people and deltas Flashcards
how many deltas are there worldwide?
1813
what percent of the total area of the world do deltas cover?
0.6%
what percentage of the world population do deltas hold?
4%
how has the delta’s population grown from 2000 to 2020?
237 million to 322 million
what percentage does the delta population grow each year?
1.59% each year.
how many people are there per km in 2000 and 2020?
322 people to 422
what percentage live between 3-6 m elevation?
24%
what determines the delta elevation?
the aggradation rate and how it rapidly builds up. natural conception rate, mass loading rate, eustatic SLR rate, anthropogenic compaction.
how does natural compaction affect deltas?
moving so much sediment, it pushes and bends the layers. flexes the layers. ocean crust bends due to the weight and squeezes water out of the pores.
how does mass loading effect deltas?
books on a shelf. the wet sediment id difficult to move around with. the more you load, the more pressing and adding weight. therefore, sinking elevation
how does eustatic SLR rate effect deltas?
deltas can effect local sea rise. edge of delta is a changable position.
SLR stand for?
sea level rise
how does anthropogenic compaction effect deltas?
lowers elevation A LOT. if you build on a delta, extract fossil fields, natural gas, etc- gas and fuels migrate to below sea level. this can reduce elevation 3x as fast as the mass aggradation rate.
what are the reasons for delta subsidence?
sediment supply, anthropogenic extraction, natural mass loading, relative SPR, vegetation distrubance.
what is sediment supply?
natural flooding, mostly upstream but also from the ocean. dams, levees, channels. flooding is needed to get rid of the extra sediment.
what is vegetation disturbance?
loss of marshes or mangroves, less able to trap sediment.
what are the 3 different tyeps of deltas?
natural, engineered, nature-based
what is a natural delta?
wetlands, land can rise in balance with sea level throughout accumuation.
what is engineered delta?
embanked land with human land use like agriculture, cities, harbours, industry. land rise through sedimentation is prevented by flood-protectin structures like damns or dikes.
what is nature-based deltas?
river cahnnels and open water in wetlands, with areas of human land use.
what does ACI stand for?
anthropogenic conditioning index
what does HEI stand for?
hazardous event index
what does IDI stand for?
investment deficit index
what are the risk trends for deltas worldwide?
this is mixture of ACI, HEI, and IDI.
what are the estimated future changes in exposure and vulverability for selected deltas?
IDI and ACI, indicate a change in time due to increased in exposire and increase in vulnerability based on the difference between current and future estimates.
why are human landscapes vulnerable?
where fluvial, oceanic or atmospheric processes render significant stretches of human-occupied land vulnerable to large changes and damage.
what is the result of landscape processes?
directly impact economy by causing losses, changes in construction costs. indirectly impacting market behaviour, due to feedbakc to predictions by agents insude the simulation.
what happened in 1953?
huge damage to Belgium and Netherlands, due to loss of landscape. this caused delta protection to start.
