A DRAINMOD-based Decision Support System (DSS) for drainage and water quality in Illinois

Many hydrologic models have been developed to simulate agricultural systems over the years. However, the use of these models outside of the academic realm has been practically non-existent. Ordinary stakeholders who are directly impacted by various changes in management practices currently do not have a modeling tool to assist in their decision-making. This study seeks to encourage and enable model use by using a Decision Support System (DSS) for drainage and water quality in the state of Illinois. This DSS uses DRAINMOD (a popular field-scale subsurface drainage model) as its driving engine, but the modular nature of the DSS allows different models to be substituted as they are developed. The DSS generates necessary input files, provides considerable database resources, and supports drainage decision-making with several post-process models.; In order to validate the DSS, which uses broad databases and somewhat generic inputs, the DSS was tested using observed data from several sites in the Little Vermilion River Watershed. The performance of the DSS was also compared to model simulations using several calibrated input values and specific database resources. Results showed that the hydrology simulated using the calibrated inputs were more accurate than that of the DSS, however, the difference was not significant enough to exclude the DSS from practical use. When the nitrogen component was tested, the inputs of the DSS produced more accurate results than the calibrated nitrogen inputs.; The DRAINMOD-based Decision Support System for Drainage in Illinois was shown to be a useful tool for users of various skill levels. Increased soil database resources along with updating the DRAINMOD-N component were suggested to further increase the utility of the DSS.