a draft projections report for review and, if necessary,, adjustments prior to finalizing the projections, and
5. All input data and final projections must pass rigorous quality control.
Archer, M.C.; A. J. Divine and B.P. Thoreson. 1999. Irrigation Flow Data Collection, Quality Control, Flow Computation and Site Monitoring. ICID 17th Congress, Granada,, Spain. Volume IA, pp. 289-299. Burns, J.14 G.G. Davids, A.K. Dimmitt and J. Keller. 2000. Verification-Based Planning for Modernizing Irrigation Systems. In Challenges Facing Irrigation and Drainage in the New Millennium. Proceedings from the USCID Water Management Seminar, Denver, CO. pp. 51-63. Dimmitt, A.K. 1999. Improved Irrigation Water Management~A Direct Benefit of a Water Conservation Program. In Contemporary Challenges for Irrigation and Drainage, Proceedings from the USCID Water Management Seminar, Denver, CO. pp. 55-65. Thoreson, B. P.; A. J. Divine and M. C. Archer. 1999. IID Water Information System – Irrigation Database Principles and Management. In Contemporary Challenges for Irrigation and Drainage, Proceedings from the USCID Water Management Seminar, Denver, CO. pp. 41-54.