Drainkim : water management model for assessment of the Re-use of drainage water

Abstract EN

Investigation of the origin of chemical composition of drainage water, accurate estimation of leaching requirement, and simulation of crop yield response are essentials for effective re-utilization of drainage water for irrigation and salinity control.

The comprehensive chemical model SAO (for the chemical evolution of drainage waters and soil solutions) and the leaching requirement model LrSAO-e (for reactive salt), were verified using a new set of data.

The new data are the results of water and soil analysis carried out in a pilot farm during leaching reclamation and by sampling an extension area in Al Hassa, Saudi Arabia.

The steady-state SAO model was, originally, based on the changes in irrigation water composition, which occurred due to molecular-water loss, mineral precipitation and dissolution, K´ fixation, NaCl apparent retention, MgSO4 o formation, and biological formation of HCO3 .

Better model predictions were obtained by including CaSO4 o formation, and soil-Mg hydrolysis.

Based on SAO results (EC of soil solution vs concentration factor) the LrSAO-e model for reactive salt was verified and was able to predict, successfully, the (AE / ECi vs Lr) experimental data, where AE is the crop salt tolerance threshold and ECi is salinity of irrigation water.

The LrSAO-e model was incorporated with a CROP response code into a water management DRAINKIM program able to predict list of suitable crops, crop yields, leaching requirements, and other management parameters for irrigation-drainage waters.

The use of DRAINKIM for the assessment of different scenarios for the re-utilization of drainage water and the selection of management options was demonstrated.