Special Seminar: Jason Gurdak
The out-of-sight Global Water Crisis: A Vision Toward a Sustainable Groundwater Future
As the world’s largest store of readily accessible freshwater, groundwater helps sustain ecosystems, provides a strategic reserve during drought, and enables human adaptation to climate variability and change. Despite its critical importance, groundwater is often poorly understood and inadequately managed relative to the more visible surface water. The largely hidden nature of groundwater has translated into resource development that is often uncontrolled and not incorporated into watershed management. As a consequence, most of the world’s major aquifers in semi-arid and arid regions are experiencing rapid and unprecedented rates of groundwater depletion. Future climate variability and change may intensify groundwater depletion, which will have profound social and economic consequences related to declines in agricultural productivity and energy production, potential damage to transportation and urban infrastructure from land subsidence, loss of critical ecosystems in groundwater-dependent streams and wetlands, and increased seawater intrusion in coastal aquifers.
This presentation explores an innovative research vision to help manage our way through the global groundwater crisis. Recent findings from the UNESCO-IHP groundwater and climate change program (GRAPHIC) will be presented. GRAPHIC is the only global scale research, education, and outreach program that addresses the global groundwater crisis and climate variability and change. Particular focus will be on climate change impact studies that diagnose the important vadose zone processes and land-management practices that control recharge, both historically and under projected 21st century climate. Additional new insight will be presented about the process-level controls of interannual to multidecadal climate variability on transient recharge rates in the U.S. Principal Aquifers, including the High Plains aquifer in Colorado. This insight will help design a new type of distributed managed aquifer recharge (MAR) system that captures stormwater, enhances recharge, increases groundwater storage, and provides a promising adaptation strategy to conjunctively manage surface and groundwater resources under projected increased hydrologic variability. Finally, the presentation will explore the importance of framing the groundwater crisis within the water-energy-food nexus, which is the most fundamental environmental issue facing the world today. Innovative science and engineering needed to drive the successful management of the global groundwater crisis will come from collaborative and multidisciplinary team of researchers that spans the fields of hydrology, geology, engineering, climate, ecology, economics, law, and policy, while also engaging local resource managers and stakeholders.
Dr. Jason Gurdak is an Assistant Professor in the Department of Earth & Climate Sciences at San Francisco State University (SFSU) and Coordinator of the United Nations Education, Scientific, and Cultural Organization (UNESCO) sponsored research program that addresses climate variability and change and the global groundwater crisis. Prior to joining SFSU, he was a Hydrologist for 10 years with the U.S. Geological Survey Colorado Water Science Center in Lakewood, Colorado. He has degrees from Colorado School of Mines (PhD, Geology and Geological Engineering: Geochemistry; MS, Environmental Science and Engineering) and Bates College (BS, Geology). He has authored more than 30 publications on a range of topics in hydrology. His current research advances understanding of mechanisms that link climate variability on interannual to multidecadal timescales and hydrologic variability that has important implications for successfully managing water resources in Colorado and across the U.S.
Analytical Chemistry Seminar: Melissa Ugelow
Jointly sponsored by the Department of Chemistry and Biochemistry, CIRES, and the Environmental Program
Optical Properties of Titan Haze Analogs Using Photoacoustic and Cavity Ring-Down Spectroscopy
Melissa S. Ugelow 3rd Year Graduate Student
The organic haze that surrounds Saturn's moon Titan is formed through the photolysis and electron initiated dissociation of methane and nitrogen. Both the chemical pathways leading to the haze formation and the resulting haze optical properties are still highly uncertain. Here we examine the optical properties of simulated haze aerosol to better understand its scattering and absorption properties, and the impact of haze on Titan's radiative balance. To determine the complex refractive index of haze particles, we combine two spectroscopic techniques, one that measures absorption and one that measures extinction: photoacoustic spectroscopy coupled with cavity ring-down spectroscopy (PASCaRD). This technique provides the benefit of a high precision determination of the imaginary component of the refractive index (k), along with the highly sensitive determination of the real component of the refractive index (n) in a flow system set up. The Titan aerosol analogs studied are produced by two energy sources, UV excitation and spark discharge excitation. The refractive indices are determined at two wavelengths, 405 and 532 nm, using the PASCaRD system. I will present preliminary data on the complex refractive indices of laboratory generated Titan aerosol analogs at both wavelengths using both energy sources. The high precision values determined from this method should be useful for modelers and for data retrieval from spacecraft and remote sensing instruments.