Rainstorm overflows are being reduced using rainwater gardens also known as "green" infrastructure, basically absorbable surfaces in sidewalk areas.
Probably the biggest solution could have been to better regulate Rainstorm runoff from private properties. But the city did not pass such legislation except for larger properties.
This is a huge gripe of mine. I live in south Queens where the majority of homes are single family detached and so many have had their yards paved to 100% coverage. It infuriates me when I see water pouring down their driveways running into the streets. I don't know why but people seem to prefer hideous barren concrete to life supporting dirt. It pains me when I see a home sold and the property is cleansed vegetation and paved. Looking around my neighborhood on 1940s.nyc is depressing.