Böhnke R, Geyer S, Kowski P
UFZ Centre for Environmental Research Leipzig-Halle, Department of Hydrogeology, Germany.
Isotopes Environ Health Stud. 2002 Mar;38(1):1-13. doi: 10.1080/10256010208033304.
We examined a floodplain area in the middle section of the river Elbe Valley with regard to hydrogeological and hydrological processes using isotopic methods. Over two years, river water and groundwater have been analysed for temporal and spatial chemical and isotopic (delta2H and delta18O) changes. By these methods we assessed the flow dynamics of the river-groundwater infiltration system. At low and mean river stages there is a general hydraulic gradient from the higher areas at the margin of the valley towards the floodplain. During floods river water infiltrates into the adjacent aquifer not primarily through the river banks but first through surface water inflow from north to south, via depressions and gullies from the back of the floodplain. The early stage of river water infiltration is characterized by a sharp decrease in conductivity and in concentrations of SO4(2-) and Cl- in the hydraulically connected shallow aquifer. delta2H and delta18O values show a similar tendency. We observed a significant minimum in stable isotope ratios during the flood in March 1999. Using a simple mixing equation it was calculated that the groundwater in the upper, shallow aquifer consists of around 70% river water in the transition zone (well 13) during flooding.
我们运用同位素方法，对易北河河谷中段的洪泛区进行了水文地质和水文过程方面的研究。在两年时间里，对河水和地下水进行了分析，以研究其化学和同位素（δ²H和δ¹⁸O）的时空变化。通过这些方法，我们评估了河水 - 地下水入渗系统的流动动态。在河流低水位和中水位时，一般存在从河谷边缘较高区域向洪泛区的水力梯度。在洪水期间，河水并非主要通过河岸渗入相邻含水层，而是首先通过从北向南的地表水径流，经由洪泛区后部的洼地和沟壑流入。河水入渗的早期阶段，水力连通的浅层含水层中的电导率以及SO₄²⁻和Cl⁻浓度会急剧下降。δ²H和δ¹⁸O值呈现出类似趋势。我们在1999年3月的洪水期间观测到稳定同位素比率出现显著最小值。运用简单的混合方程计算得出，在洪水期间，上部浅层含水层中的地下水在过渡带（13号井）约由70%的河水组成。
