Amsterdam has this problem as well, it is now generally discouraged to pave your garden. Moreover projects using the "rain away tile" are popping up: http://rainaway.nl/
And also a the term "tegel-tax" (tile-tax) is introduced. The idea is to tax real estate based on the amount of non-permeable surface it has. More non-permeable surface resulting in a higher tax bill. Satellite & plane imaging combined with computational analysis would enable enforcement.