A unique study of two Utah cities shows how urban landscapes are really irrigated—and why watering less may actually make many lawns greener.
A BYU team recently published some creative research with significant implications for water sustainability.
BYU CCE alumnus Kayson Shurtz (now at Hansen, Allen & Luce, Inc.), undergraduate student Emily Dicataldo, and professors Rob Sowby and Gus Williams published the article, Insights into Efficient Irrigation of Urban Landscapes: Analysis Using Remote Sensing, Parcel Data, Water Use, and Tiered Rates, in the open-access journal Sustainability this week. The article is the first official product of the CCE Sustainability Lab.
Using a combination of remote sensing with 4-band imagery and on-site measurements from water meters, the team analyzed irrigated area, water use, and landscape health across thousands of customer parcels in two secondary water systems in Utah County.
“In urban areas, irrigation studies are usually limited to a few sites and not tied to customer parcels or plant health,” Sowby said. “An empirical study of multiple, full-scale water systems like this is very rare.”
The research showed that irrigation has an optimum point, and that watering more doesn’t necessarily make for greener grass. In fact, the most saturated landscapes were often just as unhealthy as the driest ones.
Further, more than half of customers in both areas were irrigating over the optimum amount. Cutting back wouldn’t just save water, it would actually improve landscape health.
“In a time and place where we’re looking for easy ways to save lots of water, that seems like an obvious choice,” said Dicataldo, a civil engineering senior.
Of the two water systems, one had tiered water rates and the other had flat water rates. Tiered rates are not always popular because of how they hit customers’ wallets, but the research proves that they do save water: Even though the tiered-rate system receives about 40% less precipitation than the other, its customers applied 22% less water and still had greener grass than those in the other system.
“Following last year’s drought, this research couldn’t be more timely,” Sowby said. “We hope our findings will inform water policy, planning, and management decisions, especially in Utah and throughout the West.”