Dynamic characteristics and equilibrium of water level of the karst groundwater system beneath the Huixian wetland

The Huixian wetland is the largest karst wetland in China. In the past half century, due to the unreasonable development and utilization of human beings, the water area of this wetland has shrunk severely. Research on groundwater dynamics and water balance in the Huixian wetland is of great significance for maintaining ecological functions, water resources management, and protection of the wetland. This paper first divides the Huixian wetland into two groundwater systems based on the hydrogeological conditions，namely the Mamianshiziyan system and Mudong river (lake) dispersed excretion system. Then, the recharge, runoff, drainage characteristics and groundwater dynamic characteristics of the two groundwater systems are analyzed separately. Finally, the equilibrium analysis of two groundwater systems is carried out. The results show that the water level fluctuation of the Huixian wetland is obviously affected by rainfall, the water level of each monitoring point varies unevenly and the response times of the water level to rainfall are inconsistent. The storage capacity of the groundwater system in the Huixian wetland is -61,900 m3, which is related to the drought in the later period of the equilibrium period. The main recharge source of karst groundwater in the wetland is atmospheric precipitation infiltration, the main excretion manner is submarine runoff and evaporation. The Huixian wetland karst groundwater system has certain water storage and storage functions, but its storage capacity is limited. To maintain the ecological function of the wetland for a long time, the wetland storage capacity should be strengthened. It can start from reducing the evapotranspiration and exploitation of the wetland, coupling with the restoration and reconstruction of the wetland ecological environment, improving the water conservation capacity, and keeping the wetland water level within a stable change interval.