Water and solute transport in intermittent sand filtration was simulated with a modified HYDRUS 1D program. Field trials were performed through a 10 × 10 m infiltration basin located at Dissa agriculture area in the north of Gabes city (south-east Tunisia). Performance of the calibrated model has been statistically evaluated for its ability to predict water flow and solute transport. Comparisons between measured and simulated water content resulted in R2 and root mean square error (RMSE) average values of 0.88 and 0.74 cm3 cm−3 for the calibration period and of 0.86 and 0.78 cm3 cm−3 for the validation period, respectively. Predicted water quality parameters were found to be in best agreement with the measured results. On average, the model predicted COD and NH4-N concentrations well, with a RMSE of 1.06 and 1.26 mg L−1 respectively. However, it underestimated NO3-N concentration. Similar corresponding values were computed for the validation period indicating that the model is able to predict water flow and solute transport with a reasonable degree of accuracy.

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