| Popis: |
ENERGY requirements for pumping irrigation water were determined for subirrigation systems for three sites in eastern North Carolina. Subirrigation and sprinkler irrigation systems were designed for each site by using the simulation model, DRAINMOD, to insure that the designs would satisfy irrigation and drainage requirements under North Carolina's variable climatic conditions. The performance of each system was simulated using climatological data for a 27-yr period to determine the amount of irrigation water required on an annual basis. Seepage losses from subirrigation systems and sprinkler irrigation efficiencies were considered. Average annual energy requirements were determined for each irrigation method for both surface (stream or canal) and deep well water supplies. The results showed that subirrigation requires 4 to 8 cm/yr more water than sprinkler irrigation when seep-age losses and irrigation efficiences are considered. How-ever, subirrigation requires only about 9 and 6 percent of the energy required for sprinkler irrigation systems oper-ating at 340 and 690 kPa (50 and 100 psi), respectively. When a deep well water supply was assumed, subirriga-tion offered a 20 to 40 percent energy savings for two of the three sites and had about equal energy requirments with sprinkler irrigation for the third site. Simulations for Indiana and Florida locations with the same soil conditions resulted in similar trends for water and energy requirements. |
