Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Titre : Optimization of subsurface drip irrigation under saline conditions

Auteur : Arevalo, Abraham

Etablissement de soutenance : Ben-Gurion University of the Negev

Grade : Master of Science (MS) 2016

Résumé
The development of efficient subsurface drip irrigation systems (SDI) has contributed to improved management of declining water resources for agricultural production and irrigation with low quality waters. The objectives of this study were to calibrate and validate the soil-water-plant numerical model HYDRUS (2D/3D), for a subsurface drip irrigation system under saline conditions for a potato crop, and to optimize the irrigation amount, salt storage, salt drainage and evapotranspiration ratio (ER), defined as the ratio between actual and potential accumulated modeled evapotranspiration. A field experiment was conducted with three irrigation levels (60, 80 and 100% of the reference evapotranspiration) in four replications using subsurface drippers. Soil water content (v) and bulk salinity (p) were measured along the season using Decagon’s GS3 sensors. The sensors were calibrated using dielectric permittivity values to eliminate the effect of salinity. Soil hydraulic properties were estimated by soil samples and using the inverse method in HYDRUS (2D/3D). Two complementary methods were used in order to calibrate the osmotic head reduction and root distribution parameters. The first method used descreet data measured from soil samples and the second method used continuous data taken with sensors located in the field. The calibration was acceptable for v and p for both calibration methods in all treatments, except for the p at the 60% and 100% treatments in the calibration using the sensor data, due to sensor sensitivity to high salinity. The validation was performed using 10 days of data from the sensors. It was acceptable for v for the first and second treatments (60% and 80%), and good for the third treatment. The validation for p was unsatisfactory in the first and third treatments and acceptable in the second treatment. The salt storage and the salt drainage amount were influenced by the irrigation treatment because the salt storage was higher in the first and second treatments and lower and the third treatment, while the opposite happened for the salt drainage amount.

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