会仙喀斯特湿地地下水分水岭移动特征研究

The Moving Characteristics of the Groundwater Divide in Huixian Karst Wetland

会仙喀斯特湿地分布于漓江流域和柳江流域的分水岭地带。该湿地仅由地下水补给,地下水水位对维持该湿地生态系统起着决定性的作用。2019年,在会仙湿地具有代表性的6个水位观测点(4个地下水水位观测点,2个地表水水位观测点),利用压力传导型水位计,自动记录了一个水文年的地下水和地表水水位。研究结果表明,雨季与枯季会仙湿地的地下水水位存在明显差异,地下水水位的变化幅度最大可达2.5 m;核心区的地下水分水岭具有可移动性,在雨季降水量增加时,其向东移动,在雨季降水量减小和枯季水位下降时,其向西移动;暴雨过后,地下水和地表水水位都迅速回落至暴雨前的水平,地表水体和会仙湿地地下水系统都没有起到储蓄洪水的作用;枯水期地下水水位继续下降,并且低于149 m,导致枯水期会仙湿地严重萎缩;在枯水期,通过外部输水补给,保持会仙湿地的地下水水位不低于149 m,是减缓该湿地退化的关键措施。

Huixian karst wetland is located at the boundary area of Li River and Liu River.The wetland is only recharged by groundwater,so the changes of groundwater level have key influence on maintaining the wetland ecosystem.The dynamic monitoring of groundwater and surface water levels with pressure probes were conducted at 6 observation stations for the whole hydrological year of 2019,4 stations for groundwater and 2 stations for surface water.The significant changes of groundwater level were found between rainy and dry season.The results showed that the difference of groundwater level between rainy and dry seasons could be up to 2.5 m.In the core area of the wetland,the groundwater divide was found movable.It moved to the east as the rainfall increased in rainy season,and moved to the west after the rainfall days or in dry season.The surface water and groundwater level recovered rapidly,and reached the state as the pre-storm period.This proved that the wetland had weak roles of detaining flood,and the storage functions were not performed by the surface water and groundwater.The water level being less than 149 m in the dry season could result in severe degradation of the wetland.The artificial recharge is the key measure to keep the wetland water level to be above 149 m and slow down the deterioration of the wetland ecosystem.