Watershed Symposium 2018 has ended
Welcome to the official website of the 12th Annual Salt Lake County Watershed Symposium, November 14-15, 2018!  Free and open to all, the Symposium encourages a comprehensive review of the current state of our watershed while creating learning and networking opportunities for a broad array of stakeholders. Sessions cover a broad range of topics on water quality and watershed issues with local, regional, and national relevance. Hosted annually by Salt Lake County Watershed Planning & Restoration.

Powerpoints and audio recordings are available.  Click on a session and scroll down to the attached files.
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Thursday, November 15 • 10:05am - 10:35am
Water Use By Lawns and Other Landscapes of Salt Lake Valley

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Water Use By Lawns and Other Landscapes of Salt Lake Valley

We are measuring in situ evapotranspiration rates of well- watered lawns, and turfgrass alternative species in collaboration with Red Butte Garden and Research Park.

Full Abstract
As the population and urban water demand in the Salt Lake Valley continue to grow, outdoor water use is a growing target for conservation measures. Many property owners choose to ‘xeriscape’ their lawns, replacing turfgrass with a variety of plant species and mulch in order to reduce irrigation. While metering studies have demonstrated that turfgrass removal results in reduced water demand on average, turfgrass replacements can vary widely in their form, plant cover, and species present. There is a need for more accurate information about in situ water use (evapotranspiration, ET) rates in heterogeneous urban landscapes in order to predict water demand and adequately inform planning efforts. In collaboration with Red Butte Gardens, and the University of Utah Research Park, we are conducting a study on in situ ET of various species used in landscaping across Salt Lake City. We measured in situ ET rates on a well-watered Kentucky Bluegrass (Poa pratensis) lawn, as well as four turfgrass alternative species found in the ‘Water Conservation Garden’ at Red Butte Gardens. These species (Thymus lanuginosus, Veronica oltensis, Sedum spurium, and Bouteloua dactyloides) are also currently well-watered. In situ ET measurements involves briefly placing a portable clear PVC chamber (0.28 x 0.28 x 0.19m) over an individual plant, or patch of lawn and measuring changes in relative humidity within the chamber. We measured each species between 6 and 10 times between sunrise and sunset during 2-3 days in Summer and Fall, 2018, and used a loess smoothing and integration algorithm to calculate daily rates. Chamber measurements were calibrated based on previous measurements on urban lawns in California, although additional calibration is ongoing. Preliminary daily ET rates measured on August 3 and 6, 2018 were variable among Kentucky Bluegrass and turfgrass alternative species. Kentucky Bluegrass ET was 11.2 mm/d on average across five replicate sunny locations on this day, and 3.9 mm/d on average across 5 shaded sites. ET for the four turfgrass-alternative species, all in full sun, ranged from 4.1 to 9.8 mm/day. Several of the turfgrass alternative species do not fully cover the ground, so ET rates measured with the chamber method represent an under-estimate leaf-level transpiration and over-estimate landscape-scale ET. While additional measurements and comparisons with existing ET models, and scaling efforts are ongoing, our preliminary results suggest that species commonly used in ‘water wise’ landscaping are quite variable under well-watered conditions.


Rose Smith

Research Assistant Professor, University of Utah
Rose is a research professor at the U of Utah, interested in the intersections among urban infrastructure, hydrology, nutrient cycling.

Thursday November 15, 2018 10:05am - 10:35am MST
Lower Level - Ballroom C Utah Cultural Celebration Center, 1355 W 3100 S, West Valley City, UT 84119