A unique study of two Utah cities shows how urban landscapes are really irrigated—and why watering less may actually make many lawns greener.
Hansen, Allen & Luce associate Kayson Shurtz, P.E., led a study with researchers at Brigham Young University that found significant efficiency opportunities in landscape irrigation.
The paper, Insights into Efficient Irrigation of Urban Landscapes, was published this week. The findings have direct implications for water management in Utah and throughout the West.
Using a combination of remote sensing with 4-band imagery and on-site measurements from water meters, Shurtz’s team analyzed irrigated area, water use, and landscape health across thousands of customer parcels in two secondary water systems in Utah County.
“Data quality and availability were key for us to be able to perform our analysis that produced several takeaways,” said Shurtz.
The data 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.
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 the other system.
“As drought conditions persist and growth continues in our state, difficult decisions will need to be made to protect our water supply,” said Shurtz. “The results of this study provide some important information that will be useful for decision makers going forward.”
Some of the analysis presented in the research originated in HAL’s evaluation of Utah’s water use data for the Division of Water Resources.