Irrigation efficiency in furrows partially closed at their ends

Abstract

Two furrow irrigation systems were compared, the first one consisting of applying constant flows through sifons for R (opportunity time to advance time ratio) values equal to 0.2, 0.7 and 1.2. The second system consisted of a semi-automatic reduction in the initial flow, through spiles, for R = 1.0. Both systems were tested for two types of furrow: open or traditional system (OS) and partially closed at the end (PCE), by using a triangle-form spillway made of iron foil type 16. It was observed that the recession time in PCE is relatively longer than in SA under both flow conditions and the recession time at the end of the furrow increased sharply as the R value increased under constant flow. For OS the recession time was shown to be a horizontal line. The average run-off flows in SA were much higher than in PCE, under both flow conditions. The run-off losses in PCE system, under constant flows, compared to OS system, were reduced in 72.22%, 79.23%, and 52.48%, for R values equal to 0.2, 0.7, and 1.2, respectively. Under semi-automatic reduction in the initial flow, these losses were reduced only in 25.07% for R = 1.0. The PCE irrigation system increased the irrigation efficiency by 29.40% in relation to the SA system under constant flow condition.