Optimizing Water Conservation

Abstract:

Fresh water is becoming a more limited resource and water management districts are looking for ways to conserve water. Agriculture, being a major consumer of fresh water in Florida, is a major in water conservation plans. This study attempts to maximize water savings for every dollar spent towards repairing irrigation systems that are not achieving best management practices. Previously completed farm audits and permit data were used to estimate the frequency of problems and their associated potential water savings occurring throughout the St. Johns Water Management District. These estimates, along with the cost to repair each issue, made it possible to create an optimizing tool to determine which repairs to make to yield the highest return on investment. The data showed the district can save 10MGD on the first $200,000 investment towards irrigation system repair. The marginal returns shrink as more money is invested with a maximum total savings of 40MGD if all issues are fixed costing between $10-25 million. These values are fairly significant because every four million gallons saved reduces agricultural daily consumption by 1%.

Introduction:

As Florida’s population continues to grow, it becomes more challenging to balance the demand for fresh water supply without negatively impacting the environment. In the St Johns River Water Management District, agriculture uses 413 million gallons per day (MGD) to irrigate 179,047 acres, which accounts for 35% of all fresh water consumption in the district. Permit data estimates two-thirds of the usages comes from the groundwater supply (SJRWMD 2011A). Getting farms to achieve best management practices on their irrigation systems is one way to reduce their total demand on the fresh water supply. Unfortunately, cost is always a limiting factor so I created a software tool using Microsoft Excel Solver™, which determines the most effective combination of issues to address to achieve the greatest water savings...