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Title:   Author  item
                                            Ma, Liwangitem
                                            Ahuja, Lajpatitem
                                            NOLAN, B.T. - Us Geological Survey (USGS)item
                                            Malone, Robert

                                                         - *Rob*item
                                            Trout, Thomasitem
                                            QI, ZHIMING - Colorado State University
  Submitted to: Transactions of the ASABE
                                    Publication Type: Peer Reviewed Journal
                                    Publication Acceptance Date: 5/14/2012
                                    Publication  Date: 9/4/2012
                                    Citation: Ma, L., Ahuja, L.R., Nolan, B., Malone, R.W., Trout, T.J., Qi, Z. 2012. Root Zone Water Quality Model (RZWQM2): Model use, calibration, and validation. Transactions of the ASABE. 55(4):1425-1446.Interpretive Summary: The Root Zone Water Quality Model (RZWQM2) is a one dimensional model  simulating agricultural management effects on crop production and soil and water quality. This paper outlines the principles of calibrating the model component by component. Users should consult the RZWQM2 user manual distributed along with the model and a more detailed protocol on how to calibrate RZWQM2 in a book chapter. A case study illustrates the use of field versus laboratory measured soil hydraulic properties on simulated soil water, soil N, and crop production. It also demonstrates the interaction between soil and plant parameters in simulated plant responses to water stresses. The commonly used trial and error calibration method worked well for experienced users. However, the Parameter Estimation Software (PEST) optimization was more efficient than a grid search of model parameters. In addition, PEST provides sensitivity and uncertainty analyses that should help users in selecting the right parameters to calibrate.
                                Technical Abstract: The Root Zone Water Quality Model (RZWQM2) has been used widely for simulating agricultural management effects on crop production and soil and water quality. Although it is a one-dimensional model it has many desirable features for the modeling community. This paper outlines the principles of calibrating the model component by component. Users should consult the RZWQM2 user manual distributed along with the model and a more detailed protocol on how to calibrate RZWQM2 in a book chapter. A case study illustrates the use of field versus laboratory measured soil hydraulic properties on simulated soil water, soil N, and crop production. It also demonstrates the interaction between soil and plant parameters in simulated plant responses to water stresses. The commonly used trial and error calibration method worked well for experienced users. However, an automated calibration procedure was more objective. The Parameter Estimation Software (PEST) optimization was more efficient than a grid search of model parameters. In addition, PEST provides sensitivity and uncertainty analyses that should help users in selecting the right parameters to calibrate.


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