Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 7/1/2001
Publication Date: N/A
Technical Abstract: As part of the S273 Southern Regional Project of the USDA-CSREES to provide more information on hydrologic and water quality models, this paper presents an overview and evaluation of the ARS Root Zone Water Quality Model (RZWQM). It discusses RZWQM characteristics including input/output, components and processes, user interface, and analysis options; distribution, training and target users; calibration; sensitivity analysis validations/assessments; limitations and applicability; and future developments. The RZWQM is a physically-based contaminant transport model that includes sub-models to simulate infiltration and runoff, water distribution, and chemical movement in the soil; macropore flow and chemical movement through macropores; ET; heat transport; plant growth; organic matter/N cycling; pesticide processes; chemical transfer to runoff; and the effect of various management practices on these processes. To assist the user RZWQM has incorporated databases, schemes to estimate soil hydraulic properties from minimum data, initialization wizards, an extensive help menu, a Windows 95 shell, batch mode, and an analysis option that allows output to be summarized by month or year. To successfully apply RZWQM, the input must be a combination of calibrated and measured values which usually includes calibrating in the order: water balance, organic matter pools, and plant growth. Most RZWQM assessments used one or two years of data to calibrate the model and then assessed the model using another year or two of data. Generally the RZWQM was found to adequately simulate ET, soil water content, percolation and runoff, plant growth, nitrate in soil and water, and pesticide fate. But some model assessments were unsuccessful in simulating nitrate and pesticide movement.