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DRAINMOD APPLICATION

DRAINMOD APPLICATION. ABE 527 Computer Models in Environmental and Natural Resources. Review. drainage design … soil water characteristic… hourly rainfall, daily max & min temperature relative yield input data set.

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DRAINMOD APPLICATION

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  1. DRAINMOD APPLICATION ABE 527 Computer Models in Environmental and Natural Resources

  2. Review drainage design… soil water characteristic… hourly rainfall,daily max & min temperature relativeyield input data set Note: A DRAINMOD hydrology simulation can be run without specifying a relative yield input data set.

  3. Objectives • After this lecture, you should get familiar with DRAINMOD application as for: • How to input your own data to DRAINMOD • required format; • What to consider for calibration purpose; and • How to use the model to predict subsurface • drain flow, water table depth, and crop yield. • for different drain spacings.

  4. W20 W5 W10 E20 E5 E10 Southeast Purdue Agriculture Center Drainage Field (SEPAC) Monitoring: Subsurface drain flow Water quality samples

  5. Model Inputs - Hourly rainfall - Daily maximum and minimum temperatures (measured on site or from nearby stations)

  6. Model Inputs - Hourly rainfall - Daily maximum and minimum temperatures

  7. Model Inputs - Drainage design parameters Note: parameter to be calibrated—Surface micro storage S1

  8. Model Inputscont. - Soil properties: soil water characteristic, saturated hydraulic conductivity Note: parameters to be calibrated— lateral Ksat; volumetric moisture at 0 cm tension;and the vertical hydraulic conductivity of the restrictive layer

  9. Model Inputscont. - Crop parameters Time distributions of effective rooting depths

  10. Calibration Procedure 1. Choose most uncertain parameters to be calibrated Range of parameter needed to be calibrated

  11. W20 W5 W10 E20 E5 E10 Calibration Procedure cont. 2. Choose plot and year to be calibrated --West block and east block need to be calibrated separately. --W20 and E20 in 1988-1989 were chosen.

  12. Range of parameter needed to be calibrated

  13. Calibration Objective Functions (1) Nash-Sutcliffe efficiency: (2)Absolute percent error: Aggregated function, combining (1) and (2):

  14. Automatic Calibration Parameter values against model Nash-Sutcliffe efficiencies

  15. Identify Optimum Parameter Set

  16. Representative observed and predicted drain flow graph

  17. Observed and predicted water table graph

  18. Predicted and observed relative yields

  19. SUMMARY • Nash-Sutcliffe efficiency (EF) for daily drain flow ranging from -0.66 to 0.81; • EF for water table depth from -0.66 to 0.9; • Statistical tests of EF indicating insignificant difference among the three drain spacings; • Both observed and predicted relative yields indicating yields decreasing with the increase of drain spacing; • Average percent errors ranging from 1.3 to 9.7% for corn yield and from -0.8 to 10.3% for soybean yield.

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