An economic assessment of the amenity benefits associated with alternative coastal defence options.

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An economic assessment of the amenity benefits
associated with alternative coastal defence
options.

• Dr Mike Christie and Oliver Colman
• University of Wales Aberystwyth

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Current coastal defence
Seawall
Wooden groynes now at end of their useful life
Shingle bank
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New traditional coastal defence options for
Borth

• Replace wooden groynes
• Rock groynes
• Raise height of seawall

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An alternative coastal defence option
multi-purpose reef
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(No Transcript)
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Research aim and method

• Aim To examine local residents AMENITY values
  for alternative coastal defence options.
• Method Choice experiments

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Choice experiment attributes and levels

• Visual Appearance
• No change
• Rock Groynes
• Offshore Reef
• Seawall
• No change
• Raised wall
• Surf Conditions
• No change
• Improved
• Conditions for Family Beach Activities
• No change
• Safer conditions
• Increased taxation
• 6 levels

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Choice task Borth example
OPTION A OPTION B STATUS QUO
Visual appearance Structures made from large rocks would replace the timber groynes. Existing timber groynes with shingle bank Existing timber groynes with shingle bank
Height of seawall No change in the height of the wall Wall raised by 1 metre to reduce the likelihood of overflow No change in the height of the wall
Surf conditions Conditions for surfing would remain unchanged Conditions for surfing would improve Conditions for surfing would remain unchanged
Beach conditions for family amenity Safer conditions for beach activities Conditions for beach activities would remain unchanged Conditions for beach activities would remain unchanged
Annual tax increase You will pay an extra 15.00 tax annually over a 5 year period You will pay an extra 6.00 tax annually over a 5 year period Your tax bill will not be increased
Choice A B SQ
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Results RPL model
Non random parameters in utility function
?ASC_SQ -1.257 (-7.851)
?Visual_rock_groyne -0.441 (-6.002)
?Visual_reef 0.746 (7.381)
?Family_amenity 0.495 (4.399)
?Tax -0.015 (-4.839)
Random parameters in utility function
?Seawall 0.305 (0.987)
?Improved_surf -0.029 (-0.181)
Heterogeneity in Mean, parameter variable
?Seawall_Upper -1.005 (-1.884)
?Surf_surfer 1.116 (3.387)
LL model -796.956
LL constants only -1054.668
Pseudo-R2 24.43
Correct predictions 0.462
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Results Implicit prices
Attributes RPL
Visual_timber_groynes (all residents) -19.82 (7.23)
Visual_rock_groyne (all residents) -28.66 (8.06)
Visual_reef (all residents) 48.49 (12.84)
Seawall (all residents) 19.81 (20.12)
Seawall (Upper Borth only) -45.45 (30.49)
Improved_surf (all residents) -1.95 (10.85)
Improved surf (Surfers only) 70.59 (21.02)
Family_amenity (all residents) 32.14 (10.09)
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Key observations

• Visual timber groyne negative
• Visual rock groyne negative
• Visual reef positive
• Family amenity positive

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Key observations

• Seawall and improved surf were insignificant
• Seawall Upper Borth interaction is significant
  
• Lower Borth want generally want sea wall
• Upper Borth dont.
• Improved surf Surfer interaction is
  significant
• Surf conditions now significant for surfers, who
  want improved surf
• Non-surfers still insignificant

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Amenity value associated with coastal protection
proposals at Borth
Coastal defence option Compensating surplus value ( per household)
Replace existing groynes with timber groynes 0
Replace existing groynes with rock groynes -8.84
Replace existing groynes with a multi-purpose reef (excluding surf improvements) 98.5
Replace existing groynes with a multi-purpose reef (including surf improvements) 171.04
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Conclusions

• The multi-purpose reef option provides
  significant amenity benefits over traditional
  coastal defence options.
• Mixed views with regard to raising the seawall.
• Policy makers should consider non-market values
  in coastal defence proposals in the future.

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Thank you for your attention. Any Questions