HWRS 695 Colloquium Weekly Talks in April

April 15: The Catalina-Jemez Critical Zone Observatory (CZO) down deep: Evolution by jerks?

Speaker: Dr. Jon Chorover, UA Professor and Department Head, Department of Soil, Water, and Environmental Science, School of Natural Resources and the Environment, and Joint Professor, Department of Hydrology and Water Resources, School of Earth and Environmental Sciences.

One hypothesis being tested at the Catalina-Jemez CZO is that the critical zone evolves structure that enables energy dissipation during short-term hydrologic episodes, including pulsed throughputs from surface soils to deeper subsurface stores of water and reduced carbon. Several lines of evidence from the Catalina-Jemez CZO indicating the importance of deep subsurface hydrologic flows on (bio)geochemical processes will be discussed. Experimental approaches to quantify subsurface couplings of hydrology, biogeochemistry, and microbial ecology in weathered bedrock will be discussed. More info…

April 22: The emerging field of hydrogeodesy

SpeakerDr. James Famiglietti, Professor of Earth System Science & Civil and Environmental Engineering, University of California-Irvine; Director, UC Center for Hydrologic Modeling; Research Scientist, Jet Propulsion Laboratory; and UA HWRS Alumnus. More info…

April 29, 2015: Hydrology of desert rivers: Expectations for change

SpeakerDr. Thomas Meixner, Professor, Associate Department Head, and Director of Graduate Studies, HWRS

The river basins of the Basin and Range basin face profound changes in climate, land use and hydrology over the next several decades.  The combined changes in the physical forcing of riparian ecosystems may induce profound changes in the biological and geomorphic services that society derives from riparian ecosystems.  Recent climate simulations demonstrate that winter precipitation is likely to decline across southern Arizona, the trend for summer rain is more uncertain, and the duration and intensity of droughts might increase while extreme rain events (e.g. the 10 year storm) will likely become more intense.

The changes in climate forcing when combined with projected population growth will likely result in river systems that are less perennial but also more frequently scoured out by geomorphically significant storm flows.  This combination of drier mean conditions but more extreme flood events will likely have specific effects on riparian ecological communities which will result in significant geomorphic change in these riparian systems.  In particular, more frequent floods capable of scouring vegetation will likely result in a more diverse plant community than if floods were less frequent.  However, there will likely be a loss of wetland species and charismatic mega-flora, such as Populus fremontii, from the currently perennial river systems that will become intermittent to ephemeral in the future.  Additionally, these vegetative changes will probably reduce the riparian systems ability to resist geomorphic evulsions and thus have significant implications for the communities near the banks of these rivers. More info…

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