Implications of Deficit/Surplus Irrigation for Targeting Water Conservation Programs

Authors:

  • Lisa R, Krentz, Jack C. Kiefer, PhD - Hazen and Sawyer
  • David Bracciano - Tampa Bay Water,

Landscape water use is generally estimated to account for more than 50 percent of single-family public supply in Florida. Although savings potential exists, certain conservation opportunities are constrained by the extent to which homeowner’s surplus or deficit irrigate. As such, this presentation explores the importance of targeted implementation of landscape water conservation programs to avoid outcomes contrary to what was originally intended.

Tampa Bay Water, a regional water supply wholesaler, provides water to six Member Governments serving a population of approximately 2.3 million people in the Tampa Bay region. As part its current Demand Management Plan update, a comprehensive parcel level evaluation of surplus / deficit irrigation was conducted for more than 440,000 single-family water customers across six water utilities in the Tampa Bay Region.

A critical component of quantifying opportunity for landscape savings is understanding actual landscape water use relative to theoretical plant needs. Using a relational geospatial database containing parcel attribute, account level billing and historical weather data, estimates of irrigable area, landscape water use and theoretical plant water requirements were derived. Various analyses were conducted to evaluate landscape water use, theoretical plant needs and water savings potential for three test groups:

• water use survey participants,
• irrigation meter customers
• all customers using indoor use assumptions

Both the water use survey and geospatial water consumption database provided indicators to refine assumptions regarding indoor use, identify potable irrigators from non-potable irrigators and to distinguish surplus irrigators from deficit irrigators. These results are being used to identify viable landscape water conservation programs and quantify the net benefits and cost-effectiveness of demand management alternatives.

This presentation will discuss the methodology and results of the surplus/deficit irrigation analyses. The implications for properly targeting landscape water conservation programs will also be discussed.

For more information, please contact the author at lkrentz@hazenandsawyer.com.

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