Linear programming applied in the combined operation of the laterals and the ponds

Abstract

This study investigated the combined operation of the laterals and the ponds by applying the linear programming. The linear programming is able to give an optimal operation schedule so that the irrigation water requirement is reduced. As an important irrigation area with high density of ponds in Taiwan, the Chungli lateral and the neighborhood were thoroughly surveyed and the irrigation network was completed. Based on the water balance equations, the linear programming considered the spatial and temporal operation relation between the lateral, the ponds and the whole irrigation area. Due to limited water resources, the objective function of the linear programming is the minimum of the total requirement for the Chungli lateral. The combination in series or in parallel of ponds with the overflow either from one pond to the following fields or from one field to the other one was taken into account in order for an accurate numerical simulation. Besides from the ponds and the laterals, the supplementary water resources for irrigation include those from diversion weirs and effective rainfall. The ways to improve the present irrigation system for better utilization of water resources were also proposed. As an estimation, the pond dredging can reduce the water requirement by the amount of about 1 x 10rm3 for the original requirement 988.92 x 104m3 in the Chungli laterals.