CAREER: Land Use, Geologic and Climatic Controls on Stream Processes in Northern New England Using Airborne Laser Swath Mapping

Boston College, Chestnut Hill MA

Investigators

Abstract

This project integrates analysis of remote-sensing data, field surveys and mapping, and fluvial models to test hypotheses of the fundamental controls on stream form and process in the deglaciated landscape of northern New England. Rivers in regions covered by late Pleistocene continental glaciers evolve through a combination of bedrock erosion, availability and transport of bedload, and ecological succession. Stream morphology, and therefore habitat suitability, varies in the downstream direction, depending on local sedimentary sources and sinks. Historical land-use change from deforestation to riparian protection further influences fluvial processes. At present, motivated by the near extirpation of Atlantic salmon in Maine, non-profit groups and government agencies are working to reverse fluvial habitat degradation by stabilizing watershed sediment inputs and removing dams. However, these restoration efforts are typically guided by geomorphic studies of salmon rivers in other regions. This proposal seeks to understand the trajectory of landscape response to changes in land use, and develop and test spatial numerical models that relate stream physical processes to habitat quality. Airborne laser swath mapping (ALSM) will expand the advances made in quantitative geomorphology using digital elevation models (DEMs) over the past 15 years. ALSM surveys yield high-resolution measurements of "bare-earth" topography, thickness of forest cover, and water depth over entire watersheds. This study will collect ALSM data from three watersheds in Maine and use channel morphologic measurements as input for numerical models of transport processes. These spatial models will be tested through comparison to field surveys, geological and ecological mapping, fish-population datasets, and past conditions using historical aerial photographs. Teams of undergraduate and Master's students will conduct the research, working together on each of the watersheds using field, geospatial, and numerical methods. Each student will have a role within the team that evolves to eventual production and presentation of research projects. Multi-year student involvement will ensure strong professor-student, graduate-undergraduate, and undergraduate-undergraduate mentoring. The proposed research is directly relevant to ongoing ecosystem restoration projects in northern New England. All phases of this study will include direct outreach by students and the PI to share results and methods with land managers, watershed restoration non-profit groups, high school students, and other scientists from a variety of fields in forums from field workshops to national meetings. These efforts will include specific recommendations, based on research findings, for optimizing future restoration projects. Through interactions with community-based groups, students will gain an appreciation for the challenges of land-management decision-making processes. This exchange between students and stakeholders will ensure that the research has a strong societal and scientific impact.