A study of groundwater recharge under different irrigation conditions in the middle reaches of the Heihe River

Rainfall and irrigation are important sources of recharge for shallow groundwater in the middle reaches of Heihe River . There is no mature monitoring method and empirical data for evaluating infiltration recharge by introducing empirical parameters for a long time. In this paper, artificial bromide tracer method is used to study groundwater infiltration under different irrigation conditions and different depths in the middle reaches of the Heihe River. The results show that under the condition of rainfall in the study area, the annual average transport distance of the peak content of bromine ion in the vadose zone is 21.25 cm, the annual average recharge is 11.93 mm, and the infiltration recharge coefficient is 0.1. Under the condition of large irrigation amount, the average annual migration distance of the peak content of bromine ion in the vadose zone is 86.51 cm, the average annual recharge is 148.7 mm, and the infiltration recharge coefficient is 0.16. Under the condition of small irrigation amount, the average annual migration distance of the peak content of bromine ion in the vadose zone is 46.35 cm, the average annual the downward zone of unidirectional infiltration of water in the unsaturated zone, which is generally suitable in the recharge is 53.81 mm, and the infiltration recharge coefficient is 0.07. Under drip irrigation, the average annual moving distance of the peak value of bromine ion content in the vadose zone is 41.72 cm, the average annual supply is 52.6 mm, and the infiltration recharge coefficient is 0.11. Artificial bromide tracers should be placed in northwest inland basin more than 3 m. The results can provide parameters for the evaluation of groundwater resources in the Heihe River Basin, which is of great significance for scientific understanding of groundwater resources and rational development and utilization in northwest inland basins.