Flood Bypasses As A Floodplain Management Technology University of California Washington – 27...

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

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

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

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)

Agenda

14.00 Small groups break out to develop guidelines, identify topics for Berkeley graduate student research

15.00 Reconvene, report 15.30 Adjourn

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

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.

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

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

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.

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.

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.

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

Flood Bypasses: What do we mean?

Off channel storage

Reconnected floodplain/polder

Reservoir

Upstream

Downstream

Flood bypass

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)

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)

Flood Bypasses:some examples in China, Europe and the US

Anna Serra LlobetUniversity of California, Berkeley

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.

Three Gorges Dam

‘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

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

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

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.

Yolo bypasslocation

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.

Plan view

Guadalupe River Project CollaborativeKey element: Underground bypass box culvert system

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.

Bypass

Flood control bypass channelOverview

Flood control bypass channelHigh tide

Flood control bypass channelFlood

Source: www.napavalleyregister.com

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.

Bird’s Point-New Madrid Floodway

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.

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.

Bypassing floods on the Sacramento: history and future prospects

Katie JagtAmerican Rivers

Ecological functions of flood bypasses

Todd StroleTNC St Louis

Bypasses in the 2011 Mississippi Valley floods: Lessons learned

Scott WhitneyMississippi Valley Division

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

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?

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

Next meeting

“Wise-Use of Floodplains: Adaptation in America and Europe”

Workshop Fri-Sun 9-10 March 2012 University of California, Berkeley

Thank you!

G. Mathias Kondolf kondolf@berkeley.edu

Anna Serra Llobet annaserrallobet@berkeley.edu