APPLICATION OF DRAINMOD UNDER SEMIARID CONDITIONS

The water table management model, DRAINMOD, was evaluated for possible applications under semi-arid climatic conditions by comparing the pre dicted midspan water table heights with the measured ones in four subs urface-drained test plots in Kota, India under the RAJAD (RAJasthan Ag ricultural Drainage) Research project. Though the measurements were al so made on the subsurface drain outflows, however, they could not be c onsidered in this study due to the submerged outlets during most part of this study. In general, a good agreement was found between the meas ured data and the predicted values. The average absolute deviations be tween the measured and predicted midspan water table heights ranged fr om 14 to 24 cm for the four test plots. The corresponding standard err ors of estimate ranged from 15 to 30 cm. The above range of values com pares favourably with the other validation studies that have been cond ucted to evaluate DRAINMOD and other mathematical models for the humid regions of North America. Based on our investigations, it appears tha t DRAINMOD can be used to design or evaluate subsurface drainage syste ms under the semi-arid climatic conditions. However, further evaluatio ns are warranted before any concrete conclusions could be drawn.