[fennecfoxen]

That may be the case for de kanalen, but I don't think it explains de grachten -- that is, the Netherlands has canals criss-crossing the countryside which might accomplish flood control purposes, but when there are canals in between every other city street, that's another matter.

Either way, the article failed to explain :)

(Fun fact: the word "gracht", Dutch / Nederlands for street-canal, uses the voiced velar fricative, a sound which English eschews. Good luck pronouncing it right. :b)