Warmer temperatures and drought conditions exacerbated by climate change have intensified mountain pine beetle (MPB) infestation in the Rocky Mountains of North America. The associated tree death over the last decade is unprecedented in recorded history; more than four million acres of forest in Colorado and Wyoming have been impacted by MPB. The visual impact of dying and dead forests is stunning, but the invisible changes to the water cycle may be a longer-lasting legacy. From 1998 to 2014, MPB infestation extended to vital watersheds in the Rocky Mountain west. This included the Platte and Colorado River headwaters, which provide water for 30 million residential users and 1.8 million acres of irrigated agriculture. This lecture will present research from a six-year project that brought together hydrologists, environmental engineers, social scientists and education and outreach specialists to study the broad water quality, quantity and social impacts of the MPB epidemic. Several science paradoxes emerged in this work around issues of scale. For example, hydrologic changes from the tree-to-hillslope scale are clearly documented while these same processes appear to reverse as we move to the catchment-to-regional scale. Increases in dissolved organic carbon are creating water quality challenges for local producers, yet water quantity impacts are inconclusive. This work builds process understanding with local-scale observations and uses hydrologic models to bridge across scales. These models demonstrate how competing factors may buffer hydrologic response to tree mortality from hillslope to watershed scales. Furthermore, we found persistent shifts in watershed behavior as flow paths are altered by a changing landscape. Ultimately, our work to identify changes in stream water sources in MPB-infested watersheds provides insights into the future behavior of forested landscapes that are changing throughout the region and worldwide.
Dr. Reed Maxwell is a faculty member in the Geology and Geological Engineering Department, a core faculty member in the Hydrologic Science and Engineering Program, and the Director of the Integrated GroundWater Modeling Center (IGWMC) at the Colorado School of Mines. His research interests are focused on understanding connections within the hydrologic cycle and how they relate to water quantity and quality under anthropogenic stresses. He is an elected Fellow of the American Geophysical Union, was the 2018 Boussinesq Lecture and the 2017 School of Mines Research Award recipient. He has authored more than 120 peer-reviewed journal articles and teaches classes on integrated hydrology, fluid mechanics and modeling terrestrial water flow. He currently leads a research group of graduate students, postdoctoral researchers and staff housed in the IGWMC at Mines. He has graduated 13 PhD students and 20 MS thesis students since coming to Mines in 2009. Before joining the faculty at Mines, Dr. Maxwell was a postdoc and then staff in the Hydrologic Sciences group at Lawrence Livermore National Laboratory and he holds a Ph.D. degree in Environmental Water Resources from the Civil and Environmental Engineering Department at the University of California, Berkeley.