Deltaic processes are governed by numerous factors including the characteristics of inflowing sediment, receiving basin (e.g. water depth, tidal range, circulation pattern, and wind field), and substrate (e.g. sediment type, erodibility, etc.). This topic is of importance to major deltas, especially those experiencing land loss due to subsidence and sea level rise. The Mississippi River Delta is an example where a number of sediment diversions are considered to minimize and reverse the severe loss of wetlands. Historically, the Mississippi River played a significant role in providing sediment, nutrients, and fresh water to support Louisiana’s coastal wetland system. As such, a systems perspective for regional-scale implementation of diversions is important. Recent field observations, coupled with numerical modeling, provided insights toward a system-scale approach to design, evaluate and operate sediment diversions. These recent research activities investigate the uncertainties associated with morphodynamic processes both on the river and receiving basin sides; and identify the critical parameters influencing the overall magnitude and rate of building new land and sustaining existing wetland areas. Specifically, this research discusses the impact of extracting significant amount of sediment and water from fluvial rivers; the ability to efficiently convey sediment to the receiving basins, and the ability to retain such material to build new land and sustain existing wetland.

1. OPTIMIZING SEDIMENT CAPTURE
AND DELIVERY
Ehab Meselhe, PhD, PE
Director of Natural Systems Modeling
INTEGRATING APPLIED RESEARCH.
LINKING KNOWLEDGE TO ACTION.
BUILDING PARTNERSHIPS.

2. P R E S E N TAT I O N O V E R V I EW
Analysis/Validation of large scale dynamics
Application of large scale models
Analysis/validation of local riverine dynamics
Applications of local riverine dynamics
Analysis/validation of receiving area land building
Application of receiving area land building

3. G EOMO R P H I C A S S E S SME N T
Document the historic trends of the channel system
Establish the current stability of the channel system and
identify the dominant processes and features within
the system
Acknowledgement: Little & Biedenharn
3

4. 1 9 6 0 S TO 1 9 7 0 S
4

5. 1 9 7 0 S TO 1 9 9 0 S
5

6. 1 9 9 0 S TO 2 0 0 0 S
6

7. BUILDING STRONG®
Validation of large scale dynamics (Heath and Thomas)
7

8. A P P L I C AT I O N O F L A R G E S C A L E
MO D E L S : LONG TERM IMPACT OF
MULTIPLE DIVERSIONS ON RIVER

9. BUILDING STRONG®
Future With Project (PR#2)
(Heath and Thomas)
Map from 2012 Coastal Master Plan
5,000 CFS
35,000 CFS
75,000 CFS
50,000 CFS
50,000 CFS

10. BUILDING STRONG®
(Heath and Thomas)

11. A N A LY S I S / VA L I D AT I O N O F LO C A L
R I V E R I N E D Y N AMI C S : LOCAL RIVER
RESPONSE TO LARGE DIVERSION

12. BUILDING STRONG®
Bathymetric change (FLOOD 2011) (Sadid and Meselhe)

13. BUILDING STRONG®
Bathymetric change (June 2011-June 2012)

14. BUILDING STRONG®
Volume of Erosion and Accretion

15. BUILDING STRONG®
2011 Flood Event-Sand Budget
29%
17%
8%
2%

16. A P P L I C AT I O N S O F LO C A L R I V E R I N E
D Y N AMI C S

17. BUILDING STRONG®
Impact of Diversion Design on Capture Efficiency (Gaweesh and Meselhe)
17

18. BUILDING STRONG®
18
Invert Elevation
Alignment Angle
Size
Impact of Diversion Design on Capture Efficiency

19. A N A LY S I S / VA L I D AT I O N O F
R E C E I V I N G A R E A L A N D B U I L D I N G

20. WE S T B AY D I V E R S I O N
Acknowledgement: Meselhe, Allison, Khadka & Deltares
To West Bay
(Receiving Basin)

21. 2 0 0 9 - 2 0 1 1 V O L UME S

22. 2 0 0 9 - 2 0 1 1 L A N D B U I L D I N G
( ~ 3 K M 2 / 7 5 0 A C R E S )

23. A P P L I C AT I O N O F R E C E I V I N G A R E A
L A N D B U I L D I N G

24. MID-BARATARIA LAND BUILDING
ANALYSIS (WATER INSTITUTE AND HDR)
Alternatives:
75,000 CFS
50,000 CFS
35,000 CFS
25,000 CFS

27. C L O S I N G R EMA R K S
The synergy between Diversions and Dredging offers:
• Diversions: Sustainable solution
• Diversions: Significant new land building and
preserve existing wetlands [fine material]
• Dredging/Placement: Near term land building
• Dredging/Placement: Reduced erosion
• Dredging/Placement: Enhanced sediment retention
• Combined: May reduce shoaling near the HOP
Impacts on Fisheries and Nutrients are being analyzed

28. THANK YOU
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