In researching requirements for ADU (Accessory dwelling units) under review by NYC, I found out that NYC requires that "For basement conversions, the applicable ADU space must meet ceiling height requirements prior to conversion and must be located outside of the 2050 Stormwater Flood area as well as the 2100’s 100-year coastal flood zone." Here are the NYC Storwater Flood Maps
New York City is facing multiple climate hazards that will impact daily life in the future. Coastal storms, heat waves, sea level rise impacts, and extreme rain will strain our infrastructure and put New York City’s homes and businesses at risk. As climate change continues, these impacts are predicted to worsen in the coming decades.
To help New Yorkers understand and prepare for this risk, the City has created three rainfall-based flooding maps. The maps show moderate stormwater flooding scenarios under current and future sea level rise conditions, as well as an extreme stormwater flooding scenario under future conditions. These maps are the first step to better understand the impacts of increasing rainfall in NYC.
Protecting New Yorkers from the damaging effects of stormwater flooding in the immediate term requires action from both City government and New Yorkers. In July 2022, the City released Rainfall Ready NYC at http://rainfallready.nyc/, which outlines the responsibilities New Yorkers and City government must share to combat intense storms, together, today. If your property is adjacent to or within the flood area indicated on the New York City Stormwater Flood maps, please visit Rainfall Ready today to learn what you can do to prepare for the next flood.
To learn more about the City’s long-term plan to prepare for increased rainfall, read the NYC Stormwater Resiliency Plan at nyc.gov/resiliency.
How to Understand these Maps
The three maps show a range of flood scenarios to help New Yorkers understand how stormwater flood patterns may change over time. They assume that rain occurs uniformly across the city, that the drainage network is functioning as designed (for example, that catch basins do not have leaves matting over the tops), and that large properties, such as airports, have their own on-site drainage systems. They do NOT account for the potential benefits of coastal protection projects currently under design or construction.
To see maps click here: https://experience.arcgis.com/experience/26f9c4b85a8b47168eba42e771be2dc9/?draft=true