Constant Hole‐Spacing Trail Tubes

Abstract

Low‐pressure irrigation systems are developed to reduce energy requirement and cost. A consequence of low pressure is a reduced sprinkler wetting coverage. Small wetting coverages cause high water application rates and surface runoff potential. Trail tubes are perforated polyethylene hoses designed to replace sprinklers and reduce surface runoff potential in low‐pressure irrigation conditions. Long tube length can be used to create large wetting coverage to reduce surface runoff potential. Previous design of trail tubes emphasized on variable hole‐spacing tubes. Such a design produced minimum tube length and material cost. Constant hole‐spacing tubes will be longer than variable hole‐spacing tubes but have manufacturing and installation advantages. In practice, such advantages can more than offset the additional material cost due to longer tubes. Therefore, the study of constant hole‐spacing design is needed to provide an alternative selection of trail tubes. In this paper, the hydraulics of constant hole‐spacing tubes are described. Laboratory measurements are conducted to evaluate theoretical results including tube elevation, tube discharge, and water pressure. A computer program is developed to facilitate the selection of hole spacings on trail tubes.