Optimization of Pumping Costs and Harvested Volume for a Stormwater Harvesting System

Abstract

A harvested stormwater and managed aquifer recharge system has been analyzed through both simulation sensitivity analysis and optimization to reduce operational pumping costs and increase the volume of water harvested. The simulation sensitivity analysis explored increasing the size of a storage tank, replacing the three harvesting pumps, and using wider tank trigger levels in the system operation. In the optimization, trigger levels and irrigation schedules were considered as decision variables. Various streamflow (input) series have been considered in the optimization by finding the optimal controls for each individual series or by finding the controls that best perform under a range of different conditions. Optimal controls for the current system were compared with those found for the system with new replacement pumps. The newly sized pumps were found to provide significant benefits by reducing pump operating costs by 5% and increasing the volume of water able to be harvested. Using wider tank trigger levels and altering the irrigation schedule so that the irrigation pump operated at a more efficient point also resulted in a small reduction in cost for the current system.