Efficient IrrigationThe plants we like to see in our landscapes grew and reproduced for millennium with precipitation as their only source of water. However in nature these plants are often found in conditions which cannot be duplicated in the urban landscape without supplemental irrigation. A water conserving landscape will not only include a selection of plants which demand little or no supplemental irrigation, it will also include irrigation systems which minimize water waste and take advantage of water sources other than treated potable water, like rainwater harvesting, air-conditioning condensate, and grey water. Efficient irrigation systems for large turf areas are dealt with a section 4.0 of this manual. For smaller turf areas, or mixed landscapes, subsurface, drip and micro irrigation systems can all assist in applying water in the root zone, and reducing water loss due to evaporation. Proper irrigation zoning can help to apply the correct amount of water to different plants with different water needs. Using alternative sources of water – rainwater harvesting, air conditioning condensate, or grey water can save the energy and chemical costs of treated water. In designing, installing and maintaining a water wise landscape, the use of automatic irrigation systems may occur where the need or preference of the customers is for plant materials which need supplemental irrigation. The use of handheld irrigation is often mandated during drought or water shortage restriction6, and should be considered as a recommendation for all water wise landscapes. The EPA reports that market studies have shown that, “Residences with automatic timers for irrigation, in-ground sprinklers, and drip irrigation systems use 47 percent, 35 percent, and 16 percent more water than residences without these systems respectively.”7 Water wise landscape in any case should always use the most efficient irrigation system possible for the circumstances found. Rain sensors, “Smart” water application technology, proper selection of equipment, zoning and use of alternate sources of water are all potential measures for efficient water use in landscape irrigation. In all cases a rain sensor should be used to prevent the use of irrigation water when mother natures is providing for the plants for free. Texas state law and regulation already requires that irrigation
systems be designed by licensed irrigators.8 However,
without local enforcement, there is no mechanism for ensuring compliance
with these regulations. Utilities that are concerned about water use by landscape
irrigation must provide for legal mechanisms ensuring that irrigation designs
and installations are performed by properly trained personnel. The Irrigation
Association has provided both a detailed Best management Practice9 and
training to irrigation professionals to help ensure that licensed irrigators
provide high quality services to their customers, and efficient irrigation
systems for the use of Texas precious water supply. With regard to landscape
irrigation, the utility’s role is to help develop policies and procedures
to support these efforts, and encourage compliance by customers either by
incentive or by rule. |
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6San Antonio City Ordinance Chapter 34-316, as amended, September
14, 2000. |
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