Modeling of Subsurface Tile Drainage using MIKE SHE

Abstract

Abstract . Accurate estimation of subsurface drainage flow is essential for effectively evaluating the performance of management strategies in tile-drained landscapes. The objectives of this study were to calibrate and validate MIKE SHE for simulating subsurface tile drainage flow in central Iowa and to evaluate the simulated impact of two specific management strategies on tile flow. The model was calibrated and validated using the measured daily drainage in a 15.2 A— 38 m row-cropped plot during 2006-2009 with a split-sample method. Drainage time constant and macropore flow were found to be important in predicting drainage flow. The calibrated drainage time constant of 5.6 h was outside the recommended range, which might be attributed to the shorter response time of subsurface flow at the plot scale used in this study. The calibrated model showed a satisfactory performance in simulating daily tile drainage flow with Nash-Sutcliffe model coefficient values of 0.78 and 0.73 for the calibration and validation periods, respectively. The measured and predicted total drainage from 2006-2009 were 865 and 958 mm, respectively. The results suggest that MIKE SHE has potential for predicting tile drainage flows; guiding management decisions and for assessment of drainage design of water flow to downstream water bodies.