Mississippi Valley Division Engineer Research and Development Center

Hydraulic Analysis and 

Modeling of Navigation 

Conditions through the 

Mississippi River Bridges

Reach in Vicksburg, 

Mississippi

MRG&P Report No. 33 • May 2020

Mississippi River Geomorphology and 

Potamology Program 

MRG&P Report No. 33 

May 2020 

Hydraulic Analysis and Modeling of Navigation 

Conditions through the Mississippi River 

Bridges Reach in Vicksburg, Mississippi

Keaton E. Jones, Tate O. McAlpin, and Terry N. Waller 

Coastal and Hydraulics Laboratory

US Army Engineer Research and Development Center

3909 Halls Ferry Rd

Vicksburg, MS 39180-6199

Final report 

Approved for public release; distribution is unlimited. 

Prepared for US Army Corps of Engineers, Vicksburg District

4155 Clay Street 

Vicksburg, MS 39183

Under Project 107202, “Mississippi River and Tributaries Project, Channel 

Improvement, Dikes Construction”
MRG&P Report No. 33 ii

Abstract

The River and Estuarine Engineering Branch of the Coastal and 

Hydraulics Laboratory developed a two-dimensional numerical model of 

the Mississippi River near Vicksburg, MS, using Adaptive Hydraulics to 

investigate navigation conditions through the Interstate 20 and Old 

Highway 80 Bridges reach. A focus of the study was determining the 

Marshall Brown Dikes impact to velocities and navigation through the 

reach. Proposed dikes, focused on improving currents, were also tested to 

determine if they are a feasible option to improve navigability through the 

bridges. A second proposed alternative, a levee to protect the articulated 

concrete mattress (ACM) field, was also simulated to determine if flood 

damage to the ACM field could be successfully reduced without negatively 

impacting navigation. Velocity data from 2008 throughout the reach of 

concern were used for validation along with water surface elevation data 

from 2008, 2011, 2016, and 2018. The Marshall Brown Dikes were shown 

to have a localized impact on velocities near the dikes, but the changes to 

the velocity downstream near the bridge were negligible for all tested flow 

rates. Simulations of the proposed dikes did not result in an improvement 

to navigation conditions, but the proposed levee was successful in 

decreasing velocities and depths over the ACM field.

DISCLAIMER: The contents of this report are not to be used for advertising, publication, or promotional purposes. 

Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products. 

All product names and trademarks cited are the property of their respective owners. The findings of this report are not to 

be construed as an official Department of the Army position unless so designated by other authorized documents.

DESTROY THIS REPORT WHEN NO LONGER NEEDED. DO NOT RETURN IT TO THE ORIGINATOR.
MRG&P Report No. 33 iii

Contents

Abstract................................................................................................................................................... ii

Figures and Tables..................................................................................................................................v

Preface.....................................................................................................................................................x

1 Introduction.....................................................................................................................................1

1.1 Background.................................................................................................................... 1

1.2 Objective ......................................................................................................................10

1.3 Approach......................................................................................................................10

2 Model Development.....................................................................................................................11

2.1 Mesh development......................................................................................................12

2.2 Boundary conditions ...................................................................................................21

3 Validation to Past Floods.............................................................................................................24

3.1 2008 ............................................................................................................................24

3.1.1 2008 velocity comparisons ......................................................................................26

3.1.2 2008 gage and water surface elevations comparisons .........................................44

3.2 2011.............................................................................................................................46

3.3 2016.............................................................................................................................50

3.4 2018.............................................................................................................................52

4 Evaluation of Marshall Brown Dikes..........................................................................................54

4.1 With and without Marshall Brown Dikes ....................................................................54

4.1.1 High flow for with and without Marshall Brown Dikes ............................................55

4.1.2 Medium flow for with and without Marshall Brown Dikes ......................................64

4.1.3 Low flow for with and without Marshall Brown Dikes .............................................69

4.2 Evaluation of the impact of the Marshall Brown Dikes with geomorphic 

changes ..................................................................................................................................75

5 Proposed Alternatives..................................................................................................................90

5.1.1 High flow.................................................................................................................... 91

5.1.2 Medium flow..............................................................................................................99

5.1.3 Low flow...................................................................................................................104

6 Conclusions and Recommendations ...................................................................................... 109

References......................................................................................................................................... 111

Appendix A: Navigation Charts........................................................................................................ 112

Appendix B: Top 9 ft Velocities........................................................................................................ 115

Unit Conversion Factors................................................................................................................... 125
MRG&P Report No. 33 iv

Acronyms and Abbreviations........................................................................................................... 126

Report Documentation Page
MRG&P Report No. 33 v

Figures and Tables

Figures

Figure 1. Location map and relevant features. ....................................................................................... 2

Figure 2. Navigation pass (upstream looking downstream). ................................................................. 3

Figure 3. Marshall Brown Dikes (Dike 1, 2, 3, and 4)............................................................................. 4

Figure 4. Marshall Brown bank retreat. ................................................................................................... 6

Figure 5. Proposed dikes’ locations.......................................................................................................... 7

Figure 6. Mat field flooding. ...................................................................................................................... 9

Figure 7. Helical flow illustration in a river bend (ERDC-CHL 2017). ...................................................11

Figure 8. Model limits. .............................................................................................................................12

Figure 9. Mesh resolution........................................................................................................................13

Figure 10. Material type locations. .........................................................................................................14

Figure 11. Bathymetry dataset. ..............................................................................................................16

Figure 12. 2008 Mesh elevation............................................................................................................ 17

Figure 13. 2011 Mesh elevation. ...........................................................................................................18

Figure 14. 2016 Mesh elevation.............................................................................................................19

Figure 15. 2018 Mesh elevation. ...........................................................................................................20

Figure 16. Mississippi River inflow hydrographs. ..................................................................................22

Figure 17. Yazoo River inflow hydrographs.............................................................................................23

Figure 18. Downstream stage hydrographs. .........................................................................................23

Figure 19. April 9, 2008 transect locations...........................................................................................25

Figure 20. Drogue. ...................................................................................................................................25

Figure 21. April 9, 2008 depth averaged velocity plan view comparison for Transects 2, 4, 

6, 8, 10, 12, 14, and 16 (modeled on left, measured in middle, both on right)................................ 27

Figure 22. April 9, 2008 top 9 ft velocity plan view comparison for Transects 2, 4, 6, 8, 10, 

12, 14, and 16 (modeled on left, measured in middle, both on right). .............................................. 27

Figure 23. April 9, 2008 depth averaged velocity plan view comparison for Transects 121, 

22, 20, and 18 (modeled on top and measured on bottom). .............................................................28

Figure 24. April 9, 2008 top 9 ft velocity plan view comparison for Transects 22, 20, and 

18 (modeled on top and measured on bottom)....................................................................................29

Figure 25. 2008 Transect 121 depth, velocity, and unit discharge comparisons.............................30

Figure 26. 2008 Transect 22 depth, velocity, and unit discharge comparisons. .............................. 31

Figure 27. 2008 Transect 20 depth, velocity, and unit discharge comparisons................................32

Figure 28. 2008 Transect 18 depth, velocity, and unit discharge comparisons. ..............................33

Figure 29. 2008 Transect 16 depth, velocity, and unit discharge comparisons. ..............................34

Figure 30. 2008 Transect 14 depth, velocity, and unit discharge comparisons. ..............................35

Figure 31. 2008 Transect 12 depth, velocity, and unit discharge comparisons................................36

Figure 32. 2008 Transect 10 depth, velocity, and unit discharge comparisons. .............................. 37

Figure 33. 2008 Transect 8 depth, velocity, and unit discharge comparisons..................................38
MRG&P Report No. 33 vi

Figure 34. 2008 Transect 6 depth, velocity, and unit discharge comparisons..................................39

Figure 35. 2008 Transect 4 depth, velocity, and unit discharge comparisons..................................40

Figure 36. 2008 Transect 2 depth, velocity, and unit discharge comparisons.................................. 41

Figure 37. May 1, 2008 ADCP velocity comparisons............................................................................42

Figure 38. Drogue paths (left image is observations and right image is model results). .................43

Figure 39. 2008 stage comparison with USACE gage..........................................................................44

Figure 40. 2008 total discharge comparison with USGS gage. ..........................................................44

Figure 41. 2008 water surface elevation profile location. ...................................................................45

Figure 42. April 21, 2008, water surface elevation profile comparison. ............................................45

Figure 43. 2011 stage comparison with USACE gage.......................................................................... 47

Figure 44. 2011 total discharge comparison with USGS gage............................................................ 47

Figure 45. 2011 water surface elevation profile locations. .................................................................48

Figure 46. May 18, 2011, Profile 1 water surface elevation comparison. .........................................48

Figure 47. May 19, 2011, Profile 2 water surface elevation comparison...........................................49

Figure 48. May 20, 2011, Profile 3 water surface elevation comparison. .........................................49

Figure 49. 2016 stage comparison with USACE gage..........................................................................50

Figure 50. 2016 total discharge comparison with USGS gage............................................................ 51

Figure 51. 2016 water surface elevation profile location..................................................................... 51

Figure 52. January 17, 2016, water surface elevation profile comparison........................................52

Figure 53. 2018 stage comparison with USACE gage..........................................................................52

Figure 54. 2018 total discharge comparison with USGS gage............................................................53

Figure 55. Mesh elevations for without and with Marshall Brown Dikes............................................55

Figure 56. High flow velocities for 2018 (with dikes – left, without dikes - right). .............................56

Figure 57. High flow velocity difference for with and without Marshall Brown Dikes 

(2018 dikes removed minus 2018). ...................................................................................................... 57

Figure 58. Velocity comparison transect locations. ..............................................................................58

Figure 59. With (2018) and without (2018 dikes removed) Marshall Brown Dikes Transect 

1 velocity comparison for high flow. .......................................................................................................58

Figure 60. With (2018) and without (2018 dikes removed) Marshall Brown Dikes Transect 

2 velocity comparison for high flow. .......................................................................................................59

Figure 61. With (2018) and without (2018 dikes removed) Marshall Brown Dikes Transect 

3 velocity comparison for high flow. .......................................................................................................59

Figure 62. With (2018) and without (2018 dikes removed) Marshall Brown Dikes Transect 

4 velocity comparison for high flow. .......................................................................................................60

Figure 63. With (2018) and without (2018 dikes removed) Marshall Brown Dikes Transect 

5 velocity comparison for high flow. .......................................................................................................60

Figure 64. With (2018) and without (2018 dikes removed) Marshall Brown Dikes Water 

surface elevation profile comparison locations. ................................................................................... 61

Figure 65. 2018 high flow water surface elevation. .............................................................................62

Figure 66. With (2018) and without (2018 dikes removed) Marshall Brown Dikes water 

surface elevation Profile 1 comparison for high flow............................................................................63

Figure 67. With (2018) and without (2018 dikes removed) Marshall Brown Dikes water 

surface elevation Profile 2 comparison for high flow............................................................................63
MRG&P Report No. 33 vii

Figure 68. Medium flow velocity difference for with and without Marshall Brown Dikes 

(2018 dikes removed minus 2018) . .....................................................................................................64

Figure 69. With (2018) and without (2018 dikes removed) Marshall Brown Dikes Transect 

1 velocity comparison for medium flow..................................................................................................65

Figure 70. With (2018) and without (2018 dikes removed) Marshall Brown Dikes Transect 

2 velocity comparison for medium flow..................................................................................................65

Figure 71. With (2018) and without (2018 dikes removed) Marshall Brown Dikes Transect 

3 velocity comparison for medium flow..................................................................................................66

Figure 72. With (2018) and without (2018 dikes removed) Marshall Brown Dikes Transect 

4 velocity comparison for medium flow..................................................................................................66

Figure 73. With (2018) and without (2018 dikes removed) Marshall Brown Dikes Transect 

5 velocity comparison for medium flow..................................................................................................67

Figure 74. 2018 medium flow water surface elevation........................................................................67

Figure 75. With (2018) and without (2018 dikes removed) Marshall Brown Dikes water 

surface elevation Profile 1 comparison for medium flow.....................................................................68

Figure 76. With (2018) and without (2018 dikes removed) Marshall Brown Dikes water 

surface elevation Profile 2 comparison for medium flow.....................................................................68

Figure 77. High flow velocity difference for with and without Marshall Brown Dikes 

(2018 dikes removed minus 2018). ......................................................................................................69

Figure 78. With (2018) and without (2018 dikes removed) Marshall Brown Dikes Transect 

1 velocity comparison for low flow..........................................................................................................70

Figure 79. With (2018) and without (2018 dikes removed) Marshall Brown Dikes Transect 

2 velocity comparison for low flow..........................................................................................................70

Figure 80. With (2018) and without (2018 dikes removed) Marshall Brown Dikes Transect 

3 velocity comparison for low flow.......................................................................................................... 71

Figure 81. With (2018) and without (2018 dikes removed) Marshall Brown Dikes Transect 

4 velocity comparison for low flow.......................................................................................................... 71

Figure 82. With (2018) and without (2018 dikes removed) Marshall Brown Dikes Transect 

5 velocity comparison for low flow..........................................................................................................72

Figure 83. 2018 low flow water surface elevation................................................................................73

Figure 84. With (2018) and without (2018 dikes removed) Marshall Brown Dikes Water 

surface elevation Profile 1 comparison for low flow. .............................................................................74

Figure 85. With (2018) and without (2018 dikes removed) Marshall Brown Dikes Water 

surface elevation Profile 2 comparison for low flow. .............................................................................74

Figure 86. High flow velocities for 2008................................................................................................ 76

Figure 87. High flow velocities for 2011.................................................................................................77

Figure 88. High flow velocities for 2016. ...............................................................................................78

Figure 89. High flow velocities for 2018. ...............................................................................................79

Figure 90. High flow velocity differences 2008 to 2018 (2018 minus 2008)...................................80

Figure 91. High flow velocity differences 2011 to 2018 (2018 minus 2011). ..................................81

Figure 92. High flow velocity differences 2016 to 2018 (2018 minus 2016). ..................................82

Figure 93. Difference in velocities from 2008 to 2011 (2011 minus 2008).....................................83

Figure 94. Difference in velocities from 2011 to 2016 (2016 minus 2011). ....................................84

Figure 95. Difference in velocities from 2016 to 2018 (2018 minus 2016). ....................................85
MRG&P Report No. 33 viii

Figure 96. Transect 1 multi-year comparison........................................................................................86

Figure 97. Transect 2 multi-year comparison.........................................................................................86

Figure 98. Transect 3 multi-year comparison........................................................................................ 87

Figure 99. Transect 4 multi-year comparison........................................................................................ 87

Figure 100. Transect 5 multi-year comparison...................................................................................... 87

Figure 101. Multi-year water surface elevation Profile 1 comparison.................................................88

Figure 102. Multi-year water surface elevation Profile 2 comparison. ...............................................89

Figure 103. Proposed dikes and levee...................................................................................................91

Figure 104. High flow alternative velocity (2018 existing – left; alternative dikes – middle; 

alternative dikes minus 2018 existing – right)......................................................................................92

Figure 105. Transect 1 alternatives velocity comparison for high flow...............................................93

Figure 106. Transect 2 alternatives velocity comparison for high flow...............................................94

Figure 107. Transect 3 alternatives velocity comparison for high flow................................................94

Figure 108. Transect 4 alternatives velocity comparison for high flow...............................................95

Figure 109. Transect 5 alternatives velocity comparison for high flow...............................................95

Figure 110. High flow alternative velocity (2018 existing – left; alternative levee – middle; 

alternative levee minus 2018 existing – right)......................................................................................96

Figure 111. Alternatives water surface elevation Profile 1 comparison for high flow........................ 97

Figure 112. Alternatives water surface elevation Profile 2 comparison for high flow. ......................98

Figure 113. High flow depth reduction due to levee alternative..........................................................99

Figure 114. Medium flow alternative velocity (2018 existing – left; alternative dikes –

middle; alternative dikes minus 2018 existing – right). .....................................................................100

Figure 115. Transect 1 alternatives velocity comparison for medium flow. .....................................101

Figure 116. Transect 2 alternatives velocity comparison for medium flow. .....................................101

Figure 117. Transect 3 alternatives velocity comparison for medium flow.......................................101

Figure 118. Transect 4 alternatives velocity comparison for medium flow. .....................................102

Figure 119. Transect 5 alternatives velocity comparison for medium flow. .....................................102

Figure 120. Alternatives water surface elevation Profile 1 comparison for medium flow. .............103

Figure 121. Alternatives water surface elevation Profile 2 comparison for medium flow...............103

Figure 122. Low flow alternative velocity (2018 existing – left; alternative dikes – middle; 

alternative dikes minus 2018 existing – right)....................................................................................105

Figure 123. Transect 1 alternatives velocity comparison for low flow...............................................106

Figure 124. Transect 2 alternatives velocity comparison for low flow...............................................106

Figure 125. Transect 3 alternatives velocity comparison for low flow...............................................106

Figure 126. Transect 4 alternatives velocity comparison for low flow...............................................107

Figure 127. Transect 5 alternatives velocity comparison for low flow. ..............................................107

Figure 128. Alternatives water surface elevation Profile 1 comparison for low flow.......................108

Figure 129. Alternatives water surface elevation Profile 2 comparison for low flow.......................108

Figure 130. Vicksburg bridges navigation chart (USACE 2015)........................................................113

Figure 131. RM 443.1 to RM 428 navigation chart (USACE 2015)..................................................114

Figure 132. High flow 2018 9 ft velocity..............................................................................................115
MRG&P Report No. 33 ix

Figure 133. High flow 2018 dikes removed 9 ft velocity....................................................................116

Figure 134. High flow 9 ft velocity difference (2018 dikes removed minus 2018).........................117

Figure 135. Medium flow 2018 9 ft velocity. ......................................................................................118

Figure 136. Medium flow 2018 dikes removed 9 ft velocity. ............................................................119

Figure 137. Medium flow 9 ft velocity difference (2018 dikes removed minus 2018)...................120

Figure 138. Low flow 2018 9 ft velocity...............................................................................................121

Figure 139. Low flow 2018 dikes removed 9 ft velocity.....................................................................122

Figure 140. Low flow 9 ft velocity difference (2018 dikes removed minus 2018)..........................123

Figure 141. High flow alternative 9 ft velocity (2018 existing – left; alternative dikes –

middle; alternative dikes minus 2018 existing – right). .....................................................................124

Tables

Table 1. Material types and friction for 2008 (Note: some dike material types are assigned 

the same roughness as the channel because the dikes were not yet constructed in 

2008).........................................................................................................................................................15

Table 2. Dates and stages during Vicksburg bend multi-beam data collection.................................21

Table 3. Model simulation dates.............................................................................................................22

Table 4. Setup values in Vicksburg bend...............................................................................................49
MRG&P Report No. 33 x

Preface

This study was conducted for the US Army Corps of Engineers Vicksburg 

District, under Project Number 107202, “Mississippi River and Tributaries 

Project, Channel Improvement, Dikes Construction.” The technical 

monitor was Mrs. Viviana Berrios-Williamson.

The work was performed by the River and Estuarine Engineering Branch 

of the Flood and Storm Protection Division, U.S. Army Engineer Research 

and Development Center, Coastal and Hydraulics Laboratory (ERDCCHL). At the time of publication of this report, Mr. Keith W. Flowers was 

Branch Chief, and Dr. Cary A. Talbot was Division Chief. The Deputy 

Director of ERDC-CHL was Mr. Jeffrey R. Eckstein, and the Director was 

Dr. Ty V. Wamsley.

COL Teresa A. Schlosser was the Commander of ERDC, and the Director 

was Dr. David W. Pittman.
MRG&P Report No. 33 1

1 Introduction

1.1 Background

Navigation is a crucial mission of the US Army Corps of Engineers 

(USACE), and in recent years the navigation industry has expressed 

concern about difficulty in navigating through the two Vicksburg bridges

during periods of high flow. These concerns increased in January 2016 

when five allisions with the bridges in 9 days prompted the US Coast 

Guard to close navigation in the reach for towing vessels. The Vicksburg 

bridges are located at approximately river mile (RM) 435.7 above head of 

passes just downstream of a sharp bend as shown in Figure 1. Locations of 

the bridges and other relevant features within this study are also provided 

in Figure 1. The upstream bridge (US Highway 80) was constructed in 

1930, and a second bridge (Interstate 20 [I-20]) was constructed in 1973 

immediately downstream of the Highway 80 bridge with piers in line with 

the Highway 80 bridge piers to minimize impacts to navigation. Figure 2

shows the two bridges and the 800 feet (ft) navigation pass on the left 

center portion of the channel. The navigation charts for this reach and the 

bridges are included in Appendix A (USACE 2015).
MRG&P Report No. 33

2

Figure 1. Location map and relevant features. 
MRG&P Report No. 33 3

Figure 2. Navigation pass (upstream looking downstream). 

There are increased risk and difficulty in navigating this reach during high 

water conditions due to increased flow rates and velocity but also due to the 

navigation industry’s relative unfamiliarity with extreme high water 

conditions since these conditions occur infrequently and their duration is 

relatively short. The flood of record occurred during May of 2011 with stages 

on the Vicksburg gage reaching 57.1 ft and discharge measurements of 

2.3 million cubic feet per second (cfs) according to USACE river gages.

Stages have reached 50 ft five times since 2008 (2008, 2011, 2016, 2019, 

and 2020) and reached 49.9 ft in March of 2018. A 50 ft stage was only 

previously reached twice (1937 and 1973) in the time period of the current 

gage location, which dates back to 1935. During high water conditions in 

2016, the bridges were struck by tows five different times in 9 days while 

stages were between 49.15 ft and 50.10 ft. The possibility that the recent 

trend of more frequent high water events will continue coupled with the 

recent bridge allisions necessitates the investigation of navigation 

conditions in this reach during high water events.

A major concern of the navigation industry is the potential that the 

Marshall Brown Dikes on the left descending bank approximately 8 miles 

upstream of the bridges are negatively impacting navigation. These dikes 
MRG&P Report No. 33 4

were constructed in 2013 to replace the previously destroyed hardpoints 

that were flanked during the 2011 Flood. The recently constructed 

Marshall Brown Dikes’ locations are represented in Figure 3 by the four 

longer yellow lines labeled Dike 1, 2, 3, and 4. The shorter yellow lines 

labeled HP 1 through HP 12 represent the previous hardpoints, and 

existing revetment is outlined in red.

Figure 3. Marshall Brown Dikes (Dike 1, 2, 3, and 4). 

The hardpoints were constructed in 2010/2011 to help prevent and stop 

severe bank erosion that occurred between 2007 and 2009, likely during 

the 2008 flood. Figure 4 shows the evolution of the bankline at Brown’s

Point and the process that led to the Marshall Brown Dikes construction. 

In the image, the areas outlined in red are locations of ACM revetments, 

and the yellow lines are the locations of the hard points, which in this case 

are a good benchmark on the image to illustrate the movement of the 

bankline (Note: the yellow lines are just a reference in the first two images 

as they were only present during the 2012 image). The top image from 
MRG&P Report No. 33 5

2007 has the same tree/bankline as the earliest Google Earth image of the 

area in 1994 indicating a relatively stable bank from 1994 to 2007. Severe 

bank erosion is evident in the next image in 2009 with some areas 

receding as much as 500 ft. Because of the erosion, the hard points were 

constructed in 2010/2011 to help stabilize the bank. The third image from 

2012 is during an extreme low water event after the hardpoints were 

flanked and damaged during the 2011 Flood. The low water makes it 

somewhat difficult to compare the water’s edge, but the recession of the 

tree line can be observed. The Marshall Brown Dikes were later 

constructed in 2013 to replace the hardpoints in an attempt to prevent 

further migration of the bankline.
MRG&P Report No. 33 6

Figure 4. Marshall Brown bank retreat. 
MRG&P Report No. 33 7

The other dikes of focus in this study include hypothetical dikes near 

RM 437 whose proposed locations are shown with white lines in Figure 5. 

These dikes were recommended by the towing industry as a way to 

improve navigation conditions through the bridges with the idea that they 

will be able to prevent flow from cutting across the inside of the bend and 

force the flow to the outside of the bend, therefore preventing cross 

currents and allowing for a straighter flow path through the bridges. The 

dikes’ crests were modeled at a +17 LWRP (low water reference plane) 

resulting in a crest elevation of 66 ft. 

Figure 5. Proposed dikes’ locations. 

A third focus area of this study is the mat field or site where the ACM are 

cast and stored. In recent years, the site has experienced increased damage 

from flooding. The site begins flooding at approximately 43 ft on the 

Vicksburg gage. A level of 43 ft or higher has been reached on the 

Vicksburg gage 10 of the last 13 years from 2008 to 2020. Typical flood 

damage includes scour on the field, damaged mats, sediment and debris 

deposition, and flooded buildings. Clean up and repairs are time 
MRG&P Report No. 33 8

consuming and costly, and the flooding interrupts and delays the casting 

operations. Images of the mat field are shown in Figure 6. The top image is 

an on-site photo of the flooded mat field during high water conditions in 

early spring of 2018. On the bottom left, there is a photo of scour on the 

field and damaged mats that was taken after the water receded. The 

bottom right photo is an aerial image of the mat field flooded during high 

water conditions (no date provided).
MRG&P Report No. 33

9

Figure 6. Mat field flooding. 
MRG&P Report No. 33 10

1.2 Objective

The River and Estuarine Engineering Branch of the US Army Engineer 

Research and Development Center, Coastal and Hydraulics Laboratory 

(ERDC-CHL), conducted a two-dimensional (2D) numerical model study 

to investigate navigation conditions in the Mississippi River in the vicinity 

of the I-20 and Old Highway 80 bridges at Vicksburg, MS, for the USACE 

Vicksburg District (MVK). The main focus of the study was determining 

the impacts, if any, of the Marshall Brown Dikes at Brown’s Point located 

at river mile (RM) 444 approximately 8 miles upstream of the Vicksburg 

bridges. The study also consisted of testing proposed dikes along the right 

descending bank near RM 437, suggested by the towing industry to 

potentially improve navigation conditions, and a proposed levee to protect 

the articulated concrete mattress (ACM) casting field during flood stages. 

A location map is provided in Figure 1 illustrating these features and their 

relative locations.

1.3 Approach

This study was conducted using Adaptive Hydraulics Two-Dimensional 

Shallow Water Module (AdH-2DSW). Four recent high-water years, 

2008, 2011, 2016, and 2018, were simulated as validation tests and 

provided the opportunity to compare the model to field observations 

during these past floods. 

After the model validation (discussed in Chapter 3), an evaluation of 

Brown’s Point and the Marshall Brown Dikes was performed. To isolate 

the impact from the dikes, with and without dike conditions were 

simulated with the same flow conditions. A second evaluation of the 

Marshall Brown Dikes was attempted by simulating each year’s geometry 

with the same flow conditions and comparing the results. Each year’s 

geometry represented a time either before or after the construction of the 

dikes. These results are provided in Chapter 4.

Proposed scenarios were simulated in Chapter 5 to determine their 

potential impacts and feasibility. These scenarios included construction of 

proposed dikes along the right descending bank near RM 437, proposed 

construction of an earthen levee protecting the Delta Point mat casting 

field, and construction of the proposed dikes and proposed levee together.
MRG&P Report No. 33 11

2 Model Development

Adaptive Hydraulics (AdH) is a finite element code that was developed and 

is maintained at the ERDC-CHL. AdH consists of multiple modules which 

allow for simulation of a wide range of flow conditions. These modules 

include three-dimensional (3D) groundwater flow, 3D Navier-Stokes flow, 

3D shallow water flow, 2D overland flow, and 2D shallow water flow. AdH 

has the ability to dynamically refine temporal and spatial resolution along 

with the ability to simulate constituent transport (ERDC-CHL 2017). The 

2D shallow water module was used for this modeling effort. Although 2D, 

the inclusion of vorticity allows the model to account for the helical flow 

around bends illustrated by the image below (Figure 7) where the faster 

surface water is transported to the outside of the bend and the bottom water 

to the inside due to the conservation on mass. This correction allows a 

better representation of the 2D depth averaged velocity pattern, and the 

vorticity also allows for the computation of velocity at specific depths based 

off of the velocity profile associated with the vorticity. Initially in this study, 

vorticity was used to compute average velocities for the top 9 ft of the water 

column to represent the currents impacting towing vessels. Top 9 ft results 

are presented in the validation section and later in Appendix B. As the study 

progressed, depth averaged results were presented instead of the top 9 ft 

when investigating dike impacts due to concern with the applicability of the 

method of computing the top 9 ft velocity in capturing localized dike 

impacts to the water column.

Figure 7. Helical flow illustration in a river bend (ERDC-CHL 2017). 
MRG&P Report No. 33 12

2.1 Mesh development

All of the tested geometries for this study were developed from the same 

base 2D mesh. Mesh units are in feet and are projected in State Plane 

Coordinate System, Mississippi West with the vertical datum North 

American Vertical Datum of 1988 (NAVD88). The mesh domain consists 

of approximately 140 square miles and includes 30 miles of the Mississippi 

River and 17 miles of the Yazoo River. The mesh is bounded by the 

mainline Mississippi River levee to the west, a combination of the 

Mississippi River levee and the Yazoo backwater levee to the north, and 

natural high ground to the east. The model domain is outlined in red in 

Figure 8. Approximately 170,000 nodes and 340,000 elements make up 

the mesh with nodal spacing ranging from approximately 1,000 ft at the 

mesh boundary in the overbank to approximately 10 ft in areas where high 

resolution is needed to adequately capture the geometry. High levels of 

refinement are included in the base mesh at any location where dikes 

existed in any of the 4 years simulated and locations of the proposed dikes 

and levee. This allowed for the same mesh (node locations and element 

connectivity) to be utilized in all model simulations with appropriate 

bathymetry for each scenario. An example of the levels of mesh refinement 

including dikes and overbank just upstream of the Vicksburg bend is 

shown in Figure 9.

Figure 8. Model limits. 
MRG&P Report No. 33 13

Figure 9. Mesh resolution. 

Every element of the mesh is assigned a material type (Figure 10). Material 

types allow the specification of different parameters to different regions of 

the mesh. The main parameter that is assigned by material type is friction. 

AdH has the ability to invoke numerous friction options, but the two used in 

this model are Manning’s n (MNG), which is converted to effective 

roughness height and unsubmerged rigid vegetation (URV). URV was used 

in the overbank wooded areas of the model where the vegetation creates 

more drag as the water level rises. To simulate the URV friction, bed 

roughness height (k), average stem diameter, and average stem density 

(stems per unit area) must be specified. Table 1 includes all material types 

along with brief descriptions of the applied friction values that were utilized 

for the 2008 simulation as an example. For URV in the third column, the 

first number is bed roughness height (feet), the second number is diameter 

(feet) and the third number is density (unitless). Additional friction was 

applied in the model at all submerged dikes by invoking the submerged dike 

(SDK) card. The use of this card allows the model to better simulate the 

energy losses associated with the expansion of flow downstream of a dike or 

weir. The application of the SDK card and associated equations is presented 

in the AdH-2DSW User Manual and Brown (2017).
MRG&P Report No. 33 14

Figure 10. Material type locations. 
MRG&P Report No. 33 15

Table 1. Material types and friction for 2008 (Note: some dike material types are assigned the 

same roughness as the channel because the dikes were not yet constructed in 2008). 

Material Type Description 2008 Friction 

Mississippi Main Channel Mississippi River in-channel MNG 0.021

Overbank Timber Wooded areas in floodplain URV 0.02, 2, .1

Fields Crops and grass fields MNG 0.03

Island 1 Heavily vegetated large island URV 0.02, 1, .2

Island 2 Small island, increasing in size and vegetation MNG 0.035

Island 3 Medium island, Increasing size and vegetation MNG 0.035

All Years Dikes Dikes that are present in all simulated years MNG 0.04

Alternative Dikes Proposed dikes at Delta Point MNG 0.021

Yazoo River Yazoo River and port waterway MNG 0.021

Industrial Port of Vicksburg and Vicksburg waterfront MNG 0.035

Flooded Oxbow Mostly permanent ponded water in floodplain MNG 0.03

Mat Field Casting and housing field for ACM MNG 0.035

Overbank Scattered Timber Overbank areas with limited trees URV 0.025, 1, .05

Spur Dikes Dikes coming off of levees MNG 0.04

Mat Field Levee Proposed levee to protect mat field MNG 0.05

Marshall Brown Hard points System of small dikes constructed in 2010 MNG 0.021

Inflow Overbank Overbank at Mississippi River inflow boundary URV 0.02, 2, .1

Marshall Brown Dikes Four dike constructed in 2013 MNG 0.021

Inflow Channel Mississippi River channel at inflow boundary MNG 0.021

Elevation datasets were created for each year by combining single-beam 

cross-sectional data, multi-beam data, dike surveys, and lidar that were all 

provided by MVK. Overbank elevations for all years are represented by a 

2008 lidar dataset. This should be appropriate as the overbank elevations 

tend to adjust much slower than the in channel elevations. The Vicksburg 

bend between RM 441 and 435 is surveyed each year using multi-beam data 

providing complete coverage of the area of interest. Surveyed cross sections 

with approximately 1,000 ft spacing between consecutive cross sections 

were used for the remaining Mississippi River outside of the multi-beam 

coverage. Dike surveys were utilized to properly capture the geometry and 

location of the dikes. These sometimes consisted of multi-beam surveys and 

sometimes numerous single beam transects perpendicular to the 

orientation of the dikes. One set of single-beam cross-sectional data with 

100 ft spacing was available and was used for every year on the Yazoo River 
MRG&P Report No. 33 16

near the Port of Vicksburg. These data were also used to extrapolate down 

the Yazoo River to the confluence and up the Yazoo River to the inflow 

boundary for all years. The 2011 bathymetry data are shown in Figure 11 as 

an example. The thin lines that can be seen are the single beam data, and 

the large solid red area at the Vicksburg bend shows the extent of the multibeam data. The smaller patches of solid red are the multi-beam dike surveys 

while the disconnected stretch of red is the Yazoo cross sections. For each 

year, once the bathymetry datasets were carefully combined and 

triangulated, they were merged into the overbank lidar and then 

interpolated to the mesh. The final 2008, 2011, 2016, and 2018 mesh 

elevations are shown in Figure 12 through Figure 15 along with the dates 

and the stages during the time the multi-beam was collected in Table 2.

Figure 11. Bathymetry dataset. 
MRG&P Report No. 33 17

Figure 12. 2008 Mesh elevation. 
MRG&P Report No. 33 18

Figure 13. 2011 Mesh elevation. 
MRG&P Report No. 33 19

Figure 14. 2016 Mesh elevation. 
MRG&P Report No. 33 20

Figure 15. 2018 Mesh elevation. 
MRG&P Report No. 33 21

Table 2. Dates and stages during Vicksburg bend multi-beam data collection. 

Model Year Start Finish 

Minimum 

Stage 

Maximum 

Stage 

2008 15-Jun-07 12-Jul-07 19.04 19.08

2011 6-Jun-11 9-Jun-11 47.70 49.35

2016 8-Aug-15 18-Aug-15 24.39 39.10

2018 14-Jul-17 21-Jul-15 24.25 30.13

2.2 Boundary conditions

Discharge in the model is specified through a Mississippi River and a 

Yazoo River inflow boundary. In some cases, during high water conditions 

on the Mississippi River flow can back up resulting in flow in the upstream 

direction on the Yazoo River (out of the model). In these cases, the 

discharge is specified as negative, and water is removed from the model at 

the Yazoo River boundary. The inflows to the Yazoo River were specified 

using United States Geological Survey (USGS) daily discharge gage data. 

USGS 07288800 Yazoo River at Redwood, MS, was used for 2011, 2016, 

and 2018, but data were unavailable for 2008, so USGS 07288955 Yazoo 

River BL Steele Bayou NR Long Lake, MS, was used for 2008. Inflows for 

the Mississippi River were assigned based on the USGS gage at Vicksburg, 

USGS 07289000 Mississippi River at Vicksburg, MS. 

Since the measured flow passing by the Vicksburg gage included flow from 

the Yazoo tributary, the differences between the Vicksburg gage and the 

Yazoo gage were used to determine the inputs at the upstream Mississippi 

River boundary. It was also determined that a 12-hour travel lag time was 

appropriate due to applying the Vicksburg, MS, measurements at a 

location farther upstream of the observations. This offset was needed to 

match the timing of the hydrograph at the Vicksburg gage shown in a 

subsequent validation section. 

The downstream control of the model is a tail water boundary condition 

where water surface elevations are specified at the downstream end of the 

model on the Mississippi River. Water surface elevations were interpolated 

between the Vicksburg USACE gage and the next USACE gage 70 miles 

downstream at Natchez, MS. This method assumes a constant slope 

between the two gages, which is unrealistic, so 0.2 ft was added to the 

interpolated values to produce better fitting slopes and water surface 

elevation profiles. This increase in stages was verified with an existing 
MRG&P Report No. 33 22

one-dimensional model of the Lower Mississippi River, and analysis of the 

resulting water surface elevation profiles reinforced this decision. Table 3

includes the dates that were simulated as the peak flood for each year, 

including the time before and after each extreme event. 

Table 3. Model simulation dates. 

Year Dates 

2008 April 3 - May 3

2011 May 1 - May 31

2016 January 1 -January 31

2018 March 5 - April 4

Inflow and tail water hydrographs for all years are presented in Figure 16-

18. Model time is used on the x-axis instead of dates to allow all years to be 

plotted together.

Figure 16. Mississippi River inflow hydrographs. 
MRG&P Report No. 33 23

Figure 17. Yazoo River inflow hydrographs. 

Figure 18. Downstream stage hydrographs. 
MRG&P Report No. 33 24

3 Validation to Past Floods

With multiple flood events in recent years, there are abundant data 

available to test model performance during these extreme events. The 

USACE gage and the USGS gage at Vicksburg provide continuous 

measured stage and predicted discharge data available for all of the 

simulated time periods. Modeled flows and stages were compared to the 

gage data for all four simulated years. MVK provided measured water 

surface profiles during the floods for 2008, 2011, and 2016 to utilize in the 

model validation. Acoustic Doppler Current Profiler (ADCP) data are also 

collected in the area on a regular basis to measure discharge. Discharge 

measurements are made multiple times each year and up to every day 

during some flood events. However, these measurements are collected 

below the bridges at approximately RM 435 and do not provide valuable 

insight into the conditions above the bridge where the navigation issues 

persist. In 2008, a large data collection effort was focused on navigation in 

this reach just upstream of the bridge. The effort included measuring 

velocity data upstream of the bridge with ADCP measurements and 

deploying and tracking floats through the river reach. This provided great 

insight and data in the area of concern to use in the model validation. The 

following sections include each year to focus on the available data collected 

and compare that data to the model results.

3.1 2008 

For the 2008 flood, the model simulates April 3 to May 3, which includes 

the crest on April 20. During this time, ERDC was involved with a 

predecessor project investigating navigation conditions in this reach of the 

river. The data collection effort for that study included two trips. The first 

trip on April 9 included measuring ADCP transects throughout the reach 

upstream of the bridge (Figure 19), and the second trip consisted of a 

drogue study on May 1. The drogue study involved releasing two floats and 

tracking them via Global Positioning System (GPS). Each drogue consisted 

of a 1 ft diameter buoy above a section of right angle vanes approximately 

7 ft long (Figure 20.) The assembled floats had a 9 ft draft, intended to 

represent the flow impacting a tow with an equivalent draft, and were 

equipped with GPS receivers logging location data every 3 seconds. 
MRG&P Report No. 33 25

Figure 19. April 9, 2008 transect locations. 

Figure 20. Drogue. 
MRG&P Report No. 33 26

MVK provided a water surface elevation profile that was measured April 

21. This along with the Vicksburg gage was used to compare water levels 

between the model and the field. Model discharge was also compared to 

the gage data. 

3.1.1 2008 velocity comparisons

Comparisons between the model and measured field data for the velocity 

transects collected April 9 are presented in plan view comparisons and 

cross-sectional comparisons for each transect. Velocities at Transects 2 

through 16 for depth averaged and the top 9 ft averaged are compared in 

Figure 21 and Figure 22, respectively. Model velocities are shown in the 

left image of the figures while measured ADCP is in the middle image. The 

right image includes model and measured velocity vectors overlaid on each 

other with the model in black and the ADCP in red. Plan views of transects 

121, 22, 20, and 18 are shown in Figure 23 and 24. The top 9 ft velocity is 

predicted by using an estimated vertical velocity profile corresponding to 

the amount of vorticity in the bend.

The second method of comparing the transects as cross-sectional plots can 

be found in Figure 25 to Figure 36. All cross sections in this report are 

plotted with an upstream perspective with left descending bank on the left 

and right descending bank on the right. In each figure, the top chart plots 

the depth in the model and the depth measured by the ADCP. The 

difference in this plot illustrates the variability in the bathymetry between 

the flood event and the data collection time. The middle plot shows the 

depth averaged velocity for the model and the ADCP, and the bottom 

figure represents the unit discharge which is the product of both the depth 

and velocity. This is a representation of the flow distribution in the 

channel. The unit discharge comparisons attempt to rectify the 

discrepancies that are sometimes observed between the simulated 

elevations and the elevations observed during the flood event. Transect 2 

is downstream of the bridge and captures the localized shadowing impact 

of the bridge piers.
MRG&P Report No. 33 27

Figure 21. April 9, 2008 depth averaged velocity plan view comparison for Transects 2, 4, 6, 

8, 10, 12, 14, and 16 (modeled on left, measured in middle, both on right). 

Figure 22. April 9, 2008 top 9 ft velocity plan view comparison for Transects 2, 4, 6, 8, 10, 

12, 14, and 16 (modeled on left, measured in middle, both on right). 
MRG&P Report No. 33 28

Figure 23. April 9, 2008 depth averaged velocity plan view comparison for Transects 121, 22, 

20, and 18 (modeled on top and measured on bottom). 
MRG&P Report No. 33 29

Figure 24. April 9, 2008 top 9 ft velocity plan view comparison for Transects 22, 20, and 18 

(modeled on top and measured on bottom). 
MRG&P Report No. 33 30

Figure 25. 2008 Transect 121 depth, velocity, and unit discharge comparisons. 
MRG&P Report No. 33 31

Figure 26. 2008 Transect 22 depth, velocity, and unit discharge comparisons. 
MRG&P Report No. 33 32

Figure 27. 2008 Transect 20 depth, velocity, and unit discharge comparisons. 
MRG&P Report No. 33 33

Figure 28. 2008 Transect 18 depth, velocity, and unit discharge comparisons. 
MRG&P Report No. 33 34

Figure 29. 2008 Transect 16 depth, velocity, and unit discharge comparisons. 
MRG&P Report No. 33 35

Figure 30. 2008 Transect 14 depth, velocity, and unit discharge comparisons. 
MRG&P Report No. 33 36

Figure 31. 2008 Transect 12 depth, velocity, and unit discharge comparisons. 
MRG&P Report No. 33 37

Figure 32. 2008 Transect 10 depth, velocity, and unit discharge comparisons. 
MRG&P Report No. 33 38

Figure 33. 2008 Transect 8 depth, velocity, and unit discharge comparisons. 
MRG&P Report No. 33 39

Figure 34. 2008 Transect 6 depth, velocity, and unit discharge comparisons. 
MRG&P Report No. 33 40

Figure 35. 2008 Transect 4 depth, velocity, and unit discharge comparisons. 
MRG&P Report No. 33 41

Figure 36. 2008 Transect 2 depth, velocity, and unit discharge comparisons. 
MRG&P Report No. 33 42

ADCP data were also collected upstream of the bridge during the second 

trip on May 1. The boat that was dropping and following the drogues was 

also collecting ADCP. Comparisons to this ADCP data are in Figure 37. 

Model velocity magnitude and vectors are in the left image while 

boat-measured velocity magnitudes are in the center image. The right 

image includes velocity vectors from the model in black and the measured 

velocity vectors overlaid in red. Drogue paths from the trip are shown in 

the left side of Figure 38 along with modeled flow tracer paths on the right 

side of the image. These modeled tracer paths can be used as a qualitative 

comparison with the float paths.

Figure 37. May 1, 2008 ADCP velocity comparisons. 

 
MRG&P Report No. 33 43

Figure 38. Drogue paths (left image is observations and right image is model results). 
MRG&P Report No. 33 44

3.1.2 2008 gage and water surface elevations comparisons

Since the gage data were used to assign boundary conditions, comparing 

back to this data is more of a check on the timing of the hydrograph than a 

true validation comparison. Comparisons of water levels and discharge 

between the model and the gage data are shown in Figure 39 and 40. 

Water levels are also compared to a water surface elevation profile that 

was measured on April 21, 2008. The location of the profile is mapped in 

Figure 41, and the comparison is shown in Figure 42. Approximate river 

miles are plotted on the x-axis. The distance is based on the distance 

traveled by the boat and not true river miles with an adjustment to ensure 

the river mile of the bridge (RM 435.7) was consistent. Therefore, these 

are approximate values with an increasing uncertainty progressing away 

from the bridges. This is the case for all water surface profiles in this 

report that are plotted vs, approximate river mile.

Figure 39. 2008 stage comparison with USACE gage. 

Figure 40. 2008 total discharge comparison with USGS gage. 
MRG&P Report No. 33 45

Figure 41. 2008 water surface elevation profile location. 

Figure 42. April 21, 2008, water surface elevation profile comparison. 
MRG&P Report No. 33 46

Year 2008 provided a substantial amount of data to use to validate the 

model. Velocities compare well throughout the reach, qualitatively and 

quantitatively. Vector directions follow the same patterns as the measured 

data, and the flow traces follow similar paths to the floats in the drogue 

study. Flow distributions and velocity magnitudes compare well with the 

measured transects. Some of the upstream transects, especially 20 and 22, 

illustrate the model’s ability to capture the impact of the dikes and the 

islands in the dike field as flow is redistributed into the channel. Profiles 

closer to the bridge had differences in bathymetry elevations between the 

surveyed multi-beam used in the model and the dates the ADCP were 

collected which impact velocities, but the model did adequately replicate 

the field and captured the observed flow distributions. 

The water surface profile diverges some at the upstream end with it being 

a foot high in some areas, but in the area of concern it accurately replicates 

the observations.

3.2 2011

May 1 to May 31 was simulated for 2011. Gage comparisons of stage and 

discharge are shown in Figure 43 and 44, respectively. Water surface 

elevation profiles were measured on three different dates during the 

simulated period. Profile 1 was measured May 18 from approximately RM 

490 to RM 447. Profile 2 was measured May 19 on the Yazoo River from 

the confluence with the Mississippi River to almost 50 miles upstream. 

Profile 3 was measured May 20 and includes RM 447 to 420. Locations of 

the three profiles are shown in Figure 45, and the comparisons are plotted 

in Figures 46-48. Measured setup or difference in elevation across the 

channel from the inside of the bend to the outside was measured in the 

Vicksburg bend during the 2011 Flood and was reported in Jones et al. 

(2018). These measured values are shown in Table 4 along with the 

differences in elevation produced by the model.
MRG&P Report No. 33 47

Figure 43. 2011 stage comparison with USACE gage. 

Figure 44. 2011 total discharge comparison with USGS gage. 
MRG&P Report No. 33 48

Figure 45. 2011 water surface elevation profile locations. 

Figure 46. May 18, 2011, Profile 1 water surface elevation comparison. 
MRG&P Report No. 33 49

Figure 47. May 19, 2011, Profile 2 water surface elevation comparison. 

Figure 48. May 20, 2011, Profile 3 water surface elevation comparison. 

Table 4. Setup values in Vicksburg bend. 

Location 

River 

Mile 

May 13, 2011, Setup May 16, 2011, Setup 

Measured Model Measured Model 

In bend 438 0.84 ft 0.88 ft 1.1 ft 0.95 ft

Upstream bridge 436 0.64 ft 0.51 ft 0.74 ft 0.54 ft

Downstream bridge 435.5 0.83 ft 0.98 ft 0.86 ft 1.04 ft
MRG&P Report No. 33 50

The 2011 event was a much higher flood than 2008, but water levels still 

matched reasonably well. The gage comparisons confirm that the timing of 

the flows is accurate. Once again, water levels at the upstream end of the 

model were approximately 1 ft higher, but the profile through the bridge 

shows that the model is able to replicate the general slope trends that were 

measured in the study area. The model is also able to replicate the 

dynamics around the bend with all setup values being within 0.2 ft of the 

measured differences.

3.3 2016

Winter flood conditions from January 1, 2016, to January 31, 2016, were 

simulated to represent the 2016 Flood. Stage and discharge are compared 

to the gage data throughout the entire run in Figure 49 and 50, 

respectively. One water surface profile was measured during this 

simulated period and is shown in Figure 51 with comparisons between 

model and field in Figure 52.

Figure 49. 2016 stage comparison with USACE gage. 
MRG&P Report No. 33 51

Figure 50. 2016 total discharge comparison with USGS gage. 

Figure 51. 2016 water surface elevation profile location. 
MRG&P Report No. 33 52

Figure 52. January 17, 2016, water surface elevation profile comparison. 

The water surface elevation profile for the model is somewhat low at the 

upstream extents of the profile but does replicate the behavior in the 

vicinity of the bridge.

3.4 2018

March 5 – April 4 was simulated for the most recent event (2018). Water 

surface elevation and discharge are compared to the gage data (Figure 53

and 54, respectively), but no water surface profile data were available at 

the time resulting in limited data for model-to-field comparisons for this 

particular event.

Figure 53. 2018 stage comparison with USACE gage. 
MRG&P Report No. 33 53

Figure 54. 2018 total discharge comparison with USGS gage. 
MRG&P Report No. 33 54

4 Evaluation of Marshall Brown Dikes

To evaluate the hydraulic impacts from the Marshall Brown Dikes, the same 

flows were used to simulate conditions for the with dikes (2018 conditions) 

and a hypothetical without dikes (2018 conditions with the dikes removed) 

in Section 4.1. A second phase of modeling was also performed to 

investigate the hydraulic impacts of morphological changes since the 

construction of the Marshall Brown Dikes as detailed in Section 4.2. 

4.1 With and without Marshall Brown Dikes

The 2018 mesh which contains the Marshall Brown Dikes represents the 

with dike condition. The without dike condition was created by removing 

the dikes and smoothing the bathymetry in the area of the removed dikes. 

Both the with and without dikes geometries are shown side by side in 

Figure 55 (remaining portions of the mesh were equivalent between 

simulations). 

A high, medium, and low flow were simulated to determine the impacts 

across a range of flow conditions. The simulated high flow represents 

conditions when approximately 50 ft is reached on the Vicksburg gage or an 

elevation of 96.13 ft NAVD88. The Vicksburg gage is referenced to a gage

zero of 46.23 ft National Geodetic Vertical Datum of 1929 (NGVD29), and a 

conversion of -0.1 ft was used to convert from NGVD29 to NAVD88 at 

Vicksburg. The boundary condition for this run included a Mississippi River 

flow of 1.8 million cfs, no flow at the Yazoo River boundary, and a tail-water 

elevation of 94.73 ft. No flow through the Yazoo River is reasonable at this 

high of a stage since water typically backs up the Yazoo River until the flood 

recedes. A stage of 25 ft (elevation 71.13) was determined to be an 

approximate average stage on the Vicksburg gage over the last 10 years. 

Using measured discharge data from the past few years plotted verse stage, 

this stage translated to a flow of approximately 650,000 cfs and was used as 

the medium flow. The low flow was determined by using the water surface 

elevation of 47.6 ft NAVD88 from the 2007 low water reference plane,

which corresponds to a flow rate of 240,000 cfs. During the high flow, the 

Marshall Brown Dikes are approximately 35 ft underwater, and they are 

submerged approximately 10 ft during the medium flow. During the low 

flow, the dikes are mostly emergent structures with just the tips of the dikes 

extending into the water. 
MRG&P Report No. 33 55

Figure 55. Mesh elevations for without and with Marshall 

Brown Dikes. 

4.1.1 High flow for with and without Marshall Brown Dikes

The high flow of 1.8 million cfs was simulated using both geometries, and 

velocities are shown in Figure 56 for the with dikes and without dikes.

Viewing these two plots side by side makes it difficult to see the 

differences, so a difference of the two velocity sets was calculated to better 

show the velocity impacts due to the Marshall Brown Dikes (Figure 57). 

The 2018 velocities (with dikes) were subtracted from the simulation with 

the dikes removed, so contours of reddish tint represent areas where the 

without dikes velocity is higher. This image shows that the dikes force 

water to the outside of the bend as expected and increase velocities along 

the right descending bank near the dikes. However, the lightest shades of 

blue and yellow only represent differences of 0.01 to 0.1 ft per sec, so the 

differences in the vicinity of the bridges are negligible.
MRG&P Report No. 33 56

Figure 56. High flow velocities for 2018 (with dikes – left, without dikes - right). 
MRG&P Report No. 33 57

Figure 57. High flow velocity difference for with and without Marshall Brown Dikes 

(2018 dikes removed minus 2018). 

Five new transects were created (Figure 58), and velocities were extracted 

from the model in these locations and plotted as a second way to view the 

velocity differences. Velocities for both conditions are plotted at each 

transect in Figure 59 through 63. Velocities for both conditions at all five 

locations are nearly identical (blue line is directly behind dashed orange

line) and reinforce the spatial plot observations that the impact this far 

downstream from the dikes is negligible.
MRG&P Report No. 33 58

Figure 58. Velocity comparison transect locations. 

Figure 59. With (2018) and without (2018 dikes removed) Marshall Brown Dikes Transect 1 

velocity comparison for high flow. 
MRG&P Report No. 33 59

Figure 60. With (2018) and without (2018 dikes removed) Marshall Brown Dikes Transect 2 

velocity comparison for high flow. 

Figure 61. With (2018) and without (2018 dikes removed) Marshall Brown Dikes Transect 3 

velocity comparison for high flow. 
MRG&P Report No. 33 60

Figure 62. With (2018) and without (2018 dikes removed) Marshall Brown Dikes Transect 4 

velocity comparison for high flow. 

Figure 63. With (2018) and without (2018 dikes removed) Marshall Brown Dikes Transect 5 

velocity comparison for high flow. 

Impacts of the dikes on water levels were also examined. Two profiles were 

used to compare water levels and longitudinal slopes. Profile 1 starts at 

approximately RM 449 and extends to the downstream boundary of the 

mesh near RM 429. Profile 2 consists of a shorter portion of the first 

profile near the bridge and allows a better visual comparison of the water 

surface slopes in the vicinity of the bridge. Locations of these two profiles 
MRG&P Report No. 33 61

are mapped in Figure 64. Figure 65 maps the water surface elevation and 

shows the extent of flooding for the high flow on the base 2018 mesh (with 

dikes results). Water surface elevations for both scenarios are compared in 

Figure 66 and 67. Figure 66 shows the dikes produce a slight increase in 

water levels upstream of RM 443, which is just below the location of the 

dikes. This increase is only a couple of inches and would likely be 

eliminated as the bed of the river reacts to the construction of the dikes. 

Similar to the velocities, the water levels for profile 2 in Figure 67 show a 

negligible impact in the vicinity of the bridge. 

Figure 64. With (2018) and without (2018 dikes removed) Marshall Brown Dikes Water 

surface elevation profile comparison locations. 
MRG&P Report No. 33 62

Figure 65. 2018 high flow water surface elevation. 
MRG&P Report No. 33 63

Figure 66. With (2018) and without (2018 dikes removed) Marshall Brown Dikes water 

surface elevation Profile 1 comparison for high flow. 

Figure 67. With (2018) and without (2018 dikes removed) Marshall Brown Dikes water 

surface elevation Profile 2 comparison for high flow. 
MRG&P Report No. 33 64

4.1.2 Medium flow for with and without Marshall Brown Dikes

The medium flow comparisons were performed using the same method as 

the high flow and resulted in similar trends and comparisons. The 

difference plot (Figure 68) shows the dikes increasing the velocities down 

the right bank, but in this case, the impact does not extend as far 

downstream as the high flow. The difference at the bridge is less than 

.01 foot per second (fps). The five velocity transects support this with both 

scenarios matching up almost exactly to the point where the blue line (with 

dikes) cannot be distinguished from orange (without dikes) (Figures 69-73).

Figure 68. Medium flow velocity difference for with and without Marshall Brown Dikes 

(2018 dikes removed minus 2018) . 
MRG&P Report No. 33 65

Figure 69. With (2018) and without (2018 dikes removed) Marshall Brown Dikes Transect 1 

velocity comparison for medium flow. 

Figure 70. With (2018) and without (2018 dikes removed) Marshall Brown Dikes Transect 2 

velocity comparison for medium flow. 
MRG&P Report No. 33 66

Figure 71. With (2018) and without (2018 dikes removed) Marshall Brown Dikes Transect 3 

velocity comparison for medium flow. 

Figure 72. With (2018) and without (2018 dikes removed) Marshall Brown Dikes Transect 4 

velocity comparison for medium flow. 
MRG&P Report No. 33 67

Figure 73. With (2018) and without (2018 dikes removed) Marshall Brown Dikes Transect 5 

velocity comparison for medium flow. 

Water surface elevation comparisons showed the same minimal difference 

between the with and without dikes. Figure 74 includes a map of the water 

surface elevation during the medium flow for the base condition (with 

dikes). Unlike the high flow, all of the flow is below top bank and within 

the channel. Figures 75 and 76 plot the water surface elevation at profile 1 

and 2, respectively.

Figure 74. 2018 medium flow water surface elevation. 
MRG&P Report No. 33 68

Figure 75. With (2018) and without (2018 dikes removed) Marshall Brown Dikes water 

surface elevation Profile 1 comparison for medium flow. 

Figure 76. With (2018) and without (2018 dikes removed) Marshall Brown Dikes water 

surface elevation Profile 2 comparison for medium flow. 
MRG&P Report No. 33 69

4.1.3 Low flow for with and without Marshall Brown Dikes

The low flow simulation of 240,000 cfs was conducted using the same 

approach as the high and medium flow. Low flow results followed the 

same trend set by the previous two flows. A further reduction in flow 

continued to reduce the impact of the dikes. There is negligible difference 

in velocities at the bridge and at this low of a flow rate the extent of the 

dike impacts are reduced to within 2 miles downstream of the dikes 

(Figure 77). The velocity transects in Figures 78-82 are nearly identical for 

the with and without dikes scenarios. For transects 4 and 5, velocities on 

the right side of the transects are zero because flow is confined to a 

narrower channel as the bars on the right bank become emergent as the 

stages drop. 

Figure 77. High flow velocity difference for with and without Marshall Brown Dikes 

(2018 dikes removed minus 2018). 
MRG&P Report No. 33 70

Figure 78. With (2018) and without (2018 dikes removed) Marshall Brown Dikes Transect 1 

velocity comparison for low flow. 

Figure 79. With (2018) and without (2018 dikes removed) Marshall Brown Dikes Transect 2 

velocity comparison for low flow. 
MRG&P Report No. 33 71

Figure 80. With (2018) and without (2018 dikes removed) Marshall Brown Dikes Transect 3 

velocity comparison for low flow. 

Figure 81. With (2018) and without (2018 dikes removed) Marshall Brown Dikes Transect 4 

velocity comparison for low flow. 
MRG&P Report No. 33 72

Figure 82. With (2018) and without (2018 dikes removed) Marshall Brown Dikes Transect 5 

velocity comparison for low flow. 

The low flow water surface elevation can be seen in Figure 83. Similar to 

the medium flow, all flow is in the channel, but in this case the water levels 

are much lower and bars are exposed throughout the reach. The water’s 

edge is very similar to the background image as sand bars can be seen in 

the areas of the channel with no contoured depth values. Like the medium 

and high flow, a slight difference of water levels can be seen in the 

immediate vicinity of the dikes in Figure 84, but no noticeable difference 

closer to the bridge (Figure 85). A gap exists in Profile 1 between RM 447 

and 445. This is due to the profile in Figure 64 being outside the extent of

the water during the low flow.
MRG&P Report No. 33 73

Figure 83. 2018 low flow water surface elevation. 
MRG&P Report No. 33 74

Figure 84. With (2018) and without (2018 dikes removed) Marshall Brown Dikes Water 

surface elevation Profile 1 comparison for low flow. 

Figure 85. With (2018) and without (2018 dikes removed) Marshall Brown Dikes Water 

surface elevation Profile 2 comparison for low flow. 
MRG&P Report No. 33 75

Overall, the results from the with and without Marshall Brown Dikes 

section support the idea that the geometry of the dikes has a local impact 

but is negligible downstream near the bridge. This evaluation is only 

looking at the changes to hydraulics caused by the dike geometry and does 

not include possible geomorphic changes due to the dikes.

4.2 Evaluation of the impact of the Marshall Brown Dikes with 

geomorphic changes 

As discussed in the background section, Brown’s Point has gone through 

a transformation in the last decade (2008-2018). Each of the four 

simulated years represents a period in that evolution. 2008 is before any 

hard points or dikes were constructed while 2011 is after the natural 

channel widening and later installation of the hard points. Years 2016 

and 2018 represent conditions after the construction of the existing 

Marshall Brown Dikes. The bathymetry for each of these years was 

simulated with the high flow boundary conditions to determine how this 

channel evolution and geomorphic changes impact velocities. If there 

was a significant change in morphology due to the implementation of 

these dikes, it would be evident in the bathymetry, and if these 

bathymetry changes were drastic enough to significantly impact 

velocities, the impact would be captured with these simulations. 

Velocities for each year’s geometry are shown in Figures 86-89. Difference 

plots referenced to 2018 for the three previous years show the changes 

from each year to current conditions in Figures 90-92. Positive values 

represent areas where current conditions (2018) have higher velocities 

than the prior years. Figures 93-95 track how the velocity patterns change 

through time. The three figures are ordered in a manner to show the 

difference between each subsequent year with positive values representing 

an increase in velocity from the prior year to the next year. Figure 93

shows the difference in velocity from 2008 to 2011; Figure 94 is 2011 to 

2016; and Figure 95 is 2016 to 2018.
MRG&P Report No. 33 76

Figure 86. High flow velocities for 2008. 
MRG&P Report No. 33 77

Figure 87. High flow velocities for 2011. 
MRG&P Report No. 33 78

Figure 88. High flow velocities for 2016. 
MRG&P Report No. 33 79

Figure 89. High flow velocities for 2018. 
MRG&P Report No. 33 80

Figure 90. High flow velocity differences 2008 to 2018 (2018 minus 2008). 
MRG&P Report No. 33 81

Figure 91. High flow velocity differences 2011 to 2018 (2018 minus 2011). 
MRG&P Report No. 33 82

Figure 92. High flow velocity differences 2016 to 2018 (2018 minus 2016). 
MRG&P Report No. 33 83

Figure 93. Difference in velocities from 2008 to 2011 (2011 minus 2008). 
MRG&P Report No. 33 84

Figure 94. Difference in velocities from 2011 to 2016 (2016 minus 2011). 
MRG&P Report No. 33 85

Figure 95. Difference in velocities from 2016 to 2018 (2018 minus 2016). 

All of these previous figures show the variation in velocity across years. 

Most of the changes are within 0.5 fps with some smaller areas of up to 

2 fps. Most of the changes appear to be driven by general bathymetry 

changes such as an evolution of dunes or local areas of aggradation and 

degradation. In Figure 94 (2011 to 2016), the dikes impact shown in the 

previous section can be observed as there are higher velocities in the 

outside of the bend and lower velocities on the inside where the dikes are 

located at Brown’s point. In this image, there is also an increase in 

velocities in the bend just upstream of the bridge. This is due to lower 

velocities in 2011 as a result of a deeper channel in this area. The 

bathymetry in this location for 2011 is from a survey that was conducted 

post 2011 Flood, which is the flood of record and likely significantly 
MRG&P Report No. 33 86

scoured the channel in this location. This is an example of how the 

varying bathymetry throughout the course of a year created by varying 

flow conditions makes this a difficult comparison as each year’s 

bathymetry only represents a snapshot in time.

Velocities were also extracted from the model in the locations of the five 

new transects shown in Figure 58 in the previous subsection and are 

plotted for each year to compare cross-sectional velocity profiles. 

Velocities for all years are plotted at each transect in Figure 96 through 

Figure 100. 

Figure 96. Transect 1 multi-year comparison. 

Figure 97. Transect 2 multi-year comparison. 
MRG&P Report No. 33 87

Figure 98. Transect 3 multi-year comparison. 

Figure 99. Transect 4 multi-year comparison. 

Figure 100. Transect 5 multi-year comparison. 
MRG&P Report No. 33 88

Similarly to the velocity difference plots, the profiles show slightly varying 

results across years. The largest differences produced in the profiles are 

approximately 2 fps and are often a result of the lower velocities during the 

simulation of the 2011 bathymetry. For all profiles, 2008 fits more in line 

with the post dike construction years of 2016 and 2018 than 2011, and 

2008 has higher velocities for Profile 2, 3, and 4.

Water surface elevations were also compared across years using the 

profiles from Figure 64 in the previous section. Profiles 1 and 2 are shown 

in Figures 101 and 102, respectively.

Figure 101. Multi-year water surface elevation Profile 1 comparison. 
MRG&P Report No. 33 89

Figure 102. Multi-year water surface elevation Profile 2 comparison. 

Water surface elevations produce the same conclusion as the velocity. 

There is variation across years due to bathymetry differences, but there is 

no conclusive evidence that these differences are due to the dikes any more 

than just general expected variations in bathymetry.
MRG&P Report No. 33 90

5 Proposed Alternatives

Three proposed alternatives to help improve river conditions were also 

simulated to determine their potential impacts to navigation conditions 

through the Vicksburg bridge reach. These alternatives consisted of the 

construction of new dikes, construction of an earthen levee, and a 

combination of the construction of the dikes and levee. The dikes were 

proposed by the navigation industry as an effort to improve navigation 

through the bridge by forcing the currents to the outside of the bend and 

preventing cross currents that push the tows towards the left descending 

bank. One negative impact these dikes may have is blocking the low water 

access channel to the ACM field and restricting access for barges to load 

the concrete mats. The second alternative is a proposed levee to help 

reduce damage to the ACM casting field during high water conditions. 

Building a ring levee would require a pumping system, some other method 

to drain the water from the inside, or a high enough crest elevation to 

prevent overtopping. Both options would likely have a significant cost 

associated with them, so a small earthen levee was proposed. The levee 

footprint was designed to connect to the main stem levee and run along 

the northern side of the mat field. This would prevent water from entering 

from upstream but still allow water to back up from farther downstream 

where stages would be lower. The levee alternative was tested to determine 

its impact to water levels and velocities over the mat field and also if it 

would have significant impacts to navigation. Alternatives that included 

the levee were only tested for the high flow as it is the only flow that 

produced high enough stages for the levee to have an impact. The three 

proposed alternatives are summarized below and locations, and elevations 

of the dikes and levees are mapped in Figure 103. 

• Proposed Dikes — three dikes with crest elevations of 66 ft NAVD88, 

17 ft above the low water reference plane. The dikes are submerged by 

30 ft during the high flow, 5 ft during medium flow, and emergent by 

15 ft during the low flow. 

• Proposed Levee — levee with a 97.5 ft NAVD88 crest from the mainline 

levee to natural high ground. 

• Proposed Dikes and Levee.
MRG&P Report No. 33 91

Figure 103. Proposed dikes and levee. 

5.1.1 High flow

Velocities for the existing conditions (2018) and the alternative dikes are 

shown in Figure 104 along with a difference plot of the results. The 

difference plot was calculated by subtracting the 2018 velocities from the 

Dikes Alternative velocities. Positive values or reddish contours are areas 

where the dikes increased velocities and vice versa for blue. Unlike the 

Marshall Brown Dikes, the alternative dikes’ close proximity to the bridge 

create significant changes to the velocity in the bridge approach. The dikes 

force more flow to the outside of the bend therefore reducing the velocities 

on the inside bend and increasing velocities on the outside. 
MRG&P Report No. 33 92

Figure 104. High flow alternative velocity (2018 existing – left; alternative dikes – middle; alternative dikes minus 2018 existing – right) 
MRG&P Report No. 33 93

The following velocity profiles in Figures 105 to 109 provide a good 

illustration of the redistribution of flow that the dikes create. These plots 

also include profiles from the alternative levee and the alternative with the 

dikes and the levee. The levee has minimal impact on the velocities in the 

channel, so the 2018 alternative levee profile falls directly in line with the 

2018 base conditions, and the 2018 alternative dikes and levee is similar to 

the 2018 alternative dikes. The minimal impact of the levee on the velocities 

in the channel is also presented in Figure 110. In this figure, the image on 

the right shows the difference in velocities between the existing conditions 

and the levee alternative. The red-shaded contours represent areas where 

the levee creates higher velocities and the blue contours represent areas of 

lower velocities. There is a 1-2 fps reduction in velocities over the mat field,

and velocities in the main channel increase less than 0.05 fps. 

Figure 105. Transect 1 alternatives velocity comparison for high flow. 
MRG&P Report No. 33 94

Figure 106. Transect 2 alternatives velocity comparison for high flow. 

Figure 107. Transect 3 alternatives velocity comparison for high flow. 
MRG&P Report No. 33 95

Figure 108. Transect 4 alternatives velocity comparison for high flow. 

Figure 109. Transect 5 alternatives velocity comparison for high flow. 

 
MRG&P Report No. 33 96

Figure 110. High flow alternative velocity (2018 existing – left; alternative levee – middle; alternative levee minus 2018 existing – right). 
MRG&P Report No. 33 97

The introduction of the alternative dikes impacted the water levels 

throughout the reach. Water levels are plotted for Profile 1 and Profile 2 in 

Figures 111 and 112. Like the velocity profiles, there only appears to be two 

lines as the levee does not significantly impact the water levels in the 

channel. Year 2018 is directly behind the yellow alternative levee line and 

the alternative dikes is in line with the orange line, representing the 

alternative dikes and levee. Increases in velocity produced lower water 

levels downstream of the dikes to just below the bridge, but stages 

increased upstream of the dikes, and the increase extended all the way up 

to the boundary. These changes are all less than 0.3 ft and would likely be 

offset in a moveable bed model or a real-world scenario as the main 

channel scours and deepens in response to the dikes.

Figure 111. Alternatives water surface elevation Profile 1 comparison for high flow. 
MRG&P Report No. 33 98

Figure 112. Alternatives water surface elevation Profile 2 comparison for high flow. 

Along with reducing velocities across the mat field, the alternative levee 

also reduced depths over the mat field during the high flow event. To 

determine the levee’s impact, a difference was calculated between the 

water surface elevation for the levee alternative and the base 2018 

condition. Figure 113 maps the water surface elevation differences and 

shows an outline of the ACM field. Blue contours and negative values 

represent areas where the levee reduced depths. Depths were reduced 1 to 

1.75 ft throughout the ACM field.
MRG&P Report No. 33 99

Figure 113. High flow depth reduction due to levee alternative. 

5.1.2 Medium flow

Only the base 2018 conditions and the alternative dikes were simulated for 

the medium flow. Alternatives with the levee were not simulated due to the 

levee being above the water level. The alternative dikes performed 

similarly to how they performed during the high flow and forced more 

water to the outside of the bend. Due to the depth of flow and the dikes 

only being submerged by a few feet, the impact was greater. In Figure 114, 

there is a larger region that has a 1.5 to 2 fps increase in velocity. This can 

also be seen in the cross-sectional velocity profiles in Figures 115 to 119. 

There is also a large eddy immediately downstream of the third dike that 

can be seen forming in the middle image in Figure 114. 
MRG&P Report No. 33 100

Figure 114. Medium flow alternative velocity (2018 existing – left; alternative dikes – middle; alternative dikes minus 2018 existing – right). 
MRG&P Report No. 33 101

Figure 115. Transect 1 alternatives velocity comparison for medium flow. 

Figure 116. Transect 2 alternatives velocity comparison for medium flow. 

Figure 117. Transect 3 alternatives velocity comparison for medium flow. 
MRG&P Report No. 33 102

Figure 118. Transect 4 alternatives velocity comparison for medium flow. 

Figure 119. Transect 5 alternatives velocity comparison for medium flow. 

Water levels are shown in Figures 120 and 121 for the medium flow. 

Similar to the high flow, the stages decreased immediately downstream of 

the dikes but increased upstream. In Figure 121, there appears to be a 

more drastic change in the water surface profile, but this is due to a 

smaller range of values on the x-axis. The biggest differences are still only 

0.2 to 0.3 ft.
MRG&P Report No. 33 103

Figure 120. Alternatives water surface elevation Profile 1 comparison for medium flow. 

Figure 121. Alternatives water surface elevation Profile 2 comparison for medium flow. 
MRG&P Report No. 33 104

5.1.3 Low flow

Once again, only the existing 2018 conditions and the alternative dikes 

were simulated for the low flow. During the low flow, the dikes are 

emergent structures, and no flow is able to pass over them. Unlike the 

higher flows where the flow tends to cut more across the bar producing 

higher velocities on the inside of the bend, the low flow is more of a split 

flow around the center bar with higher velocities in the outside of the bend 

(Figure 122). Velocity profiles for the existing conditions and the 

alternative dikes are graphed in Figures 123-127. Water surface profiles for 

the low flow alternatives are presented in Figure 128 and Figure 129.
MRG&P Report No. 33 105

Figure 122. Low flow alternative velocity (2018 existing – left; alternative dikes – middle; alternative dikes minus 2018 existing – right). 
MRG&P Report No. 33 106

Figure 123. Transect 1 alternatives velocity comparison for low flow. 

Figure 124. Transect 2 alternatives velocity comparison for low flow. 

Figure 125. Transect 3 alternatives velocity comparison for low flow. 
MRG&P Report No. 33 107

Figure 126. Transect 4 alternatives velocity comparison for low flow. 

Figure 127. Transect 5 alternatives velocity comparison for low flow. 
MRG&P Report No. 33 108

Figure 128. Alternatives water surface elevation Profile 1 comparison for low flow. 

Figure 129. Alternatives water surface elevation Profile 2 comparison for low flow. 
MRG&P Report No. 33 109

6 Conclusions and Recommendations

Although heavily engineered and stabilized, the Mississippi River is still a 

highly dynamic natural system. This is evident when examining the 

variation in bathymetry along with the variation in velocities in the yearto-year comparisons. Determining the key factors impacting the changes is 

difficult in such a highly dynamic system with numerous constantly 

varying parameters. A primary focus of this study was the impact of the 

Marshall Brown Dikes. This variable was able to be isolated and 

investigated. Implementing a fixed bed model without sediment transport 

only allows the evaluation of the varying hydrodynamics impacted by the 

dike geometry. Under these circumstances, the Marshall Brown Dikes 

impact on the velocities at the bridge and upstream approach in the model 

is negligible.

There is still some uncertainty with how the river’s geomorphic response 

to the installation of the Marshall Brown Dikes impacts velocities and 

navigation. This is difficult to determine with a fixed bed model because 

the geomorphic changes must be assumed. A full sediment model with a 

mobile bed could simulate the geomorphic changes created by the dikes 

but would require significantly more time, effort, and money. While a full 

sediment model was not used, an attempt to determine how the velocities 

vary from the changing morphology over the past ten years was 

performed. The velocities did vary slightly across years, but there was no 

conclusive evidence of larger general changes to velocity patterns, related 

to the changing morphology. 

Determining the feasibility and potential impacts from constructing dikes 

and a proposed levee at Delta Point was the second major focus of this 

study. The alternative dikes were able to redistribute flow to the outside of 

the bend, significantly increasing velocities through the bridge but did not 

significantly change the velocity patterns. Increasing velocities might make 

navigating the bridge more difficult by increasing vessel speeds and 

reducing reaction times. The alternative levee had a more beneficial 

impact as it was able to reduce flood levels and velocities over the mat field 

as desired without significantly impacting velocities and stages in the 

channel for the simulated flow rate.

If concern of the Marshall Brown Dikes impact continues, conducting a 

second drogue study (similar to the 2008 data collection effort) coupled 
MRG&P Report No. 33 110

with measuring velocity profiles upstream of the bridge would provide a 

clearer view of if and how conditions have changed. Similarly, if the 

geomorphic impact of the dikes needs to be investigated, the model can be 

updated with a moveable bed and simulate sediment transport. Since the 

model has been created and validated, any future proposed alternatives 

simulations could be performed. 
MRG&P Report No. 33 111

References

Brown, Gary L. 2017. “Mass, Energy and Momentum Flux Analysis of a Bendway Weir.” 

Journal of Hydraulic Engineering 143(9).

ERDC-CHL (U.S. Army Engineer Research and Development Center, Coastal and 

Hydraulics Laboratory). 2017. Adaptive Hydraulics 2D Shallow Water (AdHSW2D) User Manual (Version 4.6). Vicksburg, MS: U.S. Army Engineer Research 

and Development Center. 

https://chl.erdc.dren.mil/adh/documentation/AdH_Manual_Hydrodynamic-Version4.6.pdf

Jones, Keaton E., David D. Abraham, and Tate O. McAlpin. 2018. Bed-Load and Water 

Surface Measurements during the 2011 Mississippi River Flood at Vicksburg, 

Mississippi. MRG&P Report No. 18. Vicksburg, MS: U.S. Army Engineer 

Research and Development Center.

USACE (US Army Corps of Engineers). 2015. 2015 Flood Control and Navigation Maps, 

Mississippi River, Cairo, Illinois to the Gulf of Mexico, Mile 953 A.H.P. to Mile 

22 B.H.P. Vicksburg, MS: US Army Corps of Engineers, Mississippi Valley 

Division. https://usace.contentdm.oclc.org/digital/collection/p16021coll10/id/10939/
MRG&P Report No. 33 112

Appendix A: Navigation Charts

Appendix A presents a Vicksburg bridges navigation chart (Figure 130) 

and a RM 443.1 to RM 428 navigation chart (Figure 131) (USACE 2015).
MRG&P Report No. 33 113

Figure 130. Vicksburg bridges navigation chart (USACE 2015). 
MRG&P Report No. 33 114

Figure 131. RM 443.1 to RM 428 navigation chart (USACE 2015). 
MRG&P Report No. 33 115

Appendix B: Top 9 ft Velocities

This appendix includes additional results showing the average velocity in 

the top 9 ft of the water column. The velocities for with and without 

Marshall Brown Dikes for the high, medium, and low flow simulations are 

plotted in Figure 132 - Figure 140. Figure 141 includes the top 9 ft

velocities for the proposed alternative dikes during the high flow.

Figure 132. High flow 2018 9 ft velocity. 
MRG&P Report No. 33 116

Figure 133. High flow 2018 dikes removed 9 ft velocity. 
MRG&P Report No. 33 117

Figure 134. High flow 9 ft velocity difference (2018 dikes removed minus 2018). 
MRG&P Report No. 33 118

Figure 135. Medium flow 2018 9 ft velocity. 
MRG&P Report No. 33 119

Figure 136. Medium flow 2018 dikes removed 9 ft velocity. 
MRG&P Report No. 33 120

Figure 137. Medium flow 9 ft velocity difference (2018 dikes removed minus 2018). 
MRG&P Report No. 33 121

Figure 138. Low flow 2018 9 ft velocity. 
MRG&P Report No. 33 122

Figure 139. Low flow 2018 dikes removed 9 ft velocity. 
MRG&P Report No. 33 123

Figure 140. Low flow 9 ft velocity difference (2018 dikes removed minus 2018). 

 
MRG&P Report No. 33 124

Figure 141. High flow alternative 9 ft velocity (2018 existing – left; alternative dikes – middle; alternative dikes minus 2018 existing – right). 
MRG&P Report No. 33 125

Unit Conversion Factors

Multiply By To Obtain 

acres 4,046.873 square meters

cubic yards 0.7645549 cubic meters

feet 0.3048 meters

miles (U.S. statute) 1,609.347 meters

square feet 0.09290304 square meters
MRG&P Report No. 33 126

Acronyms and Abbreviations

2D two-dimensional

3D three-dimensional

ACM articulated concrete mattress

ADCP Acoustic Doppler Current Profiler

AdH Adaptive Hydraulics

AdH-2DSW Adaptive Hydraulics Two-Dimensional Shallow Water Module

cfs cubic feet per second

ERDC-CHL US Army Engineer Research and Development Center, Coastal 

and Hydraulics Laboratory

fps foot/feet per second

ft foot/feet

GPS Global Positioning System 

I-20 Interstate 20

MNG Manning's n

MVK Vicksburg District

NAVD88 North American Vertical Datum of 1988

NGVD29 National Geodetic Vertical Datum of 1929

RM river mile

SDK submerged dike

URV unsubmerged rigid vegetation 

USACE US Army Corps of Engineers

USGS US Geological Survey
REPORT DOCUMENTATION PAGE Form Approved

OMB No. 0704-0188

The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data 

sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect

of this collection of information, including suggestions for reducing the burden, to Department of Defense, Washington Headquarters Services, Directorate for Information Operations

and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of

law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number.

PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS.

1. REPORT DATE 

May 2020

2. REPORT TYPE

Final Report

3. DATES COVERED (From - To)

4. TITLE AND SUBTITLE

Hydraulic Analysis and Modeling of Navigation Conditions near the Mississippi River 

Bridges in Vicksburg, Mississippi

5a. CONTRACT NUMBER

5b. GRANT NUMBER

5c. PROGRAM ELEMENT NUMBER

6. AUTHOR(S)

Keaton E. Jones, Tate O. McAlpin, and Terry N. Waller

5d. PROJECT NUMBER

107202

5e. TASK NUMBER

5f. WORK UNIT NUMBER

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)

Coastal and Hydraulics Laboratory

US Army Engineer Research and Development Center

3909 Halls Ferry Rd

Vicksburg, MS 39180-6199

8. PERFORMING

ORGANIZATION REPORT

NUMBER

MRG&P Report No. 33

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)

US Army Corps of Engineers, Vicksburg District

4155 Clay Street 

Vicksburg, MS 39183

10. SPONSOR/MONITOR'S ACRONYM(S)

MVK

11. SPONSOR/MONITOR'S

REPORT NUMBER(S)

12. DISTRIBUTION/AVAILABILITY STATEMENT

Approved for public release; distribution is unlimited.

13. SUPPLEMENTARY NOTES

14. ABSTRACT

The River and Estuarine Engineering Branch of the Coastal and Hydraulics Laboratory developed a two-dimensional numerical model of 

the Mississippi River near Vicksburg, MS, using Adaptive Hydraulics to investigate navigation conditions through the Interstate 20 and 

Old Highway 80 Bridges reach. A focus of the study was determining the Marshall Brown Dikes impact to velocities and navigation 

through the reach. Proposed dikes, focused on improving currents, were also tested to determine if they are a feasible option to improve 

navigability through the bridges. A second proposed alternative, a levee to protect the articulated concrete mattress (ACM) field, was also 

simulated to determine if flood damage to the ACM field could be successfully reduced without negatively impacting navigation. 

Velocity data from 2008 throughout the reach of concern were used for validation along with water surface elevation data from 2008, 

2011, 2016, and 2018. The Marshall Brown Dikes were shown to have a localized impact on velocities near the dikes, but the changes to 

the velocity downstream near the bridge were negligible for all tested flow rates. Simulations of the proposed dikes did not result in an 

improvement to navigation conditions, but the proposed levee was successful in decreasing velocities and depths over the ACM field.

15. SUBJECT TERMS 

Vicksburg (Miss.), Inland navigation, Mississippi River—Bridges, Numerical analysis, Vicksburg (Miss.), Waterways

16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF 

ABSTRACT

SAR

18. NUMBER 

OF 

PAGES

139

19a. NAME OF RESPONSIBLE PERSON

Keaton E. Jones a. REPORT

Unclassified

b. ABSTRACT

Unclassified

c. THIS PAGE

Unclassified 19b. TELEPHONE NUMBER (Include area code)

601-634-3558

Standard Form 298 (Rev. 8/98)

Prescribed by ANSI Std. Z39.18