Groundwater Extraction with Minimum Cost. Application to Sprinkler Irrigation Systems for Corn Crop in Spain

Abstract

The aim of this study was to develop a DSS tool named DC-WAT, which linked with the already developed PRESUD tool, aims to optimize, in a holistic manner, the process of water extraction from an aquifer and its application in plot with a pressurized irrigation systems, obtaining the minimum total water application cost (CT) (operation (Cop) + investment (Ca)) per unit irrigated area improving water and energy management. This tool permits identifying the cost for transporting water from the source to the irrigation subunit inlet (Cws) and analyzing the irrigation system as a whole, from the water source to the emitter. An application to permanent sprinkler irrigation systems using groundwater of two types of aquifer (confined and unconfined aquifers) for corn crop in Spain is analyzed, evaluating the effects on CT of parameters such as the static water table in the aquifer (SWT), irrigated area (S), sprinklers and laterals spacing and average application rate (ARa). Results showed that Cws increased lineally with SWT and decreased exponentially with S. The timing of crops water requirements, the efficiency of the irrigation system, and the size of the irrigation subunit, among other factors, determine the optimal pumping flow rate and the cost of energy. For the aquifers studied, the Cws was mainly conditioned by the borehole investment cost, being the confined aquifer 30-60% more expensive than the unconfined for the studied cases. The Ce is the most important cost of CT (65-70 % in the studied cases). DC-WAT is a useful tool to optimize the design and sizing of water pumping facilities in irrigation systems, which considers the aquifer performance in a holistic manner.