Structured framework for converting open-channel irrigation networks into modern pressurised pipeline systems to improve water-use efficiency and optimise energy management

This research focuses on improving the efficiency, sustainability, and resilience of agricultural irrigation systems by transitioning from traditional open-channel canal networks to pressurised pipeline systems. Many irrigation schemes, particularly in regions such as South Africa, rely on canal-based distribution systems that experience significant water losses due to seepage, evaporation, and operational inefficiencies. In addition, these systems often lack the pressure control and flexibility required to support modern irrigation technologies such as drip and micro-irrigation, which depend on a reliable pressurised water supply. The study develops a structured framework to guide the conversion of canal systems into pressurised pipe networks. The framework integrates hydraulic modelling, energy analysis, economic evaluation, and multi-criteria decision analysis (MCDA) to evaluate different system configurations and identify feasible modernisation strategies. Using the Letaba irrigation scheme in Limpopo, South Africa, as a case study, several pipeline layout alternatives were generated and analysed. These alternatives are assessed under multiple design scenarios to determine appropriate pipe diameters, pressure conditions, and flow distribution within the network.

The study also evaluates pressure management strategies and explores opportunities for energy recovery through devices such as pressure-reducing valves and pump-as-turbine (PAT) systems, which can convert excess hydraulic pressure into usable energy. An economic assessment is incorporated to estimate capital costs, operational savings, and the overall financial feasibility of the proposed configurations. The alternatives are then compared using a multi-criteria decision analysis approach that considers technical, economic, and sustainability indicators. The outcome of the research is a replicable framework that can support engineers, irrigation authorities, and water management institutions in planning and evaluating irrigation modernisation projects. By integrating water conservation, energy efficiency, and improved operational performance, the framework contributes to more sustainable agricultural water management and supports broader water-energy-food nexus objectives in water-scarce regions.