DESIGN OF DIVERSIONS OF THE MISSISSIPPI RIVER TO BUILD NEW LAND IN SOUTHERN LOUISIANA

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DESIGN OF DIVERSIONS OF THE MISSISSIPPI RIVER TO BUILD NEW LAND IN SOUTHERN LOUISIANA Gary Parker, University of Illinois Urbana-Champaign along with Matthew Czapiga,

1 DESIGN OF DIVERSIONS OF THE MISSISSIPPI RIVER TO BUILD NEW LAND IN SOUTHERN LOUISIANA Gary Parker, University of Illinois Urbana-Champaign along with Matthew Czapiga, Benjamin Hobbs, Melissa Kenney, Wonsuck Kim, David Mohrig, Jeffrey Nittrouer, Chris Paola, Robert Twilley, Enrica Viparelli and many others Presented at Roma Tre, Italy May 23,

2 PROFESSOR ENRICO MARCHI HAS A QUESTION Gary, did you not give a presentation on the same topic in 2008? 2

3 REHABILITATION OF THE MISSISSIPPI DELTA WITH SOME COMPARISONS WITH VENICE LAGOON Wonsuck Kim & Gary Parker, University of Illinois As part of a much larger team led by C. Paola (NCED) and R. Twilley (CLEAR) Presented at the Italian National Academy of the Lynxes Rome, June 5, 2008 Accademia Nazionale dei Lincei XXVI GIORNATA DELL AMBIENTE Convegno La salvaguardia di Venezia e della sua laguna in ricordo di Enrico Marchi giovedì 5 giugno

4 PROFESSOR MARCHI HAS ANOTHER QUESTION Tell me, Gary, it is now 2014, have you found anything new since 2008? 4

5 SO LET US BEGIN WITH A RECAPITULATION OF THE PROBLEM Mississippi River Delta 5

6 THE DELTA IS SINKING INTO THE SEA DUE TO SUBSIDENCE AND SEA LEVEL RISE highest land loss rates 6

7 CAN WE AMELIORATE THIS LOSS OF LAND? CAN WE BUILD NEW LAND? Or should we surrender and abandon the delta? 7

8 DEFEATIST ARGUMENT NO. 1 I believe the Bush administration should continue to withhold money for coastal restoration in Louisiana. The projects being served up by the U.S. Army Corps of Engineers are little more than traditional Louisiana pork. Most of the Mississippi Delta, some 10,000 square miles, lies less than three feet above sea level. Beset by land subsidence and rising sea levels, much of this vast area will inexorably sink beneath the waters by the end of this century. Congress should suspend all coastal funding until the Corps and Louisiana prepare a comprehensive and realistic land-use plan for the entire delta, applying modern science and fiscal discipline to determine what can and cannot be salvaged. BRUCE BABBITT Former Secretary of the Interior 8

9 More defeatism Blum and Roberts (2009) 9

10 More defeatism Blum and Roberts (2009) BUT WHERE IS 10 THE SEDIMENT?

11 OUR RESPONSE: THE MISISSIPPI RIVER HAS A VERY LARGE DRAINAGE BASIN 11

12 THE SEDIMENT SUPPLY TO THE LOWER MISSISSIPPI RIVER HAS BEEN REDUCED BY DAMS ON THE MISSOURI RIVER Missouri River Basin 12

13 SINCE ABOUT 1950, FIVE MAJOR DAMS HINDER THE PASSAGE OF SEDIMENT ON THE MISSOURI RIVER Garrison Dam and Lake Sakakawea, Missouri River: ~ 240 km of backwater 13

14 IT IS CLAIMED THAT THE SEDIMENT SUPPLY TO THE LOWER MISSISSIPPI HAS DECLINED (BUT SEE BELOW) 14

15 BUT THE LOWER MISSISSIPPI RIVER, AND ITS DISTRIBUTARY, THE ATCHAFALAYA RIVER STILL CARRY A LOT OF SEDIMENT Input: ~ 208 Mt/yr Atchafalaya River: ~ 84 Mt/yr Lower Mississippi River: ~ 124 Mt/yr Wax Lake Delta: ~ Mt/yr Main Mississippi Delta Suspended sediment loads Atchafalaya Delta: ~ Mt/yr 15

16 THE SEDIMENT ON THE MAIN-STEM MISSISSIPPI RIVER IS WASTED, BECAUSE LEVEES FORCE DELIVERY TO THE SEA 16

17 BUT THE RELATIVELY NEW, UNLEVEED ATCHAFALAYA RIVER SYSTEM HAS PRODUCED A LOT OF LAND: FIRST INLAND, Roberts et al. 1997

18 AND THEN AS NEW SHORELINE Mississippi River Atchafalaya River Wax Lake and Atchafalaya Deltas 18

19 WAX LAKE AND ATCHAFALAYA DELTAS 19

20 WAX LAKE DELTA: NEW LAND SINCE 1980, EMPLACED A PLATFORM CONTAININING 70% SAND An extensive data base dating from its genesis is available 20

21 WE NEED SAND TO BUILD NEW LAND Mississippi River sediment load at St. Francis: ~ 18% sand, 82% mud Wax Lake delta deposits (open shelf): ~ 67% sand, 33% mud THE SAND COMES FIRST AND THE MUD FOLLOWS Cour. Jeff Nittrouer 21

22 WE BUILT A MORPHODYNAMIC MODEL OF FAN-DELTA FORMATION WITH A SAND-MUD PARTITION AND VERIFIED IT WITH THE WAX LAKE DELTA Before start of delta growth 22

23 THE MODEL CAN REPRODUCE THE WAX LAKE DELTA S PAST Yellow: 38 Mt/yr White: 25 Mt/yr (suspended load) 23

24 THE MODEL CAN REPRODUCE THE WAX LAKE DELTA S PAST Yellow: 38 Mt/yr White: 25 Mt/yr (suspended load) 24

25 THE MODEL CAN REPRODUCE THE WAX LAKE DELTA S PAST Yellow: 38 Mt/yr White: 25 Mt/yr (suspended load) 25

26 THE MODEL CAN REPRODUCE THE WAX LAKE DELTA S PAST Yellow: 38 Mt/yr White: 25 Mt/yr (suspended load) 26

27 SAMPLE MIGRATION OF THE MODEL FROM WAX LAKE TO THE MISSISSIPPI RIVER BELOW NEW ORLEANS: Two diversions: Barataria Bay and Breton Sound (CLEAR plan) 27

28 POTENTIAL SEDIMENT FOR DELTA BUILDING: 45% OF 124 Mt/yr, OR 56 Mt/yr 45% of floodwater and sediment diverted. Breton Sound: 28 Mt/yr delivered 11 Mt/yr captured Barataria Bay: 28 Mt/yr delivered 11 Mt/yr captured 28

29 SCENARIOS MODELED 100 year simulations from 2010 Base case shown here: Subsidence: 5 mm/yr; sea level rise: 2 mm/yr Variant parameters Subsidence: 1 mm/yr, 10 mm/yr Sea level rise: 0 mm/yr, 4 mm/yr Image from M. Wolinsky 29

30 PRELIMINARY RESULTS FOR LAND-BUILDING: BASE CASE Takes only about 0.1 years to build these initial deltas 30

31 BASE CASE: SEA-LEVEL RISE RATE = 2 mm/yr, SUBSIDENCE = 5 mm/yr 31

32 BASE CASE 32

33 BASE CASE 33

34 BASE CASE 34

35 BASE CASE 35

36 BASE CASE 36

37 BASE CASE 37

38 BASE CASE 38

39 WORST CASE VARIATION: SEA-LEVEL RISE = 4 mm/yr, SUBSIDENCE = 10 mm/yr Solid line: variant case Dotted line: base case 39

40 WE PUBLISHED THIS WORK IN 2009 Enrico: this is how far we had progressed by the time of the Accademia dei Lincei talk of

41 DEFEATIST ARGUMENT NO. 2 It doesn t matter how deep you go, you will get only mud, and you cannot build new land out of mud 41

42 OPPORTUNITY: HISTORIC FLOOD OF MISSISSIPPI RIVER OF 2011 Confluence of Mississippi and Ohio Rivers, 2011 flood 42

2011 Mississippi River Flood facts: --2 nd largest recorded flood of modern era Morganza Spillway Mississippi River Bonnet Carré Spillway: --During

43 2011 Mississippi River Flood facts: --2 nd largest recorded flood of modern era Morganza Spillway Mississippi River Bonnet Carré Spillway: --During operation in 2011, the Bonnet Carré Spillway became the 3 rd largest river in the U.S. (by discharge) Lake Pontchartrain Bonnet Carré Spillway Gulf of Mexico

44 350 m BONNET CARRE SPILLWAY IN FLOOD OF 2011 WAS OPEN FOR 30 DAYS Bonnet Carré Spillway Structure

45 Bonnet Carré Spillway Structure AN OCEAN OF SAND DEPOSITED

46 10 m H= m λ=10-30 m

47 CONFIGURATION OF BEND AIDED SAND DELIVERY FROM CHANNEL

48 Measured sand deposit in spillway: 4 x 10 6 m 3 -Calculated from delineation of sand areas and their measured depths Predicted sand leaving Mississippi River during 2011 flood: 4.5 x 10 6 m 3 -Calculated via physical model sediment concentration from rouse profile coupled with measured spillway discharge Total sediment flux during 2011 flood: x 10 6 m 3 -Calculated from measured suspended sediment load at Belle Chase, LA plus a bedload ratio Proportion of total sand exported from Mississippi River: ~30%

49 WE PUBLISHED THIS WORK IN 2012 Enrico: we ve made progress on proof of concept in regard to the ability to divert sand. 49

50 ENRICO AT HANEDA AIRPORT, JAPAN, ~ 1995 THIS, IS NOT COFFEE! 50

51 DEFEATIST ARGUMENT NO. 3 A large diversion structure is too costly, and cannot be designed for the very low heads of the Mississippi River downstream of New Orleans SO WE DESIGNED AND COSTED OUR OWN STRUCTURE 51

52 CULVERT DESIGN 52

53 EXAMPLES OF SMALL CONTROLLED DIVERSIONS ON THE MISSISSIPPI RIVER Caernarvon Diversion Culvert design Suitable for deep diversions with low head But captures mostly mud, not sand 53

54 BACK TO CULVERT DESIGN Q = N BH 2g ( ξ ξ ) m t c 2 u 1+ Ke + 4/3 KnL R Culvert discharge/head relation + Velocity profile in river during floods + Suspended sand profile in river during floods = Completely submerged inlet and outlet conditions ~ 2 m of head between river in flood and backwater Calculator for diversion design 54

55 SUSPENDED SAND DISTRIBUTIONS IN WATER COLUMN OF MISSISSIPPI RIVER The deep our culvert, the more sand we get 55

56 DESIGN BASED ON STACKED ROWS OF 8m X 8m CULVERTS Levee Top Z t D W Z b River Bottom 56

57 LAND BUILDING OVER 50 YEARS PREDICTED BY THE WAX LAKE MODEL MIGRATED TO LOWER MISSISSIPPOI DIVERSION Sand = sand discharge during floods Water = H2O = water discharge during floods = Sand Water

58 COST OF CURRENT DIVERSIONS (NOT BUILT OR MANAGED TO MAXIMIZE LAND BUILDING) Depth D (m) Width W (m) Cost (2010$) Bonnet Carre ,000,000 Caernarvon Diversion ,300,000 Davis Pond ,000,000 Old River Control Structure ,000,000 West Bay ,920,000 58

59 SINGLE PROJECT: COST OF LAND BUILDING (Rouse Sand-Depth Function, Strong Scale Economies Cost Function) Water diversion limit means we must go deep for most land 8m x 8m culvert design D c = 40 m B c = 240 m Cost ~ 2.5 Billion $ 59

60 $2.5 BILLION TOO EXPENSIVE? Cost of Iraq War: at least $760 billion 60

61 WE PUBLISHED THIS WORK IN 2013 Enrico: we ve made progress on the design and costing of a diversion structure 61

62 DEFEATIST ARGUMENT NO. 3 The sediment load on the Mississippi River is declining, so there will not be enough sediment available in the future to build land Mississippi River at Knox Landing (near Tarbert Landing From Horowitz,

63 THIS DECLINE IS ASCRIBED MOSTLY TO THE DAMS ON THE MISSOURI RIVER Garrison Dam and Lake Sakakawea, Missouri River: ~ 240 km of backwater 63

64 BUT WE NEED SAND TO BUILD NEW LAND IS THE SAND SUPPLY TO THE DELTA REALLY DECLINING? Gaging Sites at Thebes and Tarbert Landing 64

TOTAL SUSPENDED SEDIMENT LOAD IS DECLINING Mean annual suspended total (sand + mud) load (Million tons/yr) 180 160 140 120 100 80 60 40 20 0

65 TOTAL SUSPENDED SEDIMENT LOAD IS DECLINING Mean annual suspended total (sand + mud) load (Million tons/yr) Misissippi River at Tarbert Landing Mississippi River at Thebes

66 SAND LOAD IS DECLINING AT THEBES Mean annual suspended load (Million tons/yr) Mississippi River at Thebes sand mud

67 SAND LOAD IS NOT DECLINING AT TARBERT LANDING Mean annual suspended load (Million tons/yr) Mississippi River at Tarbert Landing sand mud

68 WHY? OVER 1500 KM OF SAND IN THE MISSISSIPPI ACTS LIKE A GIANT CAPACITOR This sand is available to compensate for the decline due to Missouri River dams 68

69 MISSISSIPPI RIVER NEAR ST. LOUIS: STILL ALLUVIAL- SAND BED (note bridge pier scour) 69

70 A SIMPLE NUMERICAL MODEL Single channel Constant width Single sand grain size No tributaries Allow sediment supply to channel via migration Reduce sand supply to ¼ of ambient value at upstream end 70

71 50 45 SAND SUPPLY 200 YEARS FROM NOW Knox Landing Sand Load (Mt/yr) Load 0 yr Load 40 yr Load 80 yr Load 120 yr Load 160 yr Load 200 yr Red River Landing Memphis Memphis Cairo Thebes River km upstream of Head of Passes 71

72 50 45 SAND SUPPLY 1000 YEARS FROM NOW Knox Landing Sand Load (Mt/yr) Load 0 yr Load 200 yr Load 400 yr Load 600 yr Load 800 yr Load 1000 yr Red River Landing Memphis Memphis Cairo Thebes River km upstream of Head of Passes 72

73 WE PUBLISHED THIS WORK IN 2014 Sand supply will not show noticeable decline for several decades! Enrico: we ve made progress on the future supply of sand for land building 73

74 DEFEATIST ARGUMENT NO. 4 Diversions will render the lower Mississippi River unnavigable 74

75 SO WE MODELED THE EFFECT OF DIVERSIONS ON THE MAIN- STEM MISSISSIPPI RIVER Two potential diversion sites 75

76 IN 150 YEARS, THE DIVERSIONS PRODUCE ~ 3.5 M OF AGGRADATION DOWNSTREAM, IN A RIVER WITH A BANKFULL DEPTH ~ 40 m AND AN AVERAGE DEPTH ~ 30 m Distance above head of passes in km 76

77 WE ARE JUST ABOUT TO SUBMIT THIS WORK Journal of Geophysical Research Modeling of a reach of the lower Mississippi River, Louisiana, USA with an upstream alluvial-bedrock transition and a downstream bedrock-alluvial transition: implications for land-building using engineered diversions. Enrica Viparelli, Jeffrey A. Nittrouer, Gary Parker Enrico: we ve established that diversions can be designed to have only modest effects on navigation 77

78 CHIARISSIMO MARCHI, WE ARE STILL NOT FINISHED, BUT WE HAVE BEEN INSPIRED BY YOU!

Optimal Design of Sediment Diversions for Delta Restoration: lessons learned from examples

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