River Delta Restoration and Hydrodynamics

Topic

Topic pages summarize knowledge and resources within a subject area

• Anthropogenic Topics
  • Climate Change
  • Infrastructure
    • Aquaculture
    • Energy
    • Flood Management
    • Shoreline Management
    • Transportation
    • Water Management
  • Land Use
    • Agriculture
    • Conservation Lands
    • Forestry
    • Industrial
    • Rural
    • Urban
  • Socioeconomics
• Ecosystem Topics
  • Biology
  • Ecology
  • Geophysics
  • Landform

Salish Sea References

• Watershed Characterization Mapper
• The Encyclopedia of Puget Sound
• PRISM Project Search
• Washington Coastal Atlas
• WDFW's Salmonscape Map

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Natural River Deltas have a structure defined by the interacting processes of tides and rivers, mediated by Vegetation , Large Woody Debris creating gradients of Salinity, inundation, and patterns of channel formation and switching. In degraded river these processes are altered, and restoration aims to restore these processes to support the natural formation and maintenance of habitat critical for species like Salmon, Birds, and Beaver. A body of observation Research and Monitoring currently informs River Delta Restoration

Water Quality

• Effects of Exposed Tidal Flats on Water Temperature in the Snohomish Estuary
• Snohomish Estuary Restoration Effects on Temperature, Salinity, and Tides

Sediment Transport

• Czuba et al 2011 sediment budgets in puget sound rivers describes the variable levels of sediment discharge in different rivers.
• Cereghino 2020 rivers of water and mud shows though an infographic
• Nisqually River Delta has constrained overbank flow, which routs sediment transport away from the Nisqually Refuge Restoration
• Skagit Delta has experienced distributary flipping in the North Fork, resulting in change

Large Woody Debris

• Designing large wood placement in tidal marshes

Distributary Switching

Distributary connections are necessary to spread sediment laden river water to sustain marsh function and delta resilience in the face of sea level rise. Distributary systems are commonly simplified or constrained by agricultural and industrial development.

• Distributary configuration affects the routing of sediment, large woody debris and freshwater, and the connectivity of estuarine habitats for fish.
• While some projects may result in distributary reconnection (Stillaguamish Old Channel, Red Salmon Slough Restoration, Port Susan Restoration) and distributary reconstruction projects have been discussed for the Skagit Delta and Snohomish Delta and Nisqually Delta, we have limited ability to predict the effects of distributary configuration on sediment deposition.
• Fir Island Farm Restoration is an example of a project that is more removed from distributary nourishment than other projects in the Skagit Delta
• Some initial work associated with the Nisqually Refuge Restoration suggests that low sediment delivery by the river, combined with a weak connection between the river and restoration site is resulting in limited delta accretion.
• Aerial photo observations associated with the Port Susan Restoration show loss of marsh area in areas with limited distributary connections, and expansion of marsh area in areas receiving river flood waters. Ongoing monitoring is describing patterns of sediment deposition across the face of Florence Island.
• The landscape location and the design of levee and dike removal projects may affect wave energy, freshwater and suspended sediment routing, and patterns of salinity intrusion. These may substantially affect the function of existing wetlands. Thus some projects may substantially improve ecosystem resilience to climate impacts by increasing retention of river sediment in wetlands. On the other hand some actions may create unstable systems, or degrade existing marsh as a new hydrodynamic and sediment regime may result in marsh erosion.
• Existing projects are commonly located opportunistically, based on landowner willingness, and hydrodynamic design may be poorly informed or constrained by infrastructure or stakeholder interests (like trails development requiring retention of levees).
• We need exemplary projects that predict and verify the effects of site position and design on off-site marsh formation processes in a way that builds a more generalized project development policy.
• A river may only support a limited number of distributary channels. The phenomena of distributary switching has been explored in the Skagit (Need citation).
• File:Grossman 2013 delta sediment dynamics presentation.pptx summarizes observations of distributary distribution on delta sediment deposition among multiple systems.
• Czuba et al 2011 provides a summary of our current limited knowledge of sediment budgets on major rivers.
• USGS has been working to increase instrumentation that will allow estimates of annual sediment budget.
• Episodic events may radically change river sediment output, such as the effects of the Oso landslide on the Stillaguamish Delta.

Efforts and Products in Hydrodynamics, River Delta, and Restoration

  Efforts

• Automating Landscape Connectivity for Puget Sound River Deltas and Pocket Estuaries
• Effects of Exposed Tidal Flats on Water Temperature in the Snohomish Estuary
• Snohomish Delta Ecosystem Monitoring and Evaluation
• Snohomish Estuary Restoration Effects on Temperature, Salinity, and Tides

  Products

2 documents in Hydrodynamics,River Delta and Restoration

• Hood 2014 natural tidal channel model
• Yang et al. 2010 hydrodynamic and ecological assessment of nearshore restoration

facts or skills acquired by a person through experience or education.

particles of clay, silt, sand, gravel, or cobble, transported by water, are called sediment.