Simulation of Heterogeneous Soil Salinity under Unsteady Condition from a Line Source

Document Type : Complete scientific research article

Authors

1 MSc Student, University of Guilan

2 Assistant professor, University of Guilan

3 Researcher at Research center for agriculture and natural resources

Abstract

Limitation of water resources has led to unusual waters applications and the use of high-efficiency irrigation systems such as drip irrigation in some areas. The mismanagement of water resources has caused increases the accumulation of salts in the soil. Due to the executive limitations of field experiments such as high cost and time-consuming, using of simulator models for studying different management scenarios is recommended. Purpose of this research is evaluation of the salt transport in heterogeneous heavy soil and unsteady conditions with estimating hydraulic and solute transport parameters using inverse solution with the HYDRUS-2D model. Drip irrigation system was applied as a line source and was done with water salinity of 1.279, 2.5 and 5 dS/m. Soil profiles were dug to 40cm depth and networked, 48 hours after irrigation. Sampling from beneath the tape and horizontal distance of 20 cm from the tape was used to determine the salinity of the soil saturation extract. ECe observed values were compared with ECe simulated values using statistical indices i.e. nRMSE and CRM. Simulated soil salinity values were slightly lower than the observed values. Ranges of nRMSE for beneath the tape and the horizontal distance were between 2.79-18.49% and 3.084-20%, respectively. Simulations placed in good to excellent category. Ranges of CRM for beneath the tape were between -0.049 and 0.097 and the horizontal distance were between -0.065 and 0.081. Thus, this model can be used as a suitable tool for the design and management of drip irrigation with saline and brackish water.

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