Storm-Water Bioinfiltration as No-Irrigation Landscaping Alternative in Semiarid Climates

Abstract

In semiarid cold desert climates, bioinfiltration gardens as green infrastructure storm-water management facilities show promise to serve as both on-site storm-water management and no-irrigation landscaping. Both services must be demonstrated for bioinfiltration to be considered green infrastructure, because most urban centers in cold desert climates in the western United States (e.g., Salt Lake City, Utah; Boise, Idaho; and Denver, Colorado) must import water from the Colorado River for landscape irrigation, radically changing local and regional hydrology. To verify that storm-water runoff can sustain properly selected plants, we installed soil moisture sensors in a bioinfiltration garden in a cold desert climate with a contributing impervious area to garden area ratio of 1∶1 and monitored soil water for one summer. In spite of the small contributing impervious area, we found that the minimum soil water potential (ψ) observed was −2.5 mPa. Plants native to cold desert climates often do not show signs of water stress until ψ drops below −5 mPa, indicating the selected plants did not experience water stress in this study. We conclude that with proper site design and plant selection, plants in bioinfiltration gardens can be sustained solely by runoff. If the bioinfiltration gardens are constructed in fall, winter, or spring, no irrigation will likely be needed for establishment.