Changes in the Discharge of Suspended Sediment along the Missouri-Mississippi River System, VIII ENES, Campo Grande, Brasil 6 November 2008 John Moody and Bob Meade

Introduction Bob Meade John Moody

Motivation: New Orleans after Hurricane Katrina Photos: Smiley N. Pool and Michael Amsworth, WWLTV

Because deposition constructs barrier islands and wetlands that are protection for New Orleans Remember that sediment deposition can be good

Some Candeleur islands before Katrina Two days after Katrina

Summary of talk 1.Virtual tour a.Landscapes along the Missouri and Mississippi b.Engineering activities along the Missouri and Mississippi River System 2.The mystery of the missing sediment

Rainbow Great Falls of the Missouri River River Horseshoe Black Eagle Note: water has little sediment Montana

Photo by Bob Lindholm Airphoto-Jim Wark Missouri Breaks Montana Note: water has little sediment

Missouri Breaks McClelland Ferry Montana Note: water has little sediment

Fort Peck Dam View: upriver Montana

Confluence below Fork Peck Dam Rio Milk Rio Missouri Montana Airphoto-Jim Wark Note: water of the Missouri River has little sediment Vista: abaixo

Reservoir Francis Case Upriver from Fort Randall Dam in South Dakota Meade 2002 South Dakota

Fort Randall Dam Fort Randall Dam on Missouri River

Yankton South Dakota Gavins Point Dam on Missouri River Free-flowing Missouri River begins here

View: downriver from Gavins Point Dam Yankton Nebraska 1.8 million t/a

Rio Missouri Bodmer Loess bluffs Omaha, Nebraska Moody Eppley Airport Omaha Nebraska

Missouri River in Omaha, Nebraska Omaha Nebraska 26 million t/a

Nebraska Kansas Pile Dikes Indian Cave Bend View: downriver

Adapted from Funk and Robinson, % Water -41% Channels -99% Islands Channelization of Missouri River Reduced source of sediment and increased storage in new floodplains

Airphoto-Jim Wark View: Upriver Confluence of the Osage and Missouri Missouri Kansas

Photo: R. Stallard Missouri Storage of sediment behind dikes Missouri River at Mile 189 View: Downriver

Missouri River at Hermann, Missouri View: Upriver Hermann Missouri 88 million t/a

0 50 milhão t/a Adapted from Parker, 1988, IAHS Pub. 174 Increase in suspended sediment discharge principle from loess landscape in Iowa Iowa ~ 60 million t/a Total = 88 million t/a Missouri Iowa Confluence of the Missouri and Nishnabotna Rivers Missouri Yankton Hermann

Wing Dams or Rock Dikes L-Dikes View: below Hermann and upriver Missouri 400 m

Missouri Sand dredging in the Missouri River near St. Louis, Missouri

Missouri Illinois St. Louis Missouri Illinois St. Louis Mississippi in St. Louis, Missouri 97 million t/a View: from the left bank

Missouri Illinois Mississippi River at Cape Girardeau, Missouri View: Upriver Bank revetment

Mississippi River Upper Mile 51.0 Missouri Illinois L-Head dike

Missouri Illinois Mississippi River Upper Mile 37 Alternate dikes

Missouri Illinois Mississippi at Thebes, Illinois View: downriver The end of rocky outcrops along the banks

Missouri Kentucky Tennessee Ohio Mississippi Confluence of the Ohio and Mississippi Rivers View: downrivier 800 m

Mississippi River at Mile 388 Bank protection and trapping of the sediment Vegetation mat with rock protection at the toe of the bank Articulated concrete mat

Red River Mississippi River Atchafalaya River Mississippi River Tarbert Landing Knox Landing Simmesport Old River Outflow Channel Navigation Lock Low-sill Hydropower dam Auxiliary control Arkan- sas Louis- iana

Profundidade, m Q = 21,000 m 3 s -1 Lagura, m Velocity, m s Mississippi River at Arkan- sas Louis- iana Tarbert Landing, Mississippi 190 million t/a

Ohio Missouri Ohio Missouri Flux of water and suspended sediment from the Mississippi River Catchment about 1980

Louis- iana Lake Pontchartrain Mississippi River flowing through New Orleans Louis- iana

Mouth of the Mississippi River Gulf of México

Barrier island protection the coast of New Orleans

The mystery of the missing suspended sediment at Tarbert Landing Integrated bag sampler

Significant decline after 1800 Suspended sediment discharge, million t/a cerca de 1800 cerca de 1980cerca de 1800cerca de 1980about 1800about 1980

Sediment Water Mississippi River at Tarbert Landing Sediment Water Million t/a km 3 / a Water year in northern hemisphere (October through September) ~ 370 million t/a

Tarbert Landing Hermann Omaha Yankton Sediment Water = Amount entering between Omaha and Hermann km 3 / a Sediment Water 0 50 million t/a Adapted from Parker, 1988, IAHS Pub. 174 Hermann Omaha Milhões t/a Water year in the northern hemisphere

Other causes Annual suspended-sediment discharge, million metric tons Cumulative protection of the bank or cumulative construction of dikes, kilometers Bank protection dikes year ~ 150 million t/a ~ ??? million t/a

Other causes Soil conservation USDA Photo: Tim McCabe ~ 150 million t/a ~ ??? million t/a Area, ha Many small reservation in catchment of the Missouri River

Effect: Change in the C-Q relation Tarbert Landing C Mean annual concentration of suspended sediment, mg / L Q, Water discharge, km 3 / a Transport-limited system Supply-limited system ~ 150 million t/a ~ ??? million t/a

Our Conclusions and Thoughts 1.Some of the missing sediment is behind the large dams. 2.Structures like dikes and “wing dams”, designed to protect banks store sediment and prevent erosion of the sediment. 3.Soil conservation probable has bee effective in reducing the sediment discharge to the Missouri-Mississippi River system. 4. The Missouri-Mississippi system has changed from transport limited system to a supply-limited system.

5. Sediment deposition can be a problem and sediment deposition can be beneficial depending upon the human assessment of the situation.. 6. We need to continue to collect good data on sediment discharge. Good data lives forever and are fundament to modeling sediment transport. Good data lives forever and are fundament to modeling sediment transport. Models should only be used to synthesize the data. In the world of “non-stationary”, continuity of data is critical. Our Conclusions and Thoughts

7.The scientific paper in press on this subject could not have been possible without data collected over a long period of time (decades) 8. We need to understand river ecosystems completely and not only in terms of engineering structures. Our Conclusions and Thoughts

9. “Lean by listening and observing the river— each river is different.”. Our Conclusions and Thoughts

Obrigado por sua atenção. Questões?