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2020 Darcy Lecture

Reed Maxwell, Ph.D.

Reed Maxwell, Ph.D., is a professor in the Department of Civil and Environmental Engineering (CEE) and the Princeton Environmental Institute (PEI) at Princeton University. He also directs the Integrated GroundWater Modeling Center. His research interests are focused on understanding connections within the hydrologic cycle and how they relate to water quantity and quality under anthropogenic stresses.

Maxwell is an elected Fellow of the American Geophysical Union, was the 2018 Boussinesq Lecturer, and the 2017 School of Mines Research Award recipient. He has authored more than 140 peer-reviewed journal articles and teaches classes on integrated hydrology, fluid mechanics, and modeling terrestrial water flow.

At Princeton, Maxwell currently leads a research group of graduate students, postdoctoral researchers, and staff housed within CEE and PEI. Over his career, he has collaborated with, and mentored more than, 14 Ph.D. students and 20 M.S. thesis students. Prior to coming to Princeton, Maxwell was faculty at the Colorado School of Mines and a postdoc and then staff in the hydrologic sciences group at Lawrence Livermore National Laboratory.

Maxwell received his Ph.D. degree in environmental water resources from the Civil and Environmental Engineering Department at the University of California, Berkeley.

The request period to host the 2020 Darcy Lecture is now closed. Requests to host the 2021 lecture series will be accepted in the fall of 2020.

Maxwell Will Offer a One of the Following Three Lectures at Participating Venues in 2020

Lecture 1

“Hydrology from the bottom up: how groundwater shapes the water cycle”

Groundwater is one of Earth’s largest freshwater stores, yet it is often out of sight and out of mind. While groundwater is often conceptualized as a separate store from surface water, feedbacks between groundwater depth, soil moisture, streamflow, and plant water usage become increasingly important for characterizing the water and energy drivers of watershed fluxes. Thus, the literature shows that groundwater is intimately linked not only to surface water, but also the land surface, and the lower atmosphere. This lecture will explore the linkages between groundwater and the rest of the hydrologic cycle. It will discuss some fundamental relationships that describe groundwater’s interconnections with land surface fluxes and how recent advances in our understanding these feedbacks can help us more holistically manage our watersheds. The growing body of evidence demonstrating the critical role of groundwater-surface water interactions has driven a new wave in groundwater hydrology. As we increasingly understand groundwater connections and learn how critical groundwater interactions are water-resource challenges, groundwater becomes a central part of integrated analyses that previously have been considered across disciplinary boundaries.

Lecture 2

"Hydrology in the supercomputing age: How computational advances have revolutionized our field, and what big data and massively parallel simulations mean for the future of hydrologic discovery"

We are in the midst of a revolution in computing and data. In the past 50 years we have moved from electrical analog models to massively parallel computer systems. The fastest computers in the world when landmark papers such as Freeze and Harlan were written are much slower than the average smartphone of today. Hydrology is taking advantage of this revolution in many ways. Computational Hydrology seeks to leverage modern computing capacity to study water and energy fluxes and stores across the hydrologic cycle at spatial scales and complexity not previously possible. Integrated hydrologic simulations that couple boundary layer, vegetation, and land energy processes with surface and subsurface hydrology have great potential to advance our understanding of terrestrial hydrology spanning small catchments to the continental scale. Several movements within hydrology, such as the so-called hyperresolution approach, have organized and accelerated this goal. Hydrologic simulation from a historical perspective, starting with the early watershed models to more modern, integrated approaches that realize blueprints laid out fifty years ago will be presented. The lecture will discuss how computational advances are shaping our simulation capabilities, changing the questions that we are able to ask as scientist, and changing how we educate our students. High-resolution, continental-scale simulation is an exciting component of computational hydrology forecasting and scientific discovery. It will outline a path to move beyond our traditional siloed simulation platforms and to leverage these large datasets and massive community development investments to better connect our hydrologic models to the communities outside of hydrology.

Lecture 3

"Killer beetles, naked trees and dirty water: Understanding hydrology and water quality impacts from the Mountain Pine Beetle infestation in the Rocky Mountain west"

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.

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