Development of a Landscape Irrigation Runoff Mitigation System.

Urban/municipal water use continues to represent a significant portion of overall water demand across many regions of the U.S., and given the rapid pace of urban growth, the sector is likely see even greater increases throughout the coming decades.  Outdoor water use can account for 50% or more of annual residential water use, with studies showing that homeowners often overwater landscapes by as much as 2 to 3 times the amount needed. Water conservation has been a major focus of extension outreach programs, municipalities, and water management districts, yet adoption of these programs has been challenging, especially in relation to proper lawn/landscape irrigation practices. Irrigation runoff from lawns into adjacent streets and storm sewers is a persistent problem that has been compounded by day-of-the week irrigation restrictions in many communities.  A patent-pending ‘Landscape Irrigation Runoff Mitigation System’ (LIRMS) has been developed for mitigating irrigation runoff losses from residential, commercial, or recreational landscapes in situations where automatic irrigation systems are used; primarily where landscapes adjoin paved streets draining to storm water sewer systems. Low-cost, yet durable flow sensors have been designed for use in the system, capable of detecting very low flow volumes when runoff begins. If runoff is detected above a defined threshold, the flow sensor communicates back to the irrigation system controller, which is paused for a given period of time (pause time is depending on factors including soil texture/infiltration rate, soil moisture, slope, etc.) before resuming the irrigation cycle. Upon resuming the cycle, if runoff flow is again sensed, the system again is paused, with the cycle continuing until the run time has been satisfied or allowable irrigation window has expired. Results of 2015/2016 field tests on St. Augustinegrass lawn plots at the Texas A&M Urban Landscape Runoff Facility demonstrate that the system 1) reduces total runoff volumes by up to 50%, 2) reduces peak runoff flow rates by 10x (from 0.3 to 0.03 L s^-1), and results in improved soil wetting efficiency per liter of water applied.  The team is currently partnering with water purveyors in the region to determine how to best utilize LIRMS to impact municipal water conservation efforts.