After recently writing about Where Can Pregnant Women Go? I decided to dust off an old project of mine: "what will Great Britain look like when the seas rise?" The algorithm to solve the two questions is the same: "where is accessible (from the sea) up to X metres ASL without having to go over X metres ASL to get there?" - whether the thing that is doing the accessing is a pregnant women or an ocean the algorithm is the same. I therefore started from WCPWG (Where Can Pregnant Women Go?) and created RSL (Rising Sea Levels) to answer this question.
For this project I used the excellent OS Terrain 50 dataset to provide the elevation data as 50m by 50m pixels. An animation of the first 500m is shown below.
Now obviously a 500m increase in the sea level is quite extreme. As a more realistic specific study I have included the frames for 0m, 1m, 2m, 3m and 4m below.
Cambridgeshire and north-west Lincolnshire take the brunt of the flooding. It is worth also remembering here that some parts of Great Britain are below sea level already. For instance, Holme Fen (in Cambridgeshire) is believed to be the lowest point in Great Britain at -2.75m ASL. This leads to two further observations:
- the initial map for a sea level rise of 0m ASL is slightly wrong because the dykes holding the sea out from some of these low-lying areas do not show up in the 50m by 50m grid provided in the dataset
- for the low-lying areas that are correctly kept dry (because their dykes are large enough to show up on the 50m by 50m gridded dataset) then it really doesn't take much of a sea level rise for them to flood
Personally, I am quite surprised by how far the flooding in Cambridgeshire extends - it has probably gone inland by 30 miles or more. If you are interested you may want to read about The Fens.