Landscape and Irrigation is read by decision makers throughout the landscape and irrigation markets — including contractors, landscape architects, professional grounds managers, and irrigation and water mgmt companies and reaches the entire spetrum.
Issue link: http://read.dmtmag.com/i/282929
W e live in a time of chronically poor ground and surface water quality and uncertainty of sustainable supplies nation- wide. Cities face numerous water supply challenges, including: * Shortages of freshwater due to rising demand and shrinking cost-effective re- sources; and * Climatic oscillations that confound supply planning, such as more intense pre- cipitation and wasteful runoff, and less snowpack compounded by earlier melting, making storage more difficult for long-term management. Landscape management professionals — including landscape and general architects; engineers of all types; planners; municipal employees; and suppliers of water harvest- ing, piping and treatment equipment — should implement a sustainable water de- mand and supply-side portfolio. Such a portfolio must focus increasingly on local non-potable water resources — such as re- cycled water, greywater, rain and stormwater — for landscape irrigation. Additionally, such professionals should consider the at- tributes of precipitation harvested as rainwa- ter or stormwater for direct-active, or indirect-passive applications. This article fo- cuses on manufactured structures to harvest rain for beneficial landscape uses. Rain v. Rainwater v. Rainfall v. Stormwater "Rainwater" and "stormwater" can be defined differently depending upon the agency, trade group or code. These defini- tions can be in conflict and lead to confu- sion. Similarly, this article avoids the lengthy topic of collection surfaces, that is, whether a roof, road, parking lot or other imperme- able surface. Wherever it lands, it can be har- vested and used, followed by differing degrees of treatment as required to meet local water-quality standards. Engineers like to use "stormwater" to cover all precipita- tion from a storm event. Some define "rain- water" as rain landing on roofs. This article will use "rain" and "precipitation" inter- changeably to describe the resource. The key concept here is that rain can be harvested from any impermeable surface given an ap- proved design by the local jurisdiction. (Rainfall is a measurement of how much rain has fallen on a surface; it is not a water resource, per se.) Primary benefits of harvesting precipitation The primary benefits of harvesting pre- cipitation are non-potable and potable water supply augmentation and receiving water quality improvement: * Onsite rain harvesting retains the max- imum rainfall possible on an annual and sus- tainable basis. This strategy produces the least amount of stormwater runoff and pollution entering the public right-of-way, e.g. the municipal storm sewer system; * Onsite rain harvesting effectively de- livers a water supply to an end use at an ac- ceptable water quality and minimal energy cost; and * Onsite rain harvesting is the least pol- luted water resource and cheapest to treat compared to stormwater flowing in the public right-of-way and available to harvest. By keeping rainwater onsite, less pollution enters surface water bodies, where water- quality violations can occur. Secondary benefits of harvesting precipitation Keeping precipitation onsite through various harvesting strategies, whether in storage tanks (active) or through permeable surfaces (passive), eliminates stormwater runoff, and has these additional benefits: www.landscapeirrigation.com Irrigation and Water Management Rain Harvesting: Local landscape water supply 101 By Neal Shapiro, CPSWQ, CSM All photos provided by Neal Shapiro of the City of Santa Monica 22 Landscape and Irrigation April 2014 Left and top right: This 13,000-gallon cistern at 2602 Broadway in Santa Monica, Calif. was installed in early 2013. The city went with a cistern instead of an infiltration pit because of its goal of making the city self-sufficient on local water resources, eliminating the use of imported water. Using rainwater instead of imported water helps make the city more sustainable and self-sufficient. Bottom right: The finished landscape features sub-surface irrigation using rainwater.