Events Calendar

USC Water Institute Seminar

Speaker: Thomas C. Harmon, University of California, Merced & UCLA Center for Embedded Networked Sensing (CENS)

Talk Title: Whole Stream Metabolism as a Beacon for Change in Aquatic Ecosystems: Results from a Study of the Human-Dominated River Basin

Abstract: Metabolism estimates (gross primary production, GPP and community respiration, CR), based on the continuous monitoring of flow and water properties (primarily dissolved oxygen, temperature), can provide an integrative assessment of the effects of various disturbances on aquatic ecosystem function. The long-term goal of this work is to learn how to relate GPP/CR responses in lotic ecosystems to natural and anthropogenic disturbances, such as short- or long-term reservoir operational changes for drought management, flood control, fish habitat enhancement, or salinity and nutrient discharges due to land management practices. This presentation highlights observations from a GPP/CR observational network embedded in the human-dominated San Joaquin River Basin (SJRB) including reaches of the SJR and the Lower Merced River, located in the Central Valley of California. The network enables spatial (both longitudinal and transverse gradients) and temporal (daily, seasonal and interannual) variation of these metabolism estimates. The observational network will be described in terms of: (1) design and installation of a reproducible infrastructure of GPP/CR observational nodes, (2) analysis aimed linking the spatiotemporal metabolic trends to natural factors such as the seasonal radiation availability or nutrient input from leaf decay, and (3) separating natural effects from the ones triggered by human disturbances in order to better inform water resources management decisions. For example, observations over the 2009-10 water year, demonstrate that the Lower Merced River behaves as a heterotrophic system, with significant human-triggered temporal changes in metabolism clearly observable by the monitoring network. For example, the GPP/CR ratio decreased from 0.6 to 0.2 as a consequence of a large flow disturbance associated with short-term reservoir releases mandated biannually to support salmon migration. This and other examples set at different temporal and spatial scales will be presented and discussed in terms of management implications.



Biography: Tom Harmon is Professor and Chair of the School of Engineering and Founding Faculty member at the University of California, Merced. He is also affiliated with the Sierra Nevada Research Institute. He directs contaminant transport observation and management research for the UCLA Center for Embedded Networked Sensing (CENS), and maintains an adjunct position in the UCLA Department of Civil & Environmental Engineering. Professor Harmon earned a B.S. in Civil Engineering from the Johns Hopkins University, and M.S. and Ph.D. degrees in Environmental Engineering from Stanford University. As an environmental engineer, his teaching and research focuses on a variety of topics pertaining to understanding and solving soil, groundwater, and surface water problems in natural and engineered environmental systems.

Host: Prof. Gaurav Sukhatme

Audiences: Everyone Is Invited

Contact: Kanak Agrawal