湿地地表水与地下水交互作用可视化试验研究

Experimental Study on Visualization of Interaction Between Surface Water and Groundwater in Wetland

湿地独特的地形结构,导致地表水与地下水交互作用复杂,传统现场试验、室内模型试验和数值模拟难以很好地刻画湿地地表水与地下水的交互作用。对此,基于透明土原理,利用水凝胶颗粒和蒸馏水,配制成饱和透明土,构建湿地结构可视化模型,并采用粒子图像测速(PIV)技术获得不同试验工况下的湿地内部流场图;结合数字图像处理技术,揭示湿地内部水流的流动特性。结果表明,湿地丰水期时主要以地表水补给地下水为主,降雨量增大,河流对湿地两岸入渗效果影响区域增大,湿地表面积水深度由0 mm增加至2.5 mm;随着降雨量增大,湿地地表水补给到地下水系统的时间越短,降雨量为10 mm是降雨量为20 mm地表水补给到地下水系统时间的1.2倍。湿地枯水期时主要以地下水补给地表水为主,随着地下水压力增大,地下水向上补给的入渗速率依次增大,相同时间内地下水向上补给的距离依次增加。

The unique topographic structure of wetlands leads to complex interactions between surface water and groundwater.Traditional field tests,indoor model tests and numerical simulations are difficult to describe the interaction between surface water and groundwater in wetlands.To solve this problem,based on the principle of transparent soil,this paper uses hydrogel particles and distilled water to prepare saturated transparent soil and construct a visual model of wetland structure.In addition,Particle Image Velocimetry(PIV)technology is used to obtain the internal flow field of wetland under different test conditions.Combined with digital image processing technology,the flow characteristics of water inside the wetland are revealed.The results show that during the wetland period,the groundwater is mainly supplied by surface water.As the rainfall increases,the area of river infiltration effect on both sides of the wetland increases,and wetland surface water depth increased from 0 mm to 2.5 mm.As rainfall increases,the time for wetland surface water to recharge the groundwater system is shorter.A rainfall of 10 mm is 1.2 times longer than that of 20 mm of rainfall for surface water to recharge the groundwater system.During the wetland dry season,the surface water is mainly supplied by groundwater.As the pressure of groundwater increases,the infiltration rate of upward recharge and the distance of upward recharge by groundwater within the same period of time increase sequentially.