Estimation of solute transport and storage parameters in a stream with anthropogenically produced unsteady flow and industrial bromide input
Estimation of solute transport and storage parameters in a stream with anthropogenically produced unsteady flow and industrial bromide input
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利用人为产生的不稳定流和工业溴化物输入来估计流中的溶质传输和存储参数
DOI：
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发表时间：
2004
期刊：
影响因子：
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通讯作者：
C. Welty
中科院分区：
文献类型：
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作者：
R. Ryan;A. Packman;C. Welty
我们使用了人为的示踪信号，以评估下游的溶质输运和存储在谷溪，宾夕法尼亚州费城附近的60平方公里的流域流，这是城市化和eregenically引起的不稳定流。来自废弃选矿厂的含溴地下水通过一系列明确的渗漏和泉水进入Valley Creek的上游，在Valley Creek中产生稳定且显著的溴化物浓度。此外，在研究时，位于流域中心附近的一个采石场将累积的地下水渗漏周期性地排入河流。采石场排放降低了主流中的溴化物浓度，并在采石场下游的流中溴化物浓度中产生了周期性。我们使用这些变化，在环境中的溴化物浓度，以评估溶质的混合和运输谷溪。我们应用美国地质勘探局代码奥蒂斯分析溶质平流，分散，瞬态存储，地下水流入超过7.5公里的河段。为了将奥蒂斯应用于非稳定流条件，我们独立地模拟了流动循环期间流条件的变化，然后使用纵向分散系数（D）、瞬时储存交换率（α）和瞬时储存面积（As/A）的时间和平均值模拟溶质运移。D的校准值范围为0.5 m2 s-1至1.4 m2 s-1，As/A的范围为0.03至1.3，α的范围为8.7 × 10 - 6 s-1至1.0 × 10 - 2 s-1。很好地模拟了所观察到的流中溴化物浓度的时间变化。所观察到的瞬态存储参数反映了三个测试河段的结构差异。中游的溶质储存主要是由残存的水工建筑物产生的河道内储存，而其他两个河段的溶质运移反映了上下游河段床沙特性的差异。然而，过度参数化的模式和高敏感性的分散系数，使其难以评估的瞬态存储或hyporheic交换的大小。
We used an anthropogenic tracer signal to evaluate downstream solute transport and storage in Valley Creek, a 60 km2 watershed stream near Philadelphia, Pennsylvania, that is subject to urbanization and anthropogenically induced unsteady flow. Bromide‐bearing groundwater from an abandoned mineral processing plant enters the upstream reach of Valley Creek through a series of well‐defined seeps and springs, producing a steady and significant concentration of bromide in Valley Creek. In addition, at the time of the study, a quarry located near the center of the watershed discharged accumulated groundwater seepage to the stream on a cyclical basis. The quarry discharge reduced the bromide concentration in the main stream and produced a periodicity in the in‐stream bromide concentration downstream of the quarry. We used these variations in the ambient bromide concentration to assess solute mixing and transport in Valley Creek. We applied the USGS code OTIS to analyze solute advection, dispersion, transient storage, and groundwater inflow over a 7.5 km stream reach. To apply OTIS for unsteady flow conditions, we independently modeled the variation of stream conditions during a flow cycle and then simulated solute transport using temporal and reach average values of the longitudinal dispersion coefficient (D), transient storage exchange rate (α), and transient storage area (As/A). Calibrated values of D ranged from 0.5 m2 s−1 to 1.4 m2 s−1, As/A ranged from 0.03 to 1.3, and α ranged from 8.7 × 10−6 s−1 to 1.0 × 10−2 s−1. Observed temporal variability in the in‐stream bromide concentration was simulated well. The observed transient storage parameters reflect differences in the structure of the three test reaches. Solute storage in the middle reach was dominated by in‐stream storage produced by relict hydraulic structures, while solute transport in the other two reaches reflected differences in bed sediment characteristics between upstream and downstream reaches. However, overparameterization of the model and high sensitivity to the dispersion coefficient made it difficult to assess the magnitude of transient storage or hyporheic exchange.