Collaborative Research: Interactions between Holocene Lake Levels and Alluvial Fans in the Western U.S. in Response to Changing Climates

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The primary goal of this project is to develop an integrated record of late Holocene hydrologic change and landscape response in the western U.S. to understand the effects of recent climate changes on landscape processes, thereby providing an analog for what may happen in the future under different climate scenarios. This will be accomplished by integrating late Holocene lake-level records of four different basins with their surrounding alluvial fan records along a 450 km north-south transect in the western Great Basin. Raised shorelines surrounding Pyramid and Winnemucca lakes, Walker Lake, and Owens Lake reflect significant fluctuations in the water balance of the region and form excellent time markers that can be used to establish the timing, spatial distribution, and types of floods on alluvial fans across broad areas. These records will be augmented by additional age dating of shorelines and fans to further understand how each lake basin responded to subtle late Holocene climate fluctuations, both in terms of their water balance and the types and frequencies of floods caused by altered climate regimes.The broader impacts of this research range from educational activities and broad dissemination of results to geologic hazard assessment. The science of delineating flood hazards on alluvial fans is relatively immature compared to assessing hazards associated with river floods. This project will provide critical information on alluvial fan flooding to practitioners of hazard assessments by documenting the timing, frequency, style, spatial extent, and causes of young alluvial fan activity across large areas. The project will utilize a diverse set of tools including geologic mapping, geomorphology, sedimentology, stratigraphy, geochronology, tephrochronology, remote sensing, and paleoclimate analysis to develop a regional synthesis of hydrologic variability and alluvial fan activity across a broad N-S swath of the western U.S. The interdisciplinary nature of this project lends itself to teaching students a variety of skill sets used by Quaternary geologists and will contribute to the education of two graduate students, as well as undergraduate research assistants involved in the project and about 15-20 other students who will enroll in a course based on this research at University of Nevada, Reno. Results will be presented at two or more professional meetings and published in at least two peer-reviewed journal articles. To reach a broader audience, results will also be used to develop an educational module on the effects of climate change on the landscape that will be featured on the Great Basin Paleoenvironmental Database (GBPED) web site (http://www.dri.edu/gbped). The GBPED is a publicly accessible resource viewable in Google earth that provides abstracts of scientific papers on all aspects of environmental change along with place marks that show where the studies were conducted.