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Flood BypassesAs A Floodplain Management Technology
University of California Washington – 27 January 2012
G. Mathias Kondolf University of California, Berkeley, and Clarke Scholar, Institute of Water Resources, USACE
Anna Serra LlobetUniversity of California, Berkeley
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Purpose, goals of workshop• Propose a typology of flood bypasses
- advantages/disadvantages - ecological benefits, land requirements
• Review performance of flood bypasses on the - Mississippi River (2011) - Sacramento River
• Consider when most effective, limitations/barriers to implementation
• Develop guidelines for flood bypasses
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9.00 Flood bypasses: what do we mean? Flood bypasses: examples in China, EU & USMatt Kondolf and Anna Serra Llobet
9.15 Bypassing floods on the Sacramento: history and future prospectsKatie Jagt , American RiversDiscussion
10.00 Ecological functions of flood bypasses Todd Strole, TNC St Louis
10.45 Break10.45 Bypasses in the 2011 Mississippi Valley floods: Lessons learned
Scott Whitney, Mississippi Valley DivisionDiscussion
Agenda
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Agenda
11.30 Panel 1. What made the Sacramento/Mississippi bypasses effective? What are limitations/barriers to bypasses in current policy?
Scott Whitney; Shana Udvardy, American Rivers; Pete Rabbon, USACE HQ, (Moderator: Scott Nicholson)
12.00 Lunch
13.00 Panel 2. Can we develop guidelines for when are flood bypasses applicable?
Panel: Sam Riley Medlock, ASFM; Todd Strole; Paul Wagner IWR; Katie Jagt , American Rivers (Moderator: Matt Kondolf)
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Agenda
14.00 Small groups break out to develop guidelines, identify topics for Berkeley graduate student research
15.00 Reconvene, report 15.30 Adjourn
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Flood BypassesWhat do we mean?
G. Mathias Kondolf University of California, Berkeley, and Clarke Scholar, Institute of Water Resources, USACE
Anna Serra LlobetUniversity of California, Berkeley
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Definitions – disappointing?
• “A flood bypass, referred to as a floodway, is created by diversion works and topography that permits excessive amount of water in a river or stream to be directed into a depression that will convey the flood water across land which can tolerate flooding.” (Masoudian, 2009)
Commentary: Definition assumes bypasses must be on low-lying land, would not encompass engineered channels. ‘Floodway’ is typically used in broader sense. Need a better definition.
SOURCES: Mohsen Masoudian (2009). The topographical impact on effectiveness of flood protection measures. Kassel university press GmbH, Kassel.
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Definition
• “The defining characteristic of a bypass is that it routes waters around a constrained reach where consequences of flooding are particularly undesirable” (John Cain)
Among key variables to consider: • Frequency and duration of inundation (dry in non-flood?) • Potential ecological functions • Land use and land costs• Mechanisms for purchase or easement
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Room for the River (The Netherlands)
• The Netherlands Population: 16,783,092 Land below sea level: 25% + 25% more subject to flooding
• Room for the River Current maximum discharge capacity15,000 m3/sec
Discharge capacity on completion16,000 m3/sec
Improve the environmental quality of river areas
“Living With Water” will promote communities that value and adapt to water instead of fearing it
ReasonThe water in the rivers reached extremely high levels in 1993 and 1995. 250,000 people had to be evacuated in 1995
Budget€ 2.3 billion
PlanningStart: 2007Completion: 2015
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Room for the River (The Netherlands)
ObjectiveRoom for the River will reduce high water levels in the Rhine, Meuse, Waal and Ijssel Rivers. By 2015, these rivers will be given more room at 39 locations, using a variety of strategies.
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Room for the River (The Netherlands)
Lowering of floodplains Deepening summer bed Water storage
Dike relocation Lowering groynes High-water channel
Depoldering Removing obstacles Strengthening dikes
SOURCES: Room for the River Project
video
Only in areas in which creating more room for the river is not an option.
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Flood Bypasses: What do we mean?
Levee setback/removed Transitory water storage Flood bypassor overflow basin
SOURCES: Room for the River Project / American Rivers. Alberto Cuadra and Bonnie Berkowitz / The Washington Post. Published on May 8, 2011, 9:59 p.m.
A high-water channel is designed to route overflow away from the river.
Pulling levees inland makes the flood plain wider. Some levees can be removed completely to allow once-reclaimed land to flood.
Some water can be routed to lake beds for temporary storage.
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Flood Bypass vs. Reconnected Floodplain
• Flood bypass (high water channel, flood overflow channel)• Conveys flood waters• Usually implication: separated from the channel
• Transitory storage• On time scale of flood, water does not return to channel
• Reconnected floodplain• Set back levees-floodplain conveyance adjacent to channel
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Flood Bypasses: What do we mean?
Off channel storage
Reconnected floodplain/polder
Reservoir
Upstream
Downstream
Flood bypass
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Flood Bypass systems
Residence timeEcological benefitLand requirements
Bypass tunnel
Guadalupe River (CA, US)
Engineered bypass channel
Waal River (The Netherlands)
Natural channel bypass
Dijle River (Belgium)
Floodplain bypass channel
Yolo Bypass (CA, US)
Reconnected floodplain
Sigma Project(Belgium)
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Flood Bypass systems
Residence timeEcological benefitLand requirements
Bypass tunnel
Guadalupe River (CA, US)
Engineered bypass channel
Waal River (The Netherlands)
Natural channel bypass
Yangtze River(China)
Floodplain bypass channel
Yolo Bypass (CA, US)
Reconnected floodplain
Sigma Project(Belgium)
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Flood Bypasses:some examples in China, Europe and the US
Anna Serra LlobetUniversity of California, Berkeley
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Flood Protection System, Yangtze River
Region: Downstream Three Gorges Dam (China)
River: Yangtze River
Measures: Natural flood bypasses leading to off channel floodplain lakes
Summary: For centuries the Chinese people have been building earthen dykes and diversion works to prevent floods in the Yangtze River. Ironically, the risk of a flood disaster has grown dangerously high.
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Three Gorges Dam
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‘Room for the River Waal’Region: Nijmegen (The Netherlands)
River: Waal
Year: 2013-2016
Practical measures: levee setback
Summary:The dike along the river Waal will be replaced 350 meters land inwards, leaving an island in the middle of the river.
Source: www.floodresiliencity.eu
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The Danube Island Project Region: Vienna (Austria)
River: Danube
Year: 1972
Practical measures: flood bypass channel
Summary: In 1972, an approximately 21 km-long flood bypass canal – the “New Danube” was constructed to direct the water during the floods and used the excavated material to create a flood free island –Danube Island – between the new waterway and the existing river bed.
Source: www.unhabitat.org
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Sigma Plan
Region: East Flanders (Belgium)
River: Schelde
Year: 1997/2005
Practical measures: reconnected floodplain - bypass channel
Summary:The plan contains the following trends:- Heightening of the dikes- to give water more space. The creation of approximately 4000 hectare of free water space in case of a flood.
Source: www.gogkbr.be/index.php?page=wat&hl=en_US
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Yolo bypass Region: Upstream Sacramento Delta (California, US)
River: Sacramento
Year: 1933
Practical measures: Floodplain bypass channel
Summary: During the winter months, weirs in the levee systems release water into the floodway to avoid flooding inhabited areas of the counties.
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Yolo bypasslocation
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Guadalupe River Project
Region: San José (California, US)
River: Guadalupe
Year: 1997-2001
Practical measures: flood bypass tunnel
Summary: A key outcome of the project was to include a double box bypass culvert to help convey flood flows while avoiding and maintaining critical riparian and shaded riverine aquatic habitats.
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Plan view
Guadalupe River Project CollaborativeKey element: Underground bypass box culvert system
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Napa River bypass Region: Napa (California, US)
River: Napa
Year: 2010-2015
Practical measures: flood bypass channel
Summary: Project: The $400 million Napa River/Napa Creek Flood Control Project is lowering dikes, creating floodplains and a bypass, relocating bridges and restoring 900 acres of wetlands according to “living river” principles.
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Bypass
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Flood control bypass channelOverview
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Flood control bypass channelHigh tide
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Flood control bypass channelFlood
Source: www.napavalleyregister.com
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Bird’s Point-New Madrid Floodway
Region: Missouri, US
River: Mississippi
Year: Mississippi River and Tributaries Project, 1928
Practical measures: floodplain bypass Summary: Performed well in the 2011 floods, protecting Cairo, IL.
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Bird’s Point-New Madrid Floodway
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Morganza Spillway
Region: Louisiana, US
River: Mississippi
Year: 1930-1954
Practical measures: floodplain bypass Summary: Its purpose is to divert water from the Mississippi River during major flood events and to help prevent the Mississippi from changing its present course through the major cities of Baton Rouge and New Orleans.
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Bonnet Carré Spillway
Region: St. Charles Parish (Louisiana, US)
River: Mississippi
Year: 1931
Practical measures: Floodplain bypass (delta distributary)
Summary: Is a flood control operation in the Lower Mississippi Valley, which allows floodwaters from the Mississippi River to flow into Lake Pontchartrain and then into the Gulf of Mexico.
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Bypassing floods on the Sacramento: history and future prospects
Katie JagtAmerican Rivers
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Ecological functions of flood bypasses
Todd StroleTNC St Louis
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Bypasses in the 2011 Mississippi Valley floods: Lessons learned
Scott WhitneyMississippi Valley Division
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Panel 1.What made the Sacramento/Mississippi bypasses effective? What are limitations/barriers to bypasses in current policy?
Moderator: Scott Nicholson
Scott Whitney; Shana Udvardy, American Rivers; Dave Wegner, Water & Power Subcommittee, House T&I Committee; Pete Rabbon, USACE HQ
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Panel 2.Can we develop guidelines for when are flood bypasses applicable?
Moderator: Matt KondolfSam Riley Medlock, ASFM; Todd Strole, TNC St Louis; Paul Wagner, IWR
• Taking a systems perspective, when is this technology applicable: environmental context, socio-economic context, and at what scale in the landscape?
• How can this technology support sustainable growth and resilience?
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Small groups break out to develop guidelines, identify topics for Berkeley graduate student research-Reconvene, report
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Next meeting
“Wise-Use of Floodplains: Adaptation in America and Europe”
Workshop Fri-Sun 9-10 March 2012 University of California, Berkeley