| Summary: | This paper deals with the movement of water in a natural unsaturated zone, focusing on infiltration-redistribution system.
Infiltration refers to the downward movement of water due to the gravitational force and redistribution defines the upward
movement of water due to the capillary rise. Under natural conditions, the movement of water through an infiltrationredistribution
depended upon the relations among water content, hydraulic conductivity and tension of soil pore. Various
combinations of water balance concepts, Richards’ equation, soil-physics theory and capillary height concepts were applied
to mathematically model the movement of water through infiltration-redistribution system. The accuracy and computational
efficiency of the developed model were evaluated for the case study. Besides the laboratory scale sand/soil columns with the
inner diameter of 10.4 cm were investigated in order to provide the supporting data for model calibration. Sand/soil layers
were packed with a bulk density of 1.80 and 1.25 g/cm3, respectively. The infiltration was sprayed uniformly at the soil
surface with the constant rate of 66.1 and 7.18 cm3/h for sand and soil columns, respectively. The redistribution process was
developed by which water arriving at the column base enter to the sand/soil column due to capillary rise. The laboratory
observations were simulated using the developed model. The results indicate that the developed model could well estimate
the movement of water in the infiltration-redistribution system that observed in the case study and the experiments.
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