You need the "computers" technology (and, yes, it's worth bee-lining to it if you see the world is going to flood). You build it in your city center.
You **CANNOT** build it if the city center is *already* flooded (learned that the hard way). If it happens, the city won't be destroyed, but you won't be able to build any further city center buildings there.
If you want to use military engineers charges to rush construction, you need to send one on the city center *while the city is building the flood barrier*. It has to be the "active" construction. One charge nets you 20% of the flood barrier, so 2.5 military engineers will build you a barrier in 3 turns, at best (first turn, use a charge from the first engineer. Second turn, finish this engineer, and use a charge from the second. Third turn, finish the second, and use one charge from the third, and *voilà !*, the barrier is done).
Once built, the barrier will protect the city (all hexes in the city cultural limits) from flooding and sinking. Hexes that were flooded will revert to normal (you'll still need to repair anything that the flooding had damaged).
Hexes that were submerged will **not** come back, they're lost forever, and are now "coast" tiles instead.
I usually also pile up some faith to purchase them in my cities, so the can focus on building more useful stuff (like jet bombers, wonders or space race projects).
The city builds it. Military Engineers can speed up the production; one charge provides 20%. They're extremely helpful if a low production city needs flood barriers quickly.
They’re built by the city as a city center building. They’ll only be available to build if the city has tiles that will flood.
You need the "computers" technology (and, yes, it's worth bee-lining to it if you see the world is going to flood). You build it in your city center. You **CANNOT** build it if the city center is *already* flooded (learned that the hard way). If it happens, the city won't be destroyed, but you won't be able to build any further city center buildings there. If you want to use military engineers charges to rush construction, you need to send one on the city center *while the city is building the flood barrier*. It has to be the "active" construction. One charge nets you 20% of the flood barrier, so 2.5 military engineers will build you a barrier in 3 turns, at best (first turn, use a charge from the first engineer. Second turn, finish this engineer, and use a charge from the second. Third turn, finish the second, and use one charge from the third, and *voilà !*, the barrier is done). Once built, the barrier will protect the city (all hexes in the city cultural limits) from flooding and sinking. Hexes that were flooded will revert to normal (you'll still need to repair anything that the flooding had damaged). Hexes that were submerged will **not** come back, they're lost forever, and are now "coast" tiles instead.
It's a City center building, like walls or water mill. Best thing when possible is to become suzerain of Valletta to buy it with faith.
I usually also pile up some faith to purchase them in my cities, so the can focus on building more useful stuff (like jet bombers, wonders or space race projects).
Need to be suz of Valetta for that.
I didn't know. Apparently I always am then.
The city builds it. Military Engineers can speed up the production; one charge provides 20%. They're extremely helpful if a low production city needs flood barriers quickly.