Conclusions

The dynamics of soil water movement and recharge to groundwater were studied in the Yellow River irrigation area during the maize growing season by combined physical and isotopic techniques. The results indicate that the soil at 0-50 depth was mainly influenced by precipitation infiltration and evaporation. The entire profile of soil was affected by rapid infiltration from irrigation while the soil water mainly moved downward in the mode of piston flow. The maize root system had reached the depth of 100cm during the tasseling periods according to SWPs decrease from 70 to 100cm. The infiltration and capillary rise were totally 544.6 mm in 2020, which were similar with that in 2019. However, the total deep percolation(156.6mm) was smaller than that in 2019 due to the higher ET. It can be concluded that the leakage of ditch was the major recharge resource of groundwater for the fast water table rise.
The observed temporal variations of soil water in multiple soil layers in two different land covers contribute toward the understanding of the mechanism of soil water and recharge to groundwater in the irrigation area of arid and semi-arid climates. The results provided critical information for soil and water management to improve irrigation efficiency and water use efficiency.