Hydraulic performance analysis of flexible gated pipe irrigation technique using GPIMOD model

Abstract

Background and Objectives: Gated pipe is a technique to develop and maximize the irrigation efficiency of surface irrigation. This study focused on hydraulic performance analysis of flexible gated pipe irrigation technique under operating pressure from 0.05-0.3 (bar) and using the GPIMOD model for predicting water distribution to evaluate the model's capability as a design tool to maximize irrigation efficiency. Materials and Methods: Two irrigation types were selected; the first was a traditional gated pipe, while the second was pressure compensating gated pipe. The field measurements were carried out at the private farm, Monufia Governorate, Egypt. Results: The results showed that a higher regulated observed and simulated discharge for pressure compensating gated pipe comparing with the traditional gated pipe under operating pressure 0.05-0.3 bar. This was due to the pressure compensating gated pipe was designed to adjust the pressure differences and improve discharge uniformity from each gate along the pipeline. The total outflow was increased by increasing pressure under traditional and pressure compensating gated pipe. Their slight variation between the total outflow for traditional and pressure compensating gated pipe. The total outflow under operating pressure from 0.05-0.3 bar were between 63.54-165.32 and 49.33-115.33 lit sec-1, respectively. The outlet discharge and total outflow coefficient "Cd" indicated that a good relationship between the measured and the simulated discharge through the gates along the pipeline. The results obtained of a uniformity coefficient %, coefficient of variation and standard deviation summarized, an acceptable percentage for the pressure compensating gated pipe comprising with traditional gated pipe for testing gated pipe irrigation. The results of GPIMOD model confirmed, there was an agreement good data between simulated and measured data. Conclusion: GIPMOD proved its high sensitivity to predict gate discharge and total outflow along the pipeline of gated pipe under different operating pressure.