Towards integrated flood management along the lower Rhine and Mississippi Rivers and the international legacy of the 2005 New Orleans Hurricanes Katrina–Rita flood disaster

Figures & data

Figure 1. The cycle of dike management for flood control. The model illustrates the influence of advances in science (e.g. climate change, sea level rise, subsidence, etc.), large flood disasters, and technological advances in engineering.

Table 1. Comparative physical and human indices of lower Mississippi and lower Rhine Rivers.

Indices	Rhine	Mississippi
Drainage basin area (km^2)	185,000	3,210,000
Average discharge (m^3/s)	2150	18,400
Diked floodplain width (km)^a	1.8	10.8
Delta plain area (km^2)	3100^b	36,480
Suspended sediment discharge to coast (tons/yr)	186,000^c	145,000,000^d
Natural areas (%): Alluvial valley^a, delta plain	5, <5^e	35, 60^f
Population	7,200,000^g	2,000,000^h
Main urban areas	Rotterdam, Amsterdam, The Hague, Utrecht, Arnhem, Dordrecht	New Orleans, Baton Rouge, Lafayette
Ranking of port size (2015): # container ships/tonnage^i	Rotterdam: 11/5	South Louisiana: not ranked (<100)/14

^aBetween main flood control dikes along main-stem river valley upstream of delta apex and distributary branches.

^bMiddelkoop and Van Haselen (1999).

^cBased on 6% of incoming suspended sediment loads at the delta apex at Lobith, NL (3,100,000 tons/yr, from Asselman 1999) being discharged into the North Sea (Middelkoop et al. 2010).

^dMeade and Moody (2010).

^eBased on Nienhuis (2008) and Middelkoop and Van Haselen (1999).

^fLower Mississippi River Conservation Committee 2015.

^gLimited to delta; 2012.

^hTwilley et al. (2016).

ⁱ2016 American Association of Port Authorities: World Port Ranking for 2015 Top 100 Ports (http://www.aapa-ports.org/unifying/content.aspx?ItemNumber = 21048), last accessed 5 July 2017.

Table 2. Major elements of IFM adapted to the Rhine delta^a.

Element	Engineering and associated activities	Activities and intended response
Dike adjustment	Move dikes further away from the river	Increase embanked floodplain for floodwater storage, reduce flood stage (reduce area of flood protection)
Sediment management	Dumping sediment in lower channel	Reduce channel incision, channel stabilization
Removal of floodplain obstructions	Re-engineer bridges, remove derelict infrastructure	Increase flood conveyance, reduce flood crests, valuable cultural materials are preserved
Create and enhance side channels	Excavate new channels, restore old channels	Increase floodwater storage, reduce flood crests, enhance riparian, and aquatic ecosystems
Lower embanked floodplain levels	Remove embanked sediment (silt/clay)	Increase floodwater storage, reduce flood crests, enhance riparian wetlands
Reduce height of groynes	Lower groyne structures	Reduce channel roughness, reduce flood crests
Flood bypass channel	Construct pair of dikes to create floodwater channel	Reduce flood stage of IJssel River, functions only during flood stage

^aSource: Silvia et al. (2001), Rijkswaterstaat (2009).

Table 3. Management structure for the Dutch Rhine.

Scale	Key organizations	Roles and responsibilities
International	Int. Commission for the Protection of the Rhine (ICPR)	Regulations between nations on flood protection and water quality and environment
	Central Commission for Navigation on the Rhine (CCNR)	Regulations between nations on navigation, water quality
	European Union	Regulations between nations on water, flood, and environmental protection (esp. Water Framework Directives (2000/60/EC) (EC 2000), Floods Directives (2007/60/EC) (EC 2007))
	Collaborations (non-binding)	Memorandums of agreement concerning the exchange of ideas, personnel, and/or practices related to specific topics
National	Rijkswaterstaat (NL govt.)	Implement international agreements within a national framework; federal laws and guidelines on flood protection and water resources; design, construction, management, and maintenance of flood control infrastructure; water quality; navigation
Regional	Provinces	Implement national plan within provincial framework; land acquisition and modification^a; feedback with national and local entities
Local	^bWater boards	Maintenance and fortification of flood control infrastructure; water distribution and levels; environmental management
	Municipalities	Environmental management; feedback with regional and national entities

^aUntil 2015 this task was the responsibility of Dienst Landelijk Gebied (regional scale).

^bWater boards are considered as local-scale because of being inherently smaller than provinces and for consistency in comparison with Louisiana water boards.

Table 4. Management structure for the lower Mississippi.

Scale	Organization	Roles and responsibilities
International	N/A (binding)
	Collaborations (non-binding)	e.g. Memorandums of agreement concerning the exchange of ideas or practices related to specific topics
National	US Army Corps of Engineers^a	Implement 1928 Mississippi River and Tributaries Project, design flood control infrastructure, operate flood control infrastructure (during floods), data collection, navigation, issue permits for wetland modification
	Federal Emergency Management Agency	Implement federal flood control standards, including Executive Order 13690 (2015): Federal Flood Risk Management Standard
	US Environmental Protection Agency	Enforce section 404c of the Clean Water Act (1972)
	US Fish and Wildlife	Conservation, land and water management within floodplain refuges, Enforce federal Endangered Species Act (1973)
Regional	State	Coordinate with levee boards, conservation, feedback, and exchange between national and local entities (i.e. Louisiana Coastal Protection and Restoration Authority)
Local	Levee boards	Maintenance and monitoring of flood control infrastructure (between floods), land acquisition, drainage projects
	Municipalities	Conservation, feedback with regional and national entities, some maintenance of levees within municipality

^aIncludes the Mississippi River Commission and Mississippi Valley Division.

Figure 2. (A) Lower Mississippi model (U.S. context). The structure and relationship between different governmental scales for flood management along the lower Mississippi in Louisiana. (B) Lower Rhine model (Dutch context). The structure and relationship between different governmental scales for flood management in the Netherlands.

Table 5. Multi-criteria comparison of Louisiana levee boards and Dutch water boards.

Element	Louisiana levee boards		Dutch water boards
	Score	Comments	Score	Comments
Flood control	++	Main priority. Have clear standards and expectations from federal levels (US ACE), coordination with state and municipal entities less clear	+++	Main priority. Have clear standards and expectations from federal levels (Rijkswaterstaat)
Ecosystem	+	Not a formal requirement	++	Formally required as of 2008
Representation	+	Stakeholders not mandated	+++	Stakeholders mandated
Subsidence management	+	Not a priority, although starting to gain some recognition (in New Orleans metro)	+++	High involvement, water-level management over summer/winter explicitly considers subsidence rates
Membership	+	Appointed by governor	+++	Elected from constituencies
Flood basin management (e.g. water levels, other drainage aspects)	+	Drainage, less oriented to managing water body types at a specific water level (elev.)	+++	Sophisticated system of water-level management across the district, often including >100 different water levels
Funding	+	Property tax, leases on local industries, varies annually	+++	Property tax, federal support guaranteed for extended periods
Transparency via world wide web	+	Little information available (e.g. finances, personnel, resources, minutes of meeting)	+++	Information generally available (e.g. personnel, finances, resources, minutes of meetings) in Dutch, and limited in English
Expertise	++	Often contract with consulting companies or with state-level certified engineers (e.g. highway department), much variability in expertise of members	+++	Certified professional staff. Mainly function as an autonomous organization

Note: low (+), moderate (++), high (+++).

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