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Flood Bypasses As A Floodplain Management Technology University of California Washington – 27 January 2012 G. Mathias Kondolf University of California,

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Presentation on theme: "Flood Bypasses As A Floodplain Management Technology University of California Washington – 27 January 2012 G. Mathias Kondolf University of California,"— Presentation transcript:

1 Flood Bypasses As 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 Llobet University of California, Berkeley

2 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

3 9.00Flood bypasses: what do we mean? Flood bypasses: examples in China, EU & US Matt Kondolf and Anna Serra Llobet 9.15Bypassing floods on the Sacramento: history and future prospects Katie Jagt, American Rivers Discussion 10.00Ecological functions of flood bypasses Todd Strole, TNC St Louis 10.45Break 10.45Bypasses in the 2011 Mississippi Valley floods: Lessons learned Scott Whitney, Mississippi Valley Division Discussion Agenda

4 11.30Panel 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) 12.00Lunch 13.00Panel 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)

5 Agenda Small groups break out to develop guidelines, identify topics for Berkeley graduate student research 15.00Reconvene, report 15.30Adjourn

6 Flood Bypasses What do we mean? G. Mathias Kondolf University of California, Berkeley, and Clarke Scholar, Institute of Water Resources, USACE Anna Serra Llobet University of California, Berkeley

7 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.

8 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

9 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 capacity 15,000 m 3 /sec Discharge capacity on completion 16,000 m 3 /sec Improve the environmental quality of river areas “Living With Water” will promote communities that value and adapt to water instead of fearing it Reason The water in the rivers reached extremely high levels in 1993 and ,000 people had to be evacuated in 1995 Budget € 2.3 billion Planning Start: 2007 Completion: 2015

10 Room for the River (The Netherlands) Objective Room 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.

11 Room for the River (The Netherlands) Lowering of floodplainsDeepening summer bedWater storage Dike relocationLowering groynesHigh-water channel DepolderingRemoving obstaclesStrengthening dikes SOURCES: Room for the River Project video Only in areas in which creating more room for the river is not an option.

12 Flood Bypasses : What do we mean? Levee setback/removedTransitory water storageFlood bypass or 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.

13 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

14 Flood Bypasses: What do we mean? Off channel storage Reconnected floodplain/polder Reservoir Upstream Downstream Flood bypass

15 Flood Bypass systems Residence time Ecological benefit Land 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)

16 Flood Bypass systems Residence time Ecological benefit Land 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)

17 Flood Bypasses: some examples in China, Europe and the US Anna Serra Llobet University of California, Berkeley

18 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.

19 Three Gorges Dam

20 ‘Room for the River Waal’ Region: Nijmegen (The Netherlands) River: Waal Year: 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:

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22 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:

23 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:

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25 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.

26 Yolo bypass location

27 Guadalupe River Project Region: San José (California, US) River: Guadalupe Year: 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.

28 Plan view Guadalupe River Project Collaborative Key element: Underground bypass box culvert system

29 Napa River bypass Region: Napa (California, US) River: Napa Year: 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.

30 Bypass

31 Flood control bypass channel Overview

32 Flood control bypass channel High tide

33 Flood control bypass channel Flood Source:

34 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.

35 Bird’s Point-New Madrid Floodway

36 Morganza Spillway Region: Louisiana, US River: Mississippi Year: 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.

37 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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39 Bypassing floods on the Sacramento: history and future prospects Katie Jagt American Rivers

40 Ecological functions of flood bypasses Todd Strole TNC St Louis

41 Bypasses in the 2011 Mississippi Valley floods: Lessons learned Scott Whitney Mississippi Valley Division

42 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

43 Panel 2. Can we develop guidelines for when are flood bypasses applicable? Moderator: Matt Kondolf Sam 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?

44 Small groups break out to develop guidelines, identify topics for Berkeley graduate student research - Reconvene, report

45 Next meeting “Wise-Use of Floodplains: Adaptation in America and Europe” Workshop Fri-Sun 9-10 March 2012 University of California, Berkeley

46 Thank you! G. Mathias Kondolf Anna Serra Llobet


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