Do's and don'ts of irrigating slopes
1 May, 2006 By: Stephanie Ricca Landscape ManagementThese tips help you navigate the ups and downs of challenging terrain.
Slope irrigation presents challenges particular to the environment. Too much water and runoff drowns some areas while leaving others too dry. Too little water renders the whole system ineffective. Not sure if you've done the calculations right? Keep these tips handy:
DO remember the run to rise ratio: This measurement of the horizontal distance vs. the rise in elevation will help you measure dimensions on an irrigation plan and calculate the actual distance of the slope (not just how big it looks on your flat plan).
DO try to use low-angle or flat trajectory nozzles for zones at the top of the slope, advises Hunter Industries. These heads will reduce wind drift and have less throw radius, so they can be spaced closer together than a standard nozzle. If you use standard-trajectory nozzles at the top of the slope, tilt the heads down to the bottom of the slope.
DO choose a timer with several start times. Rain Bird advises using one with at least four per program. Then determine how long a station can be on before runoff starts. Divide the run time necessary to meet plant water requirements by this. Runoff will be reduced.
DO consider inline emitter tubing, or drip line, for low-volume irrigation, especially on steep, man-made embankments. Install the tubing horizontally to the slope on the surface. Drip irrigation is a good choice for conditions like this, especially when slopes consist of poor-quality fill dirt, according to DIG Irrigation Products, since it reduces runoff, and water loss by evaporation and windy conditions.
DON'T forget the check valve. These will eliminate water draining out of the lowest head after each irrigation.
DON'T use nozzles that have pressures that are too high or too low. You'll waste water and plants won't be at optimal health. Rain Bird advises using built-in pressure compensators to eliminate misting or wind drift common on a slope.
DON'T ruin the visual impact of a planted slope with riser-mounted sprinklers. Pop-ups cut down on vandalism and injury.
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