NSF Award
2500251
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.<br/><br/>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.<br/><br/>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.
