ABSTRACT



River ecosystems have been severely degraded over recent decades by human activities such as the construction of dams, fertilizer applications from agriculture, and urbanization, to name but a few. This degradation includes both physical, i.e., geomorphic, and ecological changes. Assessing the results of and potential solutions to these problems necessitates understanding not only geomorphic, ecological, and biogeochemical processes, but more importantly, how these processes interact. This project will use flume, field, and numerical modeling experiments to develop a quantitative and mechanistic understanding of how fluvial geomorphic forms and processes influence ecosystem function, namely stream nutrient retention. Outdoor experimental flumes will be constructed to examine the role of in-channel versus hyporheic transient storage in nutrient retention, and how various geomorphic parameters control these storage zones, as well as how fluvial geomorphic forms influence the rates of biochemical retention of nutrients. The research will then be extended to field-scale channel manipulations, which will include both manipulations of flow conditions in natural river channels, as well as the more substantial manipulation of river restoration projects. Using the insight gained from the flume and experimental manipulation studies, the second phase of the project will develop the initial components of a Stream Ecosystem Model, coupling existing geomorphic and ecological models in order to examine how geomorphic forms and processes and ecological processes interact across a range of spatial and temporal scales. This model will be uniquely usable to explore and develop theoretical questions. Beyond research, this project will develop a series of educational programs to expose students, grades 7-12, to spatial and quantitative aspects of environmental science, particularly river studies. The education program will leverage off of an existing environmental field education program and an existing general science education outreach program for middle school students, thus providing a more holistic environmental educational experience for middle school and high school students. The education program will use pre-service teachers, providing an immediate source of future environmental educators with substantial spatial environmental analysis education experience.

This research is inspired by the realities of widespread physical and ecological disturbance to rivers and streams along with the increased research and application of river restoration. This project will use a series of experimental stream manipulations and numerical modeling to develop fundamental scientific knowledge of the way physical and biological processes in streams are inter-twined. This knowledge is critical to developing a holistic understanding of stream ecosystems as such understanding is the basis for effective management and potential restoration of freshwater resources. The research during this project will also serve as the basis for a series of educational courses designed to teach students how physical and biological processes in rivers are linked, and these courses will span from graduate-level seminars to short courses for middle-school students.

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