In this study, the effects of various drainage systems on water and nitrate‐N losses were investigated using DRAINMOD‐N II. Required field data were obtained during three growing seasons of canola in a subsurface drainage pilot in Mazandaran Province, northern Iran. The calibrated model was used to assess the effects of different drain depths (D = 0.10–0.90 m with 0.10 m intervals) and spacing (L = 10–90 m with 10 m intervals) on seasonal drainage water and NO₃⁻‐N concentration in drainage effluents. DRAINMOD‐N II performance was assessed using different criteria including absolute deviation (AD), root mean square error (RMSE) and determination coefficient (R²). The simulated and observed drainage discharges (0.97 vs 0.96 mm day⁻¹) and NO₃‐N concentrations (9.1 vs 14.1 mg l⁻¹) were in good agreement in the calibration process. The model performance was also acceptable in the validation process (AD = 0.59–0.79 mm day⁻¹; RMSE = 1.01–1.28 mm day⁻¹; R² = 0.59–0.79 for drainage discharge and AD = 8.3–16.3 mg l⁻¹; RMSE = 12.4–27.6 mg l⁻¹; R² = 0.4 for NO₃‐N). Based on the scenario analyses, the D0.40L50 drainage system was the best one, resulting in fewer environmental effects from the nitrate‐N and water loss viewpoints. © 2020 John Wiley & Sons, Ltd.

中文翻译：

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用DRAINMOD-N II评估地下排水稻田的水和硝酸盐氮损失

在本研究中，使用DRAINMOD-N II研究了各种排水系统对水和硝态氮损失的影响。在伊朗北部Mazandaran省的地下排水试验中，在双低油菜籽的三个生长季节中获得了所需的现场数据。校准后的模型用于评估不同排水深度（D = 0.10–0.90 m，间隔0.10 m）和间距（L = 10–90 m，间隔10 m）对季节性排水和NO ₃ ^-- N浓度的影响在排水中。使用不同的标准评估DRAINMOD‐N II性能，包括绝对偏差（AD），均方根误差（RMSE）和测定系数（R ²）。在校准过程中，模拟和观察到的排水量（0.97 vs 0.96 mm day ^-1）和NO ₃ -N浓度（9.1 vs 14.1 mg l ^-1）非常吻合。模型性能在验证过程中也是可以接受的（AD = 0.59–0.79 mm day ^-1； RMSE = 1.01–1.28 mm day ^-1；排水排放R ² = 0.59–0.79，AD = 8.3–16.3 mg l ^-1 ; RMSE = 12.4-27.6毫克升^-1 ; - [R ² = 0.4 NO ₃‐N）。根据方案分析，D0.40L50排水系统是最佳的，从硝酸盐氮和水分流失的角度来看，对环境的影响较小。分级为4 +©2020 John Wiley＆Sons，Ltd.