Ecological Engineers

Question 1

Whats the bathtub model?

Answer 1

Instantaneous effect of sea level rise all at once.

Just follows contours and remaps it in scary ways.

Question 2

Why beware of the bathtub?

Answer 2

Marshes/ mangroves/ atoll/ landscapes all rely fundamentally on geomorphic ecologic feedbacks that determine how they respond to external environmental forcing (e.g SLR, changes in storminess, temperature).

Question 3

What is ecological engineering?

Answer 3

Interactions between plants and sediment that allow wetlands to actively engineer their position within the intertidal zone in ways that enhance their ecosystem persistence.

Question 4

How are environments vulnerable to sea level rise good at maintain/ persisting through time?

Answer 4

Exist in the first place because of feedbacks.
Given external environmental forcing conditions (SLR, storms, etc).
Then we need to consider the influence of feedbacks- geo/ eco feedbacks shape landscape morphology…but morphology also controls setting in which feedbacks operate (what size sediment is it getting etc).

Question 5

Conventional engineering

Answer 5

Ultimate solution to combat flood risks and shoreline erosion?
Dikes, levees, dams.
Deltas in wealthy countries, which now can spend £££ on conventional engineering, will see more risk long term as energy costs increase.
Time scales: yrs to decades
Accels local SLR and increase long term flood risks.

Question 6

Absent engineering (natural)

Answer 6

Channel network
Tidal inundation, river flooding
Sand and mud supplied during inundations -> trapped by wetland veg
Vertical buildings and maintenance of deltas to match SLR.

Question 7

Nature based engineering

Answer 7

Restoration of wetlands between rivers and settlements -> provide extra water storage, slow down flood propagation, reduce flood risks in pop zones.
Restored wetlands build up sediments-> regain elevation in embanked and lowered land -> survive long term SLR.
Nature based solutions typically self sustaining and cost efficient -> use natural flow to deliver sediment.

Question 8

Remember the alternative…

China’s new great wall

Answer 8

Seawalls cover 60% length of the coastline of mainland China
~11,000 km as of 2010 (Great Wall = ~ 22,000 km)
Increased >3x in two decades; land reclamation rate projected to ~ 60,000 ha/yr
Coastal region = 13% land area -> 60% GDP