Coastal Erosion and Management Chapter 20

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Coastal Erosion and ManagementChapter 20
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Erosion due to El Nino along Pacific Coast
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70 of Worlds Coasts Eroding

• Sea level rise and sediment supply.
• Human induced.

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Human Induced Erosion

• Decreased sediment supply in rivers
• Texas/Brazos River 70 decrease in load due to
  dams (2 x 106 m3)
• Japan Overpumping from aquifers.
• Louisiana Dams and subsidence

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Human Induced Erosion

• Sand mining
• Canada Beach sediment for aggregate.
• Ireland Agriculture.
• South Africa Mining diamonds.

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Alternatives?

• SHORE NORMAL
• Seawalls
• Concentration of energy on beach
• Increase backwash
• Increase beach H2O tables erosion
• Increase pore pressure beach slumping
• Seawalls Beach Nourishment
• Higher rates of erosion during hurricanes than
  neighboring, natural areas. WHY?
• Tetrapods reduce beach lowering
• Riprap reduce beach lowering
• Beach Nourishment

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Alongshore
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Breakwaters
Detached Breakwaters
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Jetties
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Groins During Calm and Storm Conditions
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Soft Option

• Beach Nourishment
• Cost?
• Source of sand/sediment
• Effect/s of sand removal
• Longevity of new beach (1-7 yrs.)
• Technology
• Pre-nourishment feasibility studies
• Funding sources
• Federal
• State
• Local

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Durability of Nourished Beaches