Collaborative Research: Suspended Sediment Transport in Karst

尽管从直觉上看，岩溶含水层将比多孔介质含水层携带更多的泥沙，但由于管道较大，流速较快，试图量化岩溶中泥沙运移的研究相对较少。了解泥沙运移具有重要意义，原因有很多。首先，沉积物可以加强污染物的运输，这些污染物通过附着在沉积物上而被动员起来。其次，沉积物的流动性也反映了细菌和病毒的潜在流动性，这在评估地下水质量时是值得关注的。第三，泥沙的流动性是对岩溶速度和运移路径的衡量，这是一个复杂的问题，涉及来自不同水库的混合，很难量化。这项研究将通过测量一组岩溶含水层在一年中和几种不同类型风暴事件期间的泥沙运移，说明泥沙运移如何随季节和不同的风暴事件而变化。风暴事件将包括小风暴和大风暴，以及之前有潮湿和干燥条件的风暴。选择了三个不同的岩溶含水层，包括高、中、低流量系统。在每个地点，将安装连续记录仪，监测电导率、流量和浑浊度，以记录风暴的季节变化和前兆条件。此外，在选定的风暴事件期间，雨水采样器将自动触发采样。每月和风暴期间收集的样本将被分析，以了解详细的水化学、沉积物成分和沉积物粒度分布。将努力模拟岩溶含水层内泥沙运动的运移过程。将结合实地工作和模拟来评估对泥沙运移的控制，以利用泥沙运移所隐含的混合比对不同的岩溶系统进行分类。解开来自不同储集层的混合在岩溶和非岩溶系统中都很重要，这项研究将有助于说明时间不均质性(风暴事件之间的变化，而不仅仅是风暴事件内部的变化)如何为系统的内部结构提供线索。这项工作将通过研究终端成员系统(岩溶)并量化了解系统响应所需的测量类型，来证明水文系统中时间异质性的重要性。

0125551WhiteAlthough it seems intuitively obvious that karst aquifers will carry more sediment than porous media aquifers, because of the large conduits and faster velocities, relatively few studies have tried to quantify sediment transport in karst. Understanding sediment transport is important for a number of reasons. First, sediment may enhance transport of contaminants that are mobilized by attaching to sediment. Second, the mobility of sediment also reflects the potential mobility of bacteria and viruses, which are of concern in evaluating groundwater quality. And third, the mobility of sediment is a measure of velocities and transport pathways in karst, a complex issue involving mixing from different reservoirs, which is difficult to quantify. This research will address how sediment transport varies with seasons and different storm events by measuring sediment transport in a set of karst aquifers over the course of a year and during several different types of storm events. Storm events will include small and large storms, plus storms with wet and dry antecedent conditions. Three distinct karst aquifers have been selected that include a high, medium, and low discharge system. At each site, continuous loggers will be installed to monitor conductance, discharge, and turbidity to record seasonal variation and antecedent conditions for storms. In additional, stormwater samplers will automatically trigger to sample during the selected storm events. Samples collected monthly and during storms will be analyzed for detailed water chemistry, sediment composition, and sediment size distribution. Efforts will be made to model the transport processes for sediment movement within karst aquifers. The combination of fieldwork and modeling to assess the controls on sediment transport will be used to classify the different karst systems using the mixing ratios implied by sediment transport. Unraveling mixing from different reservoirs is important in both karst and non-karst systems, and this study will help show how temporal heterogeneity (changes between storm events, not just within storm events) can provide clues to the internal structure of a system. This work will demonstrate the importance of temporal heterogeneity in hydrologic systems by studying an end-member system (karst) and quantifying the types of measurements needed to understand system response.