what you ask for really isnt very easy to answer , heres a paper on predicting where flooding would occur based upon many factors
I wouldnt get into the paper except for general information.
For your information I would call either the streets department or sewer and water department (NYC has its own EPA with engineers and GIS folks).
Id ask one of the engineers for mapping information that includes your building. They have all kinds of facilities maps in the GIS system and maybe they will let you look em over if it isnt part of a "Homeland Security" issue. (Lots of cities now have much stricter rules governing data access )
USGS produces topo maps that cover the city and these re updated evry 25 years or more frequently as projects warrant.
The ability to take that data and compute flood insurance information is a whole nother step. You can also get a copy of the FLOOD INSURANCE STUDY for NYC/NY . Thats done by FEMA usually under some contrqct to n gency or some engineering company. Id seen the flood insurance report for NYC a yer or so back so Im sure its on the net (google is our friend)
Most of these reports are blah blah bl;ah so have lots of coffee if you want to delve into finding the specific flood transect that includes your building (Knowing the map transect you live on is a big head start).
I think Georgeob's engineering company actually does these studies so he may have some way better data.