The single most successful engineering feat which prevented Greater London and centre of global finance and trading houses from being submerge whenever the English Channel tide is unusually high is the Thames Barrier.
The mechanical wonder of 520 metres barrier spanning across the Thames, constructed between 1974-82 at the cost of then GBP 532 million at a site on the Thames estuary 10 miles east of the Westminister Palace.
It was the solution many drainage and irrigation and civil works engineers wanted to develop for the ever so often re-occuring problem. In fact, the idea came about in the 50s.
After the 1953 North Sea flood in the United Kingdom recorded 307 deaths, the idea was given more prominence and serious attention. The fact that British environmental engineers and scientists recorded that in 100 years, the water level rose by 20 cm, they anticipated that the flooding on the Thames would just be worse if a more drastic strategic solution is not put in place.
In the age where global warming is growingly problematic as the water level and earth temperature are rising, this is probably the most suitable strategic solution for a more comprehensive flood mitigation program.