Abstract: Desert riparian forests are important ecosystems in arid regions,and the recharge of shallow groundwater through the intermittent river flow is the primary water source for the plants in these riparian forests.Based on groundwater elevation data collected from the riparian forest of Ejina Oasis in northwest China,which achieves high spatiotemporal resolution,we analyzed the dynamics of the shallow groundwater and its response to river discharge.We found that groundwater levels declined during the growing season and rose when plants stopped growing.We also observed a diurnal fluctuation,with water levels rising during the daytime and declining at night.The amplitude of this diurnal fluctuation depended on the vegetation cover and the intensity of evapotranspiration during different periods of plant growth.Infiltrating river water is the dominant recharge source of the shallow groundwater in the lower reach of the Heihe River.During periods of water transfer,the groundwater response times increased,and the magnitude of groundwater uplift declined with distance from the river.Gross discharge,discharge duration,and daily average discharge were the main factors governing groundwater recharge.River seepage was mostly lost as evapotranspiration.After six periods of water transfer in the Heihe River from 2013 to 2015,the average ratio of groundwater recharge to the sum of groundwater recharge and evapotranspiration was 23.6%.

Key words: desert riparian forests, groundwater level, river leakage, groundwater recharge