Tuesday, November 29, 2016

Focusing Irrigation Conservation Programs to Maximize Savings

By Mackenzie Boyer

Want to know how much potential a water utility customer has to conserve irrigation? First you need to know how much water they’re using. What about figuring this out for every customer in a utility? You’ll want to check out our recently published article “Mining for Water: Using Billing Data to Characterize Residential Irrigation Demand.” 

Treasure Trove
A utility’s monthly water billing records can hold a wealth of information - a gold mine, we would say. The monthly records, even when water meters measure only indoor and irrigation water combined, can provide a great insight into irrigation behavior of individual customers. And if the utility also has parcel identification data linked to their billing records? Jackpot. 

Research area

Tampa Bay Water just happened to have some very detailed, very comprehensive billing data for their six member governments (Pasco County, New Port Richey, Pinellas County, St. Petersburg, Hillsborough County, and Tampa). Our analysis of their data used over 30 million monthly billing records of over 165,000 customers - comprehensive, to say the least. The monthly total water use (indoor and outdoor combined) and parcel data were used to estimate each customer’s monthly irrigation demand (what we estimate customers actually used for irrigation). Each customer’s monthly gross irrigation required (GIR, what we estimate a landscape actually needed to be well-watered) was estimated using parcel, weather, and soil data.

Managing and manipulating the data required some heavy computing power. The statistical programs SAS and R were used, with R selected specifically to run a series of 875,000 calculations at UF’s High Capacity Computing Center. (It still took the computing center over a week to run all the equations.) ArcGIS was used to map customer locations and determine their site-specific weather and soil conditions. We grouped customers by their irrigation habits by comparing their demand to GIR (how much they irrigated compared to how much their landscape needed). Our groups were: high, medium, low and occasional irrigators.
Stay the Course
We found that many, many customers in the Tampa Bay region do not regularly irrigate (our occasional irrigator group). For this 85% of customers, the old adage “If it isn’t broken, don’t fix it” holds true. These customers should not be actively recruited for conservation programs because we don’t want to inadvertently increase their irrigation by recommending irrigation practices that use more water than their current practices.

Each occasional irrigator did not irrigate much, but the group was so large that the occasional irrigators were responsible for 51% of irrigation utility-wide. In contrast, only 2% of customers were classified as high users, and these customers were responsible for 9% of the irrigation demand.
Keys to Success
Successful irrigation conservation programs are far from one size fits all. Conservation programs should be targeted to the high user customers to maximize the water savings potential. Utilities often have the tools in their historical monthly billing records (even without the comprehensive data of Tampa Bay Water) to estimate how much irrigation customers use. Using this knowledge, they can direct conservation efforts to those who could benefit the most.

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