Irrigation Water Storage Cost Reduced by Stream Level Control

Abstract

Irrigation water costs are becoming of greater concern as groundwater supplies decrease and irrigation demands increase. This paper compares water storage costs for a stream water level control system (SWLC), which provides underground storage, with storage costs for impoundments and excavated ponds. A Fabridam, an automatic, water-inflatable dam was used to control the stream water level for a distance of more than 3 000 m (9800 ft) upstream. Underground storage volume was calculated from data collected during the driest year (1983) of a four-year study. A least-squares regression line through measured water volume values was determined and extrapolated to the lowest expected stream elevation. From this relationship, it was estimated that a water volume of 900 000 m3 (730 acre-ft) could be pumped frm the creek for irrigation with the Fabridam in place. This storage volume was used to determine the size, number and cost of impoundments and excavated ponds required to provide equivalent storage. Annual costs of irrigation water storages are $0,039, $0,051, and $0,121 per m3 ($48, $63 and $149/acre-ft), respectively, for SWLC, impoundments and excavated ponds. The lower-cost SWLC method could be used on an estimated 5 million hectares (12.4 million ac) of land in the southeastern Coastal Plain.