HR: 09:00h
AN: NB21G-03    [Abstracts]
TI: A Conceptual Model for Floodplains in California's Central Valley and a Method for Identifying Representative Floods and Floodplains
AU: * Opperman, J J
EM: jjopperman@ucdavis.edu
AF: Center for Integrated Watershed Science and Management, University of California, Davis, CA 95616 United States
AU: Andrews, E
EM: e.andrews@pwa-ltd.com
AF: Philip Williams and Associates, 720 California Street Suite 600, San Francisco, CA 94108 United States
AU: Bozkurt, S
EM: s.bozkurt@pwa-ltd.com
AF: Philip Williams and Associates, 720 California Street Suite 600, San Francisco, CA 94108 United States
AU: Mount, J F
EM: jfmount@ucdavis.edu
AF: Center for Integrated Watershed Science and Management, University of California, Davis, CA 95616 United States
AU: Moyle, P B
EM: pbmoyle@ucdavis.edu
AF: Center for Integrated Watershed Science and Management, University of California, Davis, CA 95616 United States
AB: Currently, significant resources are being invested in restoring native species and ecosystems in California's Central Valley and the Sacramento-San Joaquin Delta, led by the California Bay-Delta Authority (CBDA). Functioning floodplains provide numerous ecological benefits and floodplain restoration is emerging as important component of ecosystem restoration in this region. We developed a conceptual model that describes the linkages between physical (hydrologic and geomorphic) processes and ecosystem processes and responses on Central Valley floodplains. Central to this model is the role of hydrological variability in driving topographic diversity, ecosystem heterogeneity and ecological processes. We attempt to capture the extremely complex linkages between hydrological variability and ecosystem response through `representative floods.' A representative flood encompasses a set of hydrological variables, such as frequency and duration, which produce a characteristic suite of ecological benefits. For example, frequent, long duration flooding in the spring provides spawning and rearing habitat for native fish and promotes high phytoplankton productivity which can be exported to riverine and delta ecosystems. Less frequent, higher magnitude floods drive extensive geomorphic change upon the floodplain, creating topographic and, ultimately, ecological heterogeneity. Here we describe a process to define, map, and quantify the area inundated by a particular representative flood in the Sacramento River valley. To illustrate we identify the area inundated by a frequent (exceedance probability of 67%), long duration (> 7 days) flood that occurs in the spring. We used paired gauges to find the stage corresponding to the representative flood parameters and compared a plane connecting the gauges to topography in the intervening reach of river. We found that this type of representative flood inundates very little area in the Sacramento Valley; primary areas of inundation are within the Yolo Bypass, an engineered floodplain that flanks the Sacramento River. This analysis can be used to identify areas of floodplain that potentially provide the ecological benefits described in the conceptual model and can guide restoration programs seeking to increase these benefits.
DE: 1821 Floods
DE: 1824 Geomorphology (1625)
DE: 1890 Wetlands
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly