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RZWQM2 is an enhancement of the Root Zone Water Quality Model (RZWQM), created on users' requests. Main components of the model were extensively validated and improved, and several new components added. It emphasizes the effects of major agricultural management practices on physical, chemical and biological processes related to plant growth and development, the movement of water, nutrients, and pesticides, and surface energy balance. RZWQM2 is a one-dimensional model with a pseudo 2-dimensional drainage flow and water table fluctuation.

The model requires daily or hourly weather data (maximum and minimum daily temperature, solar radiation, wind speed, relative humidity, and rainfall), soil texture, soil bulk density, soil hydraulic properties (if known), and recorded management practices. It runs on a daily time step with exception of water and chemical movement that is on a sub-hourly time step.

RZWQM2 has all the following features:

1. State-of-the-science simulation of management effects on soil-plant systems;
2. Simulation of tile drainage systems and water table fluctuation;
3. Simulation of macropore/preferential flow in soils;
4. Options to use a generic plant growth model, quick plant modules, DSSAT CSM 4.0 models, and HERMES SUCROS model;
5. Simulation of surface energy balance from the SHAW model;
7. Sediment loss due to water erosion added from the GLEAMS model;
8. User friendly Windows Interface to facilitate input/output data management;
9. Built-in database for soil, plant, pesticides, and weather generator inputs;
10. Rule-based implementations of management practices;
11. On-line help, User Guide, and Publications on model parameterization and applications;
12. Automated Calibration and Non-Linear Uncertainty Analysis (PEST/BEOPEST);
13. Ability to obtain confidence intervals of simulation results due to uncertainty of model inputs (distributed inputs).

Operating System: Windows 7 and later.
Latest Version: 4.5; Release date: March 3, 2024

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