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Arid and semi-arid countries are facing the exhaustion of their fresh water resources and are being forced to use saline water (brackish groundwater and drainage water) for irrigated agriculture. The result is often disastrous, as extensive productive regions become salinized. Nevertheless, there is potential to expand irrigated agriculture through the increasing use of saline waters for irrigation.

This study presents an analysis of the performance of a transient state model for numerical simulation of water and solute transport, known as LEACHM-C. it is assessed for areas where saline water may be an option for crop production. The model estimates the salt and water balance of a soil profile given certain irrigation and crop rotation strategies.

The predictive capability of the model was successfully tested using one year of data from a field experiment in a dry region of India. Comparison between observed and predicted values of soil profile salinity (0-120 cm) was performed by graphical display techniques and by using four statistical indices: root mean square error (RMSE), coefficient of residual mass (CRM), coefficient of determination (CD) and modeling efficiency (EF). Based on the statistics, as well as the graphical displays, initial model simulations were marginal. The model over-estimated the measured values. The RMSE results ranged from 28 to 70%. Agreement was improved when water retention parameters a and b were adjusted using regression equations for calculating retentivity (Hutson and Wagenet, 1992). The RMSE values, following adjustment of the water retention parameters, ranged from 13 to 24%, indicating the importance of obtaining accurate values of soil parameters for optimum model performance.