Groundwater-surface water interactions in the Baiyangdian wetland, Xiong'an New Area and its impact on reed land

It is of great significance to find out the interaction between surface water and groundwater for wetland ecological protection and restoration. A multiply tracers approach including water level monitoring, oxygen and hydrogen isotopes analysis and temperature tracing was used to identify the location, magnitude and depth of surface water leakage to shallow groundwater. As also, a brief study of relationship between reed land and water level and groundwater depth was conducted. The results show that the scope of leakage water is controlled by geological and hydrogeological conditions. The depth is about 20m and the length from lake shore varies spatially. The recharge sources of surrounding shallow groundwater are atmospheric rainfall and surface water, of which the recharge proportion of surface water leakage is 0-90.5%. The leakage rate is from 0.01 to 0.59 mm/d inside the wetland and has a strong relationship with the depth of the shallow aquifer. The less the burial depth, the more conducive to surface water leakage. There was a significant relationship between reed land and the average surface water level from 1976 to 2020. When the surface water level was between 6.3 to 6.8 m, the reed land was the largest. When the water level was less than 6.3 m, the reed land had a positive correlation with it, while the reed land area decreased as the water level was higher than 6.8 m. Groundwater depth had an obvious relationship with surface water level where reeds grew. During the growing season, it showed that groundwater depth was suitable for reeds growth most of the time. In order to prompt reed growth, it is suggested that artificial recharge should be conducted before monsoon season to lower groundwater depth. The conclusions can provide basic supports for water recharge, leakage resisting and eco-environment protecting in the Baiyangdian wetland.