The management of the Mississippi Jonathan W.F. Remo Associate Professor River System: an engineered legacy Director of Env. & Policy Program with a flood of future policy challenges Debris Removal “River Training” Greenville Mississippi 1927 Social Template: Management of the Mississippi River and its Major Tributaries Navigation – Commerce Clause – River and Harbors Act, 1824 Flood Control Act - 1928 Gavin's Point Dam, Missouri River Endangered Pallid Sturgeon Water Supply, Flood Control, and Power Generation - Flood NEPA, ESA – late 1960s – early 1970s and 1986 WRDA and Control Act of 1944 – Pick Sloan Missouri Basin Program Environmental Management Program - River Rehabilitation The Engineering Tool Kit: Navigation - River Training The Engineering Tool Kit: Navigation - Locks and Dams Lock and Dam Number 8 – La Crosse Wisconsin The Engineering Tool Kit: Navigation and Flood Risk Reduction - Reservoirs • 40,000 Reservoirs • ~440 km3 of storage • 1% of these dams account for 89% of storage Reservoir Impacts on Peak Flood Discharges Estimated Flood Peak Reduction by Model Reduction of Flood Discharges Reservoirs for the 1973 and 2011 Floods at St. Louis (USACE, 2004) (USACE, 1973 and DeHaan et al., 2012) Percent Chance Flood Peak Reduction Discharge Reduction Station Exceedance 1973 2011 0.2 -12% Alton -4% No Data 0.5 -15% St. Louis -6% No Data 1 -18% Cairo -15% <-2% 2 -17% Memphis -13% No Data 5 -17% 10 -18% Arkansas City -8% No Data 20 -17% Vicksburg -7% No Data 50 -19% Natchez -6% No Data Reservoir Impact on River Flows 25% - moderate and 75% - low flow exceedance Keeping Keeping the River the River Navigable Navigable Pre-rapid reservoir expansion Post-rapid reservoir expansion The Engineering Tool Kit: Navigation - Flood Risk Reduction - Cutoffs • 16 cutoffs between 1929 -1952 • Shortened river by 152 miles The Engineering Tool Kit: Flood Risk Reduction - Levees Cape Girardeau Floodwall – 2016 Flood • 90 levee systems • 4600 km of levees and floodwalls • 94,000 km2 of floodplain protected Saint Peters Levee – 2008 Flood The Engineering Tool Kit: Flood Risk Reduction - Floodways Birdspoint New Madrid Mississippi River Breach Floodway Old River Control Structure River Mississippi Bonnet Carre Spillway Spillway • The 100-year flood discharge has increased by 20% (± 7%) before major human impact to the river and its basin (1500-1800). • Climate – is attributed with 25% of the increase in the 100-year flood • 75% of the increase in the 100-year flood is attributed to human modifications of the river and its basin (i.e., landcover change and river engineering) Lower Mississippi River – Vicksburg Mississippi Attribution Science – hydrologic impacts of levees: Modern flood hydrograph run through the circa 1890s retro-model 13% lower discharge 25% lower discharge 1 day longer Memphis, TN 25 days longer Thebes, IL 14%for ~100 ~ 35--yearyear floodflood for ~180-year flood Impact of the MR&T Reservoirs? From Remo et al., 2018 Attribution - hydraulic impacts of river engineering: Modeled Changes in Water Surface Elevation 1880s to 2000s Middle Mississippi River – Missouri to Ohio River River Training Structures From Remo et al. 2009 Attribution - hydraulic impacts of river engineering: Modeled Changes in Water Surface Elevation Lower Mississippi River - Ohio River to Memphis Lower Mississippi River – Arkansas River to Natchez 1930s to 2000s 1970s to 2000s From Remo et al. 2009 River Engineering Impacts: Batture Land Sedimentation – Missouri River to Thebes, IL • DEMs 2011 – 1998 = sedimentation rate • 300 % Increase in Historic Sedimentation Rates • ~8.5 MT/yr-1 deposited in batture lands Julia From Remo et al., 2018 Summary of River Engineering Impacts: Levees, River Training, and Reservoirs -3% to -25% lower flood discharges 1,500 m 10 to >75 km 1859 Discharge River Stage River Segment River 3% to 25% higher High Low High Low Engineering Navigation flood discharge St. Paul to Rock Island 950 m Dams Navigation Rock Island to Missouri Dam, Reservoirs River and Levees Missouri River to River Training, Caruthersville, MO Reservoirs and Levees 0.5 to < 5.0 km * River Training, 2010s Caruthersville, MO to Reservoirs, Natchez, MS Cutoffs and Levees Illustrative Cross Section along the Open River, Modified from Stevens et al., 1975 Problems Structural Flood Mitigation: Maintenance 2008 Flood – Grand Tower Levee System Mississippi River System Levee’s and the National Levee Database Rating Level Rating Description Rating level of levees in Mississippi River Basin (2018) Acceptable All inspection items are rated as acceptable. One or more inspection items are rated as 15% minimally acceptable or one or more items are rated as unacceptable and an engineering 27% Minimally determination concludes that the 4% Acceptable unacceptable inspection items would NOT prevent the segment/system from performing as intended during the next flood event. One or more inspection items are rated as unacceptable and would prevent the segment/system from performing as intended, or a serious deficiency noted in past Unacceptable inspections (previous unacceptable items in a minimally acceptable overall rating) has not 54% been corrected within the established timeframe, not to exceed two years. Unacceptable Minimally Acceptable Acceptable No Data Levee Safety Ratings: Spring 2018 Levee Maintenance: May not be able to afford operation and maintenance costs? Building Exposure Agricultural Profit Per-Acre y = 0.2109x + 132.33 $600 y = 0.9534x $250 R² = 0.0063 R² = 0.1271 P > 0.2 P>0.2 $500 $200 Acre - $400 $150 $300 (Dollars) $100 $200 (Millions of (MillionsDollars) Estimated Building Exposure Building Estimated $50 $100 Agricultural Profit Per Profit Agricultural $- $- 0 20 40 60 80 100 120 0 20 40 60 80 100 120 Levee Protection Level Levee Protection Level (Return Period Years) (Return Period Years) Levee information for the Lower Illinois River - Peoria, IL to Mississippi River Confluence From Guida et al., 2016 Cost of the Upgrading: Upper Mississippi River Levee System Annualized Annualized Cost Benefit-to- Plan Protection Level Benefits Costs cost Ratio $ Billions $ Millions (2008) $ Millions (2008) 500-yr Urban B $ 5.01 $13.50 $ 327.24 0.04 500-yr Agriculture 500-yr Urban D $ 3.76 $12.29 $245.66 0.05 100-yr Agriculture 500-yr Urban E $ 2.91 $12.25 $ 189.90 0.06 “Variable” Agriculture 500-yr Urban J $ 3.20 Buyout Ag Structures NC $ 184.95 NC remove Ag Levees What is the big deal about the 1% chance flood? • Removes the area from FEMA’s flood rate insurance map special flood hazard area • Removes the requirement for flood insurance for residential structures with federally backed mortgages • Increases the value of the land • Reduces to cost of private insurance for business Upper Mississippi River “Levee Wars” Levee push up from the 2008 flood fight Rock Island District (USACE, 2017) Incomplete push down in Rock Island District after 2008 Flood (USACE, 2017) Upper Mississippi River “Levee Wars” Levees in red found to be 2 to 4 feet above design grade at an elevation like the 1% chance flood (100-year flood ) USACE’s Upper Mississippi River Flood Risk Management Model – HEC-RAS 1D/2D • Two model geometries: 1. Existing levee elevations 2. Federally-authorized design • Five flood scenarios used to assess the impact the differing levee elevations had on water-surface elevations and maximum flood depths 1. 2008 Flood 2. 2013 Flood 3. 2014 Flood 4. 2017 Flood 5. 1993 “Inflow Scenario” “Levee Wars” Difference in water levels between current and authorized levee elevations scenarios for the 2008 Flood From Remo, 2018 “Levee Wars” Changes in flood depths between authorized and actual levee elevations for the 1993 flood scenario From Remo, 2018 Calculating changes in flood losses using HAZUS-MH 5. Estimated economic losses 4. Determine loss estimates for each scenario and flood return period 3. Define and overlay building, infrastructure and agricultural inventory 2. Define hazard using a flood-depth grids generated from the Upper Mississippi Flood Risk Management HEC-RAS Model 1. Define study region and DEM “Levee Wars” Changes in expected annual damages for buildings $600,000.00 $550,000 $400,000.00 Other Levee districts with levees Floodplain at authorized elevations $200,000.00 Areas and unprotected areas $- 1 Levee districts with $(200,000.00) levees above authorized elevations $(400,000.00) - $401,000 $(600,000.00) “Levee Wars” Changes in agricultural expected annual damages (EAD) Conclusions: Engineering the Mississippi River for its current suite of services have resulted in unintended consequences such as: 1. Increase in flood discharges 2. Higher flood levels 3. Increase flood exposure 4. In some cases increasingly unsustainable river and flood mitigation infrastructure Len Small Levee-Alexander County, Illinois 2015-2016 Flood Conclusions: • More affluent river stakeholders along portions of the UMR have undertaken actions exceeding federally approved and locally adopted floodplain management agreements and ordnances increasing flood risk to adjacent lands, especially during large floods (i.e., >100 year event) • The long-term operational and maintenance costs of some river and several flood mitigation infrastructure coupled with conflicting policy goals have resulted in unsustainable river management objectives • Substantial management, policy, and funding challenges need to be addressed in order to sustain the current level of ecosystem services the Mississippi River has historically provided. Len Small Levee-Alexander County, Illinois 2015-2016 Flood Questions? Cap au Gris Levee near Winfield, MO 2008 Upper Mississippi River Flood Jonathan W.F. Remo (diamict @ siu.edu) Associate Professor - Geography and Environmental Resources, School of Earth Systems and Sustainability Southern Illinois University Carbondale References: Munoz S.E., Giosan L., Therrell, M.D., Remo, J.W.F., Shen Z., Sullivan, R.M., Wiman, C., O’Donnell, M., Donnelly, J.P. 2018. Mississippi River flood hazard amplified by climate variability and river engineering, Nature. v. 556, 95–98. doi:10.1038/nature26145 Remo, J.W.F., Ryherd, J.K., Ruffner, C.M. Therrell, M.D. 2018. Temporal and spatial patterns of sedimentation within the batture lands of the middle Mississippi River, USA.