International Research Fellowship Program: Variable Flow and Sediment Transport in Speleogenetic Models

国际研究奖学金计划使美国科学家和工程师能够在国外进行9到24个月的研究。该计划的奖项提供了联合研究的机会，并利用国外独特或互补的设施、专业知识和实验条件。该奖项将支持Matthew Covington博士与斯洛文尼亚波斯托伊纳喀斯特研究所的Franci Gabrovsek博士合作的为期24个月的研究奖学金。大约20%-25%的全球人口依赖来自岩溶含水层的地下水。尽管这种资源很重要，但由于缺乏对给定含水层中岩溶管道的位置和几何形状的了解，现有的模型不能准确预测流量和污染物运移。近年来发展了计算岩溶含水层形成和演化的洞穴成因模型。然而，目前的模型不能考虑实际管道系统中发生的许多过程，这些模型与现场数据之间的联系也是有限的。这项工作的目的是：1)研究变流量对输导演化的影响；2)建立泥沙输移及其对洞穴形成的影响的模拟框架；3)将洞穴发生模型的适用性扩展到实际的岩溶系统。这些目的通过野外工作、管道流动网络建模和修改先前由主机构建的洞穴成因模型来实现。PI正在使用雨水管理模型(SWMM)开发一套理想的洞穴管道网络系统，并使用后处理来计算溶解速率和热量传输。这些研究探索了模拟输出如何随管道几何测量、粗糙度和充注量的变化而变化。在典型的斯洛文尼亚喀斯特的两个不同的洞穴系统中都有持续的监测点。这些站点位于已知导管系统的长度上，可以记录深度、温度和传导性。建议的项目使用SWMM来帮助解释这些数据，并探索不同的水流和泥沙输送对管道演变的影响。PI正在开发算法，以将这些影响包括在洞穴发生模型中。建议的研究扩展了洞穴成因模型的适用性，包括可变水流、泥沙输移和机械侵蚀。由于沉积物运移对污染物运移和洞穴生态都至关重要，这项研究将洞穴发生与这些领域联系起来。此外，洞穴沉积物提供了宝贵的年龄记录，扩展的模型将允许探索通道成因和沉积物沉积之间的关系。

0754495CovingtonThe International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.This award will support a twenty-four month research fellowship by Dr. Matthew Covington to work with Dr. Franci Gabrovsek at Karst Research Institute in Postojna, Slovenia.Roughly 20-25% of the global population relies on groundwater from karsticaquifers. Despite the importance of this resource, current models do not accurately predict flow rates and contaminant transport due to lack of knowledge concerning the location and geometry of the karst conduits in a given aquifer.Speleogenetic models, which calculate the formation and evolution of karst aquifers, have been developed in recent years. However, current models do notaccount for many of the processes that occur in real conduit systems, and connections between these models and field data are limited. The purposes of this work are to: 1) study the effects of variable flow on the evolution of conduits, 2) develop a framework for modeling sediment transport and its effects on speleogenesis, and 3) expand the applicability of speleogenetic models to real karstic systems. These purposes are addressed through field work, conduit flow network modeling, and the modification of a speleogenetic model previously constructed by the host. The PI is developing a set of idealized cave conduit network systems using the Storm Water Management Model (SWMM) and using post-processing to calculate dissolution rates and heat transport. These explore how simulated outputs vary with conduit geometery, roughness, and recharge. Continuous monitoring sites are in place in two different cave systems in the classical Slovenian karst. These sites are located along the length of known conduit systems and can record depth, temperature, and conductivity. The proposed project uses the SWMM to aid in the interpretation of these data and to explore the effects of variable flow and sediment transport on conduit evolution. The PI is developing algorithms for including these effects within speleogenetic models. The proposed study expands the applicability of speleogenetic models by including variable flow, sediment transport, and mechanical erosion. Because sediment transport is crucial for both contaminant transport and cave ecology, the study connects speleogenesis with these fields. Furthermore, cave sediments provide valuable age records, and the extended model will allow explorations of the relationship between passage genesis and sediment deposition.