Collaborative Research: Suspended Sediment Transport in Karst

[125551]虽然从直观上看，岩溶含水层比多孔介质含水层携带更多的泥沙，但由于其管道较大，流速较快，因此很少有研究试图量化岩溶中泥沙的输运。了解沉积物的运移是很重要的，原因有很多。首先，沉积物可以加强污染物的运输，这些污染物是通过附着在沉积物上而被动员起来的。其次，沉积物的流动性也反映了细菌和病毒的潜在流动性，这是评价地下水质量所关注的问题。第三，沉积物的流动性是喀斯特速度和运移路径的衡量标准，这是一个复杂的问题，涉及不同水库的混合，很难量化。这项研究将通过测量一组喀斯特含水层在一年中和几种不同类型的风暴事件期间的沉积物运输，来解决沉积物运输如何随季节和不同风暴事件而变化。风暴事件将包括小风暴和大风暴，加上有湿和干先决条件的风暴。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，将安装连续记录仪来监测电导率、流量和浊度，以记录季节变化和风暴之前的条件。此外，雨水采样器将在选定的风暴事件期间自动触发采样。每月和风暴期间收集的样本将被分析详细的水化学、沉积物组成和沉积物大小分布。将努力模拟喀斯特含水层内泥沙运动的运输过程。将实地考察与模拟相结合来评估泥沙运移的控制因素，利用泥沙运移隐含的混合比对不同的喀斯特系统进行分类。解开不同水库的混合在喀斯特和非喀斯特系统中都很重要，这项研究将有助于展示时间异质性（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末端成员系统（喀斯特）和量化理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.