Abstract

Bank filtration (BF) is an established indirect water-treatment technology. The quality of water gained via BF depends on the subsurface capture zone, the mixing ratio (river water versus ambient groundwater), spatial and temporal distribution of subsurface travel times, and subsurface temperature patterns. Surface-water infiltration into the adjacent aquifer is determined by the local hydraulic gradient and riverbed permeability, which could be altered by natural clogging, scouring and artificial decolmation processes. The seasonal behaviour of a BF system in Germany, and its development during and about 6 months after decolmation (canal reconstruction), was observed with a long-term monitoring programme. To quantify the spatial and temporal variation in the BF system, a transient flow and heat transport model was implemented and two model scenarios, ‘with’ and ‘without’ canal reconstruction, were generated. Overall, the simulated water heads and temperatures matched those observed. Increased hydraulic connection between the canal and aquifer caused by the canal reconstruction led to an increase of ~23% in the already high share of BF water abstracted by the nearby waterworks. Subsurface travel-time distribution substantially shifted towards shorter travel times. Flow paths with travel times <200 days increased by ~10% and those with <300 days by 15%. Generally, the periodic temperature signal, and the summer and winter temperature extrema, increased and penetrated deeper into the aquifer. The joint hydrological and thermal effects caused by the canal reconstruction might increase the potential of biodegradable compounds to further penetrate into the aquifer, also by potentially affecting the redox zonation in the aquifer.

中文翻译：

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通过流动和热传递的瞬态三维建模评估河流重建对堤岸过滤过程中地下水流量的影响

摘要

银行过滤（BF）是一项成熟的间接水处理技术。通过高炉获得的水的质量取决于地下捕获区，混合比（河流水与环境地下水），地下旅行时间的时空分布以及地下温度模式。进入相邻含水层的地表水入渗量取决于当地的水力梯度和河床渗透率，这可以通过自然堵塞，冲刷和人工沉降的方法来改变。通过一项长期监测计划，观察到了德国高炉系统的季节性行为，以及在拔除大肠（运河重建）期间和之后约6个月的发展情况。为了量化高炉系统的时空变化，实施了瞬态流动和热传输模型，并生成了“有”和“无”运河重建的两个模型方案。总体而言，模拟的水头和温度与观察到的相匹配。运河重建造成的运河与蓄水层之间的水力联系增加，导致附近自来水厂抽取的高炉水比例已经提高了约23％。地下旅行时间分布基本上转向了更短的旅行时间。时间<200天的流路增加了〜10％，而<300天的流路增加了15％。通常，周期性的温度信号以及夏季和冬季的温度极值都增加并深入到含水层中。