半干旱草原内陆河潜流交换研究——以内蒙古锡林河为例

Research on the Hyporheic Exchange in Semi-Arid Grassland Inland Rivers:Taking Xilin River in Inner Mongolia as an Example

潜流交换对于地表水和地下水水质以及河流廊道的生态环境有重要作用。针对半干旱草原河流潜流交换作用研究不足的现状,选取锡林河作为典型草原河流,利用水动力学法和温度示踪法对锡林河上游试验河段的垂向潜流交换过程进行定量研究,并讨论了两种方法的适用性。结果表明,试验期间主要为地表水补给地下水,垂向潜流交换主要发生在河床表面以下20~100 cm。受砂质河床流动性较大和空间异质性的影响,河道不同位置的潜流交换速率及其对降雨的响应各不相同。水动力学法与温度示踪振幅法得到的河段垂向潜流交换速率具有一致性:分别为-0.2~0.4、-0.1~0.4 m/d。相比于易受河床形态和水动力学特性影响的水动力学法,温度示踪法具有准确、便捷的特点,更适用于半干旱草原河流的潜流交换研究。

Hyporheic exchange plays an important role in surface water and groundwater quality and the ecological environment of river corridors.The Xilin River is chosen as a typical grassland river to address scarce research on the hyporheic exchange in semi-arid grassland rivers.Both the hydrodynamic and temperature tracer method are used to quantify the process of vertical hyporheic exchange in the upper section of the Xilin River.The applicability of the two methods is also discussed.The results indicate that surface water mainly discharged to groundwater during the experiment period.Vertical hyporheic exchange occurs mainly 20~100 cm below the riverbed surface.Under the influence of the fluidity and inhomogeneity of the sandy riverbed,the process of hyporheic exchange and its response to rainfall vary at different locations of the river channel.Both hydrodynamic and temperature-tracer methods obtain consistent vertical rates of hyporheic exchange,i.e.,-0.2~0.4 and-0.1~0.4 m/d.Compared with the hydrodynamic method,which can be easily influenced by the morphology and hydrodynamic characteristics of the riverbed,the temperature tracer method is accurate and convenient,and more suitable for the study of hyporheic exchange in semi-arid grassland rivers.