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Strategies to keep the water flowing
Of California's 10 million irrigated acres (4 million hectares), nearly 500,000 acres (200,000 ha), or 4.5% of the total, are under drip irrigation systems (1986). Two main types of drip irrigation systems are in use: above- and below-ground systems. Above-ground systems most often are used in horticultural crops and use 0.5inch to 0.75-inch (1.27-cm to 1.91cm) polyethylene tubing with emitters attached or in line at distances determined by plant spacing. Each emitter commonly delivers 0.5 to 2.0 gallons (1.9 to 7.6 liters) per hour.
Below-ground drip systems, used predominantly in annual crops, use 3- to 15-mil-thick (0.0076-cm to 0.0381-cm-thick), multi-chambered polyet hylene tubing called "drip tape." Water is discharged from small, laser-drilled orifices in the tube walls. Discharge rates range from 0.2 to 1 gallon (0.76 to 3.8 liters) per minute per 100 feet (30.5 meters) of tubing. A relatively new type of tape uses turbulent flow emitters that are welded onto the tape at specific intervals.
Clogging is the most serious problem facing operators of drip irrigation systems. It is common to both types of drip systems, although drip tape has smaller orifices and, therefore, has a greater potential for all types of clogging.
Clogging is caused by the presence of particles that reduce water flow. …