Collaborative Research: Can Human-Induced Turbidity Currents Enable Sustainability of Freshwater Reservoirs?

水库在美国和世界范围内提供了许多社会服务，包括洪水控制、水力发电、饮用水和农业灌溉。尽管水库发挥着至关重要的作用，但由于土地利用和气候变化加剧了自然和工程地表水系统中的土壤侵蚀、沉积物运输和沉积，水库正在逐渐被沉积物填满。在美国几乎没有合适的地点建造新水坝，因此强调需要对现有水库进行经济有效的管理。2024年，美国陆军工程兵团（USACE）和堪萨斯州计划在堪萨斯州的一个联邦水库试点测试一种新的注水疏浚（WID）工艺（一种未经测试但可能具有变革性的方法），目的是诱导浊度流并将被困的水库沉积物出口到下游水道，这对于解决全球关注的水库沉积及其对水安全的影响至关重要。然而，关于WID恢复水库泥沙储存能力的能力、对湖内水质的环境影响以及对河道形态和水生生态系统的下游影响等关键问题仍然存在。为了解决这些知识差距，该项目的主要研究者（pi）建议利用USACE-Kansas WID现场测试来收集和分析沉积物、营养物质和水生物种计数数据，目的是在水库实施WID过程后，产生有关运输效率、机制和环境响应的基础科学和工程知识。如果WID被证明是可行的，对下游河流生态系统的影响最小，那么这个项目的成功完成将通过产生新的数据和基础知识来造福社会，这些数据和知识可以用于全球各地的水库，改变沉积物管理，并降低与现有疏浚技术相关的成本。通过学生教育和培训，包括堪萨斯大学的一名本科生和一名研究生以及堪萨斯州立大学的两名本科生和一名研究生的指导，将为社会带来额外的好处。现有的水库沉积物管理技术的有效性有限，因为它们(1)不能恢复自然下游沉积物的连续性，(2)需要运输、储存和处置疏浚的材料，(3)实施成本高昂。注水疏浚（WID）过程的基本前提是向水库床层喷射一股流体，将沉积物带入上覆水域，并启动密度流（类似于水下雪崩），将储存的床层沉积物动员到水库出口。虽然WID已成功地应用于港口和河流，但尚未在水库中进行测试，因此提出了有关其潜在功效和环境影响的关键问题。本项目将填补这些知识空白。该研究的具体目标是：1)利用高频浊度传感数据和计算流体动力学建模，评估人为浊度流在水库中传播的物理机制；2)在WID现场测试之前、期间和之后，利用原位物理化学传感器和实验室实验，通过监测热分层和氧化还原条件，评估水库水质的变化；3)在WID现场试验之前、期间和之后评估河道和漫滩的增积率；4)持续评估鱼类和大型无脊椎动物群落对沉积物释放的响应，以及在整个WID示范项目中引起的水质和栖息地的生物、化学和物理变化。这项研究的成功完成可能会改变水库的管理方式，有可能延长全球大型储水基础设施的使用寿命。为了实现该项目的教育和培训目标，首席研究员（pi）将与堪萨斯大学（KU）自我工程领导研究员（Self）计划合作，为大学生开发和提供一个研讨会，让他们使用大型环境数据集进行实践研究，并培养科学交流技能，最终向堪萨斯州和陆军工程兵团进行演示。此外，pi计划将这项研究的结果整合到堪萨斯大学和堪萨斯州立大学的相关课程模块和推广活动中。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Water reservoirs provide many societal services in the United States and worldwide including flood control and sources of hydroelectric power, drinking water, and irrigation for agriculture and farming. Despite their vital roles, reservoirs are gradually being filled with sediments as land use and climate change exacerbate soil erosion and sediment transport and deposition in natural and engineered surface water systems. Few suitable sites for new dam construction exist in the United States thereby emphasizing the need for cost-effective management of existing reservoirs. In 2024, the US Army Corps of Engineers (USACE) and the State of Kansas are scheduled to pilot test a novel water-injection dredging (WID) process (an untested but potentially transformative approach) in a federal reservoir in the State of Kansas with the aim of inducing turbidity currents and exporting trapped reservoir sediments to downstream waterways, which could prove crucial for addressing the global concern of reservoir sedimentation and its impact on water security. However, key questions remain regarding the ability of WID to restore reservoir sediment storage capacity, its environmental implications to in-lake water quality, and its downstream effects to channel morphology and aquatic ecosystems. To address these knowledge gaps, the Principal Investigators (PIs) of this project propose to leverage the USACE-Kansas WID field test to collect and analyze sediments, nutrients, and aquatic species count data with the goal of generating fundamental scientific and engineering knowledge on the transport efficacy, mechanisms, and environmental responses following the implementation of WID process in a water reservoir. If WID is shown to be viable, with minimal impact on downstream river ecosystems, the successful completion of this project will benefit society through the generation of new data and fundamental knowledge that could be used in reservoirs around the globe, transforming sediment management, and reducing costs associated with existing dredging techniques. Additional benefits to society will be achieved through student education and training including the mentoring of one undergraduate and one graduate student at the University of Kansas and two undergraduate students and one graduate student at Kansas State University.Existing reservoir sediment management techniques have limited effectiveness because they (1) do not restore natural downstream sediment continuity, (2) require transport, storage, and disposal of dredged materials, and (3) are costly to implement. The basic premise of the water-injection dredging (WID) process is to spray a jet of fluid into the bed of a reservoir, entrain sediments into the overlying water, and initiate a density current (akin to an underwater avalanche) to mobilize stored bed sediments toward the reservoir outlet. While WID has successfully been applied to ports and rivers, it has yet to be tested in a water reservoir thereby raising critical questions regarding its potential efficacy and environmental impact. This project will address these knowledge gaps. The specific objectives of the research are to 1) evaluate the physical mechanisms by which human-induced turbidity currents propagate in reservoirs, using high-frequency turbidity sensing data and computational fluid dynamics modeling; 2) evaluate shifts in reservoir water quality by monitoring thermal stratification and redox conditions using in-situ physicochemical sensors and laboratory experiments before, during, and after the WID field test; 3) assess channel and floodplain accretion rates before, during, and after the WID field test; and 4) continuously assess the response of fish and macroinvertebrate communities to sediment releases and the induced biological, chemical, and physical changes in water quality and habitats throughout the WID demonstration project. The successful completion of this research could transform how reservoirs are managed, potentially extending the usable lifetime of large water storage infrastructure across the globe. To implement the educational and training goals of this project, the Principal Investigators (PIs) will collaborate with the University of Kansas (KU) Self Engineering Leadership Fellows (SELF) program to develop and deliver a workshop for college students to conduct hands-on research with large environmental datasets and develop science communication skills, culminating in a presentation to the State of Kansas and Army Corps of Engineers. In addition, the PIs plan to integrate the findings from this research into relevant course modules and outreach activities at KU and Kansas State University.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.