DRAINMOD – Calibration and Validation for Prediction of Drainage Coefficient and Water Table Depth

DRAINMOD model predicts the effects of drainage and associated water management practices on water table depths and drainage coefficients. It simulates the performance of a given system for a long period of weather record. The field evaluation of this model has been carried out by comparing model predicted drain flow and depth to water table with the observed data collected from water table management system installed at A-block of Eastern Farm, Agricultural Engineering College and Research Institute Kumulur during the year 2015-2016. The comparison between predicted and observed drainage coefficient and depth to water table with treatment of different drain spacing (7.5, 10, 12.5 and 15 m) and drain depth (75 and 60 cm) is made. The statistical measures indicated that, there was a close relationship between predicted and observed drainage coefficient during the calibration and validation period as indicated by average root mean square error value ranges from 12.3 to 15.7 and 19.63 to 26.19 and average Chi-squared test value ranges from 0.010 to 0.725 and 0.01 to 0.28. Similarly for water table depth, the average root mean square value ranges from 7.630 to 17.20 and 16.67 to 21.54 and average Chi-squared test value ranges from 1.19 to 2.365 and 3.90 to 5.02.