Irrigation Water Supplied by Stream Water Level Control
ABSTRACT STREAM water levels in Mitchell Creek near Tarboro, North Carolina, were satisfactorily controlled for drought and flooding conditions by a water-inflatable dam (Fabridam). The reported 4-year period covers normal rainfall years in 1982 and 1985 (405 and 473 mm of rain for the corn-growing season and 80 and 82 mm of irrigation used, respectively); a dry year in 1983 (349 mm of rain and 175 mm of irrigation used); and a high rainfall year in 1984 (659 mm of rain during the corn-growing season and only 2 mm of irrigation used). By controlling the stream water level, runoff and drainage were redistributed, and adequate water was stored in the soil profile and shallow aquifer (2 to 7 m below the surface) to furnish irrigation water for eight center pivot systems, four volume gun hose reel systems, and one controlled-drainage/subirrigation system, irrigating 327 ha. Before the stream water level was controlled, only two center pivot systems and two volume guns, irrigating 79 ha, were able to operate and then only part time. Corn yields (4-year average) in fields with stream water level control were 27% more for nonsprinkler-irrigated fields and 71 % more in sprinkler-irrigated fields than in fields without stream water level control. These increased yields would pay for the Fabridam in 15 years, pay the cost of irrigation, and without tax break consideration give an annual return for management of $100/ha.