Weather and Soil Moisture Based Landscape Irrigation Scheduling Devices: Technical Review Report - 2nd Edition

摘要

Water agencies implementing water use efficiency programs have long struggled to achieve quantifiable and reliable water savings. Historically, programs targeting landscape savings have focused on education pertaining to irrigation system maintenance,irrigation scheduling and climate appropriate plantings. Although these efforts have garnered savings, much potential exists for further landscape irrigation efficiency improvements. In the late 1990's, the Irvine Ranch Water District, Municipal Water District of Orange County and Metropolitan Water District of Southern California learned of an emerging irrigation management technology using weather based irrigation scheduling devices. This technology removes the need to make manual scheduling adjustments because the "smart" device adjusts the schedule automatically as weather changes. A water savings evaluation of this technology was implemented which is known as the "Residential Weather-Based Irrigation Scheduling -^sThe Irvine ET Controller Study".This evaluation identified an average single-family home savings rate of 37 gallons per day (irwd.com, 2001). In an effort to address non-point source pollution, a second weather based irrigation scheduling study was performed to evaluate the linkage between improved residential irrigation management and reduced dry-weather runoff. The "Residential Runoff Reduction (R3) Study" reported comparable water savings of 42 gallons per day per single-family home (irwd.com, 2004). Savings at non-residential sites were 545 gallons per day. The R3 Study also quantified a reduction in runoff ranging from 64 to 71 percent. With this change in runoff volume, concentrations of pollutants did not change therefore pollutants were reduced by a like amount. Although soilmoisture sensors have been used in agricultural and research applications for many years, this technology has only recently been applied successfully in the landscape irrigation field. Initial attempts to use soil moisture sensors to control landscape irrigation were unsuccessful due to the state of the technology, maintenance requirements and cost. Within the past several years, soil moisture sensor technology has advanced significantly with accurate and maintenance free systems being offered by several companies at competitive prices. Recent study findings indicate water savings resulting from soil moisture based smart systems are similar to those discussed above for weather based systems (Allen, 1997; Cardenas-Lailhacar et al., 2005; DeOreo et al.;Mecham).