Hydrologic Extremes and Their Impact on Water Quality

Abstract

Extreme hydrologic events, such as floods and droughts, are becoming ever more common as hydrometeorological drivers shift in response to a changing climate. In the first part of this talk, we outline how climate change affects extreme events in both water quantity and quality, specifically floods, droughts, and extreme water temperatures. In the second part of this talk, we will discuss the effects of such extreme events on water quality. Our capacity to monitor and predict the effects of hydrologic extremes on water quality is closely tied to the resolution of our observational datasets. While many countries are or have invested in extensive, automated and real-time river gauging networks, the associated infrastructure dedicated to monitor the chemistry of these waters is often much coarser and commonly focused on a specific compound or class of interest. Now, a new generation of high frequency monitoring capabilities are allowing development of a comprehensive suite of major solute geochemistry in rivers at unprecedented temporal resolution. Here we will describe the operation of the first and only ‘RiverLab’ facility deployed in North America. This lab-in-the-field technology has produced three years of major ion chemistry in a large agricultural watershed at 30-minute frequency, revealing the disproportionate effect of storms as sources of error in load estimates. The same facility has now been used to document a prolonged period of drought, revealing the capacity for substantial secondary carbonate precipitation and an impediment to lateral carbon transport at continental scales.

Bios

Manuela Brunner is a tenure-track assistant professor at the Institute for Atmospheric and Climate Science at ETH Zurich and the WSL Institute for Snow and Avalanche Research SLF in Davos. Before moving to Davos, she studied Geography and Climate Sciences at the University of Bern, obtained a PhD from the Universities of Zurich and Grenoble-Alpes, and did postdocs at the Swiss Federal Institute for Forest, Snow and Landscape Research WSL and the National Center for Atmospheric Research in Boulder Colorado. Her research focuses on extreme climatic and hydrological events such as floods and droughts. She studies the hydro-meteorological drivers of extreme events, develops methods for their prediction, and assesses changes in the water cycle and extremes. Her group at ETH and SLF quantifies the hazard potential and water availability in mountain regions under global change.

Jenny Druhan is an Associate Professor at the University of Illinois Urbana Champaign Department of Earth Science & Environmental Change. She is also a Chercheure Associée (Research Associate) at the Institut de Physique du Globe de Paris. She holds a B.S. from the University of North Carolina, an M.S. from the University of Arizona Department of Hydrology and Water Resources, and a Ph.D. from the University of Berkeley Department of Earth & Planetary Science. Her work centers on application of reactive transport principals to a variety of Earth systems. Most recently she has focused on the structure and function of the Critical Zone, developing new modeling frameworks which merge the distribution of fluid ages and transit times through watersheds with the chemical reactions that set river chemistry and enable geogenic nutrient availability for ecosystems.