Model for management of an on-demand irrigation network based on irrigation scheduling of crops to minimize energy use (Part I): Model Development

Abstract

A tool implemented in MATLAB®, called GREDRIP, has been developed to simulate the behavior of an on-demand irrigation network, taking into account crop distributions in an irrigable area. It was applied during two complete irrigation seasons (2015 and 2016) for weekly irrigation scheduling. This tool portends to be useful as a decision support system tool to manage on-demand collective irrigable areas with minimum energy costs at the pumping station and by performing an irrigation schedule to guarantee crop water requirements. Hence, it is possible to go from an on-demand irrigation management system to a restricted arranged operation, carried out with centralized management, where the manager of the irrigation network satisfies the demand of farmers within a short period of time. The main novelty of this paper is to show a simulation tool which integrate the energy efficiency of the pumping station taking into account irrigation events distribution according to the crop irrigation scheduling at each plot. In this regard, this tool respects the irrigation scheduling of farmers, and it controls the starting time for each hydrant to minimize the energy cost. It was applied considering two types of pressure regulations, i.e., fixed and variable pressure heads. The distribution of open hydrants and the starting times of the irrigation events at each case performed by this tool led to optimization of the flow discharge distribution in the irrigation network, guaranteeing adequate flow discharge and pressure to all hydrants, which affected the uniformity of irrigation in the plot. Although the regulation using fixed pressure management represented energy costs 10% higher than the regulation using the variable pressure head, this difference would not compensate for the implementation of variable pressure management given the complexity of managing a variable pressure head in a pumping station. The actual irrigation network management, which does not consider the energy efficiency at the pumping station, showed higher energy consumed and energy costs at the pumping system in comparison with the results using GREDRIP. This fact suggest that it is necessary to improve the technical advisory system for irrigation scheduling at the plot scale and irrigation network management.