Optimizing Turn Assignments in Tree-Structured Irrigation Networks Using Computational Techniques

Abstract

The increasing scarcity of available water resources for agriculture has intensified the need for more advanced and effective methodologies for irrigation scheduling. While most of the simpler structural solutions have already been implemented, there is a growing demand for decision support systems that can manage the complexities of water resource allocation. This paper presents the development of WISCHE (Water Irrigation Scheduling), a comprehensive decision support system specifically designed to optimize irrigation scheduling in an arborescent network. The system has been successfully implemented in the "La Comunidad de Regantes, Riegos de Levante, Canal 2nd" irrigation area located in eastern Spain. This region covers 2188 hectares and consists of 2831 hydrants distributed across 20 sectors. Irrigation scheduling is required on a daily basis with five distinct time periods. The input data includes network topology, periodic demands, and historical consumption records, while the output is an optimized schedule of hydrant usage. The turn assignments generated by WISCHE must satisfy two types of constraints: the physical limitations of the irrigation network (including water flow and pressure) and the priority of demand based on previous consumption and requests. To address the physical constraints, the system employs a mixed 0–1 separable quadratic program. Furthermore, the system prioritizes hydrants based on their historical usage, with those previously underserved being given higher priority in future schedules. WISCHE has demonstrated success in balancing the needs of the network with equitable water distribution among users.