Evaluation and Comparison of Five Simulation Models for Estimating Water Drainage Fluxes under Corn
1998
Jabro, J. D. | Toth, J. D. | Fox, R. H.
The simulation accuracies of five water quality models, LEACHW, MACRO, NCSWAP, SLIM, and SOIL to predict the amount of drainage water were evaluated and compared to field data from a 5-yr leaching experiment. The study was conducted on Hagerstown silt loam soil (fine, mixed, mesic Typic Hapludalf). Drainage fluxes below the rooting zone of corn were measured with pan lysimeters in 1988–1989, 1989–1990, 1990–1991, 1991–1992, and 1992–1993. A series of 18 zero-tension pan lysimeters (0.465 m² area) were installed at a depth of 1.2 m to collect drainage water at approximately the rooting depth of corn. All five models were calibrated to the site conditions using data from 1989 to 1990. The calibrated inputs were then used to evaluate the models' simulating accuracy using 1988–1989, 1990–1991, 1991–1992, and 1992–1993 drainage data. The cumulative annual simulations of drainage water from each model were compared to the mean of pan efficiency corrected measured data for these five sampling years. Simulated results for all five models fell within 95% confidence intervals of the measured data. Validation simulations of drainage fluxes were about as accurate as calibration simulations. The statistical analyses indicated that all five models performed well and have the potential to accurately predict the amount of drainage fluxes below the 1.2 m depth under corn cropping system without the need to calibrate the model for each year. There were small differences among the overall performances of the models for simulating drainage losses, but these differences were not significant using one-way analysis of variance.
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