A Decision Support System for Evaluating the Effects of Alternative Farm Management Systems on Water Quality and Economics

Abstract

A prototype Multi-Objective Decision Support System (MODSS) for water quality has been developed by the Agricultural Research Service at the Southwest Watershed Research Center in Tucson, Arizona. The Decision Support System uses a simulation model to predict the impact of alternative management systems on surface and groundwater quality as well as farm income. The results of the simulation, which includes modeling of hydrology, erosion, nutrient and pesticide transport, crop growth and economics, are analyzed with respect to the multiple objectives of reducing surface and groundwater pollution while maintaining or improving farm income. Often these objectives are in conflict and objectively discerning which practice is preferred can be a difficult task. The multi-objective decision making component of the decision support system makes use of dimensionless utility functions and the concept of importance order dominance. The MODSS allows the user to set up alternatives, choose the decision criteria, and accept or customize the decision mode settings. The results are presented graphically as well as in tabular form. The dominance of one practice over another, if it exists, is clearly evident in the graphical presentation. We illustrate the decision component of the MODSS with pictures of the screens from an example which uses the simulation results of several management alternatives on farmland in the Deep Loess Soil Major Land Resource Area near Treynor, Iowa.