2018 CSDMS meeting-085: Difference between revisions

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|CSDMS meeting abstract title=How do source-to-sink geomorphic processes mediate flood hazards? Using historical changes to inform predictions
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|CSDMS meeting coauthor first name abstract=Erkan
|CSDMS meeting coauthor last name abstract=Istanbulluoglu
|CSDMS meeting coauthor institute / Organization=University of Washington, CEE
|CSDMS meeting coauthor town-city=Seattle
|CSDMS meeting coauthor country=United States
|State=Washington
|CSDMS meeting coauthor email address=erkani@uw.edu
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|CSDMS meeting coauthor first name abstract=Scott
|CSDMS meeting coauthor last name abstract=Anderson
|CSDMS meeting coauthor institute / Organization=USGS
|CSDMS meeting coauthor town-city=Tacoma
|CSDMS meeting coauthor country=United States
|State=Washington
|CSDMS meeting coauthor email address=swanderson@usgs.gov
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{{CSDMS meeting abstract template 2018
|CSDMS meeting abstract=Flood hazards can increase or decrease as a result of changes in the frequency of high flows and changes in the geometry of river channels, through aggradation, incision, or widening. Across the US, Slater et al. (2015) found that a statistically significant majority of studied sites saw increases in the frequency of flooding over the past several decades. Notably, the magnitude of channel response and hydrologic non-stationarity varied between channels within a region. Here, we focus in on a single region, the Pacific Northwest, and ask 1) can the geomorphic characteristics of a basin explain historical changes in flood hazard? And, 2) how will flood risk change with climate change in relation to source-to-sink sediment dynamics? As a first step in understanding the sensitivity of different basins to future climate change, we look at historical records of both channel geometry change and discharge records at ~60 USGS gage sites across Washington state. We find substantial variation among the studied sites in the magnitude of channel change (quantified in terms of changes in the stage-discharge relationship) over the past 3 decades. Some channels have maintained a steady stage-discharge relationship over 30 years, while others change dramatically on an annual basis. Many, but not all, of these unstable channels drain basins with retreating alpine glaciers. Inspecting the discharge records, we find substantial variation as well, likely driven by the differences in hydrologic regime. In the future, we will use this understanding of historical channel sensitivity to inform our predictive models of both channel geometry change and non-stationarity in high flows.
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Latest revision as of 15:26, 8 May 2018





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How do source-to-sink geomorphic processes mediate flood hazards? Using historical changes to inform predictions

Allison Pfeiffer, University of Washington Seattle Washington, United States. pfeif@uw.edu
Erkan Istanbulluoglu, University of Washington, CEE Seattle Washington, United States. erkani@uw.edu
Scott Anderson, USGS Tacoma Washington, United States. swanderson@usgs.gov


Flood hazards can increase or decrease as a result of changes in the frequency of high flows and changes in the geometry of river channels, through aggradation, incision, or widening. Across the US, Slater et al. (2015) found that a statistically significant majority of studied sites saw increases in the frequency of flooding over the past several decades. Notably, the magnitude of channel response and hydrologic non-stationarity varied between channels within a region. Here, we focus in on a single region, the Pacific Northwest, and ask 1) can the geomorphic characteristics of a basin explain historical changes in flood hazard? And, 2) how will flood risk change with climate change in relation to source-to-sink sediment dynamics? As a first step in understanding the sensitivity of different basins to future climate change, we look at historical records of both channel geometry change and discharge records at ~60 USGS gage sites across Washington state. We find substantial variation among the studied sites in the magnitude of channel change (quantified in terms of changes in the stage-discharge relationship) over the past 3 decades. Some channels have maintained a steady stage-discharge relationship over 30 years, while others change dramatically on an annual basis. Many, but not all, of these unstable channels drain basins with retreating alpine glaciers. Inspecting the discharge records, we find substantial variation as well, likely driven by the differences in hydrologic regime. In the future, we will use this understanding of historical channel sensitivity to inform our predictive models of both channel geometry change and non-stationarity in high flows.