An ecohydrological approach to conserving urban water through optimized landscape irrigation schedules

• Seasonal irrigation provides greater water savings at xeric landscapes than mesic.
• Daily irrigation at xeric landscapes uses less water than larger, infrequent events.
• At the mesic site, water use was minimized with larger, less frequent events.
• Xeric landscape could handle more stress with less risk to plant health than mesic.
• Municipal irrigation guidelines may greatly overestimate plant water requirements.

Despite the high percentage of residential water used outdoors, particularly in arid climates, there is a poor understanding of the fate of water used to maintain urban landscapes. Furthermore, opportunities exist for water conservation through improved irrigation schedules that take advantage of seasonal weather patterns and the natural ability of plants to resist water stress. This study uses a calibrated numerical model of soil moisture dynamics with meteorological data to determine irrigation schedules that minimize outdoor water use while maintaining specified levels of plant water stress. Results suggest annual irrigation well below local municipal recommendations, and substantial modifications to recommended schedules. Differences between xeric (low water use, drip irrigators, and gravel cover) and mesic (high water use, sprinklers, and turfgrass) landscaping, with respect to irrigation scheduling, soil water losses, plant water stress, and potential water savings, are presented to improve planning and maintenance of urban landscapes, particularly in water-scarce regions.