Presentation given by: Eric Grossman, USGS

1. Nisqually Delta Sediment Budget & Transport Dynamics
to Inform Restoration and Climate Change Planning
Eric Grossman, U.S. Geological Survey
Guy Gelfenbaum,
Andrew Stevens,
Chris Curran,
Steve Rubin,
Mike Hayes
PCMSC, WAWSC Nisqually Indian Tribe
WERC, WFRC

2. How do physical processes redistribute sediment and organics
to shape marshes, channels, nearshore/tidal flats?

3. Tides/Hydrodynamics
Fish, Substrate,
Invertebrates (food-prey)
Elevation, Vegetation,
Water Quality

4. Conceptual Model and Methods
Methods:
1. GIS-Based “RAP” Model
2. Hydrodynamic Model
lost
3. Field Measurements
Sediment
Delivery

5. 1. “Rapid Assessment Protocol” - Potential Sediment Accretion
Distribute sediment load scaled by transport connectivity
Data Needs:
1. Sediment load
2. Topography (DEM)
3. Tidal Data lost
Sediment
20-100K TY Czuba et al. 2011
4.5-23.0K m3/yr 20-100k TY
USGS, 1974; This study

6. 1. “Rapid Assessment Protocol” - Potential Sediment Accretion
Distribute sediment load scaled by transport connectivity
Data Needs:
1. Sediment load
2. Topography (DEM) lost
3. Tidal Data
11-28%
Grossman and Horne (in prep)
20-100K TY
4.5-23.0K m3/yr

7. 1. “Rapid Assessment Protocol” - Potential Sediment Accretion
Distribute sediment load scaled by transport connectivity
lost
11-28%
20-100K TY Grossman and Horne (in prep)
4.5-23.0K m3/yr

8. 2. Process-based hydrodynamic & sediment transport model
Delft3D couples:
wave - current
interaction
FLOW WAVES
2 or
Bathymetry
3D
TRANSP BOTTOM
Sediment transport (van Rijn, 1993)
Dynamic Morphology
Wetting drying
Vegetation – momentum
(Baptist, 2005; Uittenboogaard, 2003)
~20-30 m grid resolution in
the restoration area

9. 2. Delft3D hydrodynamic & sediment transport model
Tidal forcing well characterized
Tidal inundation reasonably modeled;
some channels not resolved properly
Tidal channel currents well
modeled for portions of the
tidal cycle. Roughness
(vegetation) not properly
characterized, yet!

10. Role of vegetation on
hydrodynamics & sediment
information need

11. Modeled Connectivity
1-Month time period,
Avg river discharge:
70 m3/s

12. 3. Field Measurements - Methods
Fluvial Inputs
River Discharge, Sediment Load
(2-yrs; 15-min)
Nearshore Hydrodynamics
Tides, Currents, Turbidity
(2-yr, 3-mo; 5-min)
WL 1 3
Currents, SSC, X-Sections
(Synoptic: tides, Qw)
WL
WL
WL
WL

13. 3. Field Results: Fluvial inputs, WY2011

14. 3. Field Results: Fluvial inputs, WY2011
Fines (silts and clays)
~48% of total load

15. 3. Field Results: River-Marsh Connectivity
Marsh Turbidity
mean = 0.19
River Turbidity
River Turbidity
Marsh Turbidity

16. 3. Field Results: Channel Velocities, Discharge

17. 3. Field Results: Channel Discharge
McAllister
-10.1 cms
Small Net Flow in
(1.6 cms, <6% river) Area1
2.1 cms
2.1 1.1 3.1 2.2
Madrone
10.1
1.1 cms
Leschi
3.1 cms
Area3
2.2 cms

18. 3. Field Measurements: Nearshore Sediments & Flux
Suspended sediment
tracks ~1:1 with
turbidity
Nearshore turbidity
20-50% of river

19. 3. Field Results: Channel Sediment Flux
Net Flux into Marshes
(370 m3/yr)
Potential Accretion
~0.12mm/yr
2.1 1.1 3.1 2.2
10.1
0.12 mm/yr

20. Vulnerability? Cumulative Impacts? Adaptive Management?
44M m3 of sediment since 1945
(14-70x annual load)

21. Nearshore Response: Extensive channel incision
Feb 2009 Aug 2011
25 m
2m
1-2 m of incision
10-40 m widening
2009 ~5 km of channels
Sediment
2011 redistributed
367,500 m3

22. Nearshore Response: Sand export
Photo=Jul 2011
Mapping
Aug 2012
50m

23. Nearshore Response: Sand export
McAllister Creek
Jul 2009 Jul 2010
Leading edge
Sand bar
incision
Leading edge

26. “Functional” Channel Habitat – Salinity Gradients

27. “Functional” Channel Habitat – Salinity
high tide
2 hrs into ebb
River
Salt Wedge

28. Climate Change and Sea Level Rise
Winds/Waves
Observations
following maximum
model prediction
Lower rate due
to wind stress?
Rate ~3.75 mm/yr (2x the 20th century
Will sea level rise
Marshes and coastal habitats response?
accelerate if it
Brominski et al. 2011 relaxes?
IPCC. 2007; Church and White, 2011

29. “Green” Infrastructure: Coastal habitats to buffer impacts
Example, Stillaguamish Delta
1964
Low
Marsh
Low
Marsh
Boundary
Boundary
1964
2004
2012
Restoration

30. GCM-RCM Dynamic Downscaling: Hydrology, Sediment
Variable Infiltration Capacity (6km)
ECHAM5* & CCSM3 (A1B, A2)
WRF
DHSVM (100m2)

31. Projected Climate Impacts to Sediment Delivery
Increase and earlier Seasonal sediment transport model
seasonal runoff
4
2080s
Sediment Load (MT/month)
Curran and Grossman (In Review)
3
Increase
in
flood
and
sediment
2
1
2010
0
Hamlet and Grossman (in prep)

32. Adaptive Management
Opportunity?
Simulated levee breach

33. Model Results – Mud Deposition

34. http://coastalresilience.org

36. Flow to marsh = 3-6% of the river
Suspended sediment concentrations = 20-50% river
Sand exporting from marshes
Potential Accretion Rate:
<2 mm/yr (RAP); <0.3 mm/yr (measurements)
2010-2011 river flow was low
Adaptive Management:
1-Alder Lake traps >15x equiv. annual sediment load to delta
2-New Distributary?
Climate Change Adaptation and Resilience
1-Changes in Sediment delivery and fate
2-Sea level rise/waves (erosion, channel salinities)
3-Ecosystem functional response?
Information Needs
1-Interaction of vegetation-hydrodynamics-geomorphology
2-Test fish use of “functional” channels (salinity gradients)

37. egrossman@usgs.gov
Western Washington University
Any interested students please contact Eric
Coastalresilience.org
Salishsearestoration.org

39. Simulated
Flood
Event
Modeling
Approach – Fine
Sediment
Dispersal
Investigate three scenarios
1. Flow Only (tides and
river flood)
2. Flow and Waves
(tides, river flood,
and waves)
3. Flow + River Breach
(tides, river flood,
and river breach)