Extreme Rainfall Adaptation - NYC Mayor's Office of Climate and Environmental Justice
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Extreme Rainfall Adaptation

NYC is using a multi-layered strategy to prepare for extreme rainfall. Flooding from extreme rain can happen in coastal and inland areas, with low-lying and highly impervious areas at greater risk.

Climate change is bringing more intense storms to NYC. NYC will be resilient to these storms through an approach that combines traditional grey infrastructure and innovative green infrastructure. Reducing risk from extreme rainfall requires a multi-layered strategy with investments in infrastructure adaptation, building level protection, data collection, and community engagement. 

 NYC is using the latest climate science better understand stormwater flood vulnerability and use the most effective strategies to reduce risk.

  • NYC is conducting new climate analyses that characterize current and future extreme heavy rainfall in NYC.
  • Measuring real-time flood data through the FloodNet sensor network.
  • Studying the strategic deployment of backwater valves and the potential to install these devices in the most at-risk residential buildings, through a FEMA Flood Mitigation Assistance grant, to protect homes, businesses, and public health from wastewater backing up from the sewer during extreme storms.
  • Published NYC Stormwater Flood Maps, showing where stormwater flooding is most likely under current and future conditions.

Over the last three decades, NYC has transformed its approach to stormwater management and resilience to extreme rainfall. 

  • Implementing immediate action for communities and vulnerable populations through Rainfall Ready NYC – an action plan that outlines short-term steps New Yorkers and city government can take to prepare for extreme rain together.
  • Building out sewers with 125 miles of new/updated sewer infrastructure in the last 5 years. In Southeast Queens alone, DEP has completed 18 of 44 projects with another 17 in various stages of design, procurement, and construction.
  • Optimizing sewer performance through new and upgraded infrastructure, enhanced maintenance, and employing new technologies to identify emerging issues and target solutions for this critical infrastructure.
  • Maximizing stormwater capture on public and private buildings and infrastructure through the 2022 Unified Stormwater Rule, which will require developers of large parcels to retain as much stormwater on site as possible and detain the rest onsite.
  • Constructed over 11,000 green infrastructure assets and 17,000 linear feet of porous pavement to capture heavy rainfall, improve water quality, and prevent flooding, using nature-based measures. Expand this program, including curbside rain gardens and stormwater medians.
  • Completed 84 Bluebelt projects across three boroughs and piloted stream daylighting to capture and manage stormwater using large-scale nature-based measures.
  • Expanding cloudburst management (projects that use green and grey approaches to manage large volumes of stormwater) with a focus on vulnerable populations with at least 4 new locations to be announced in 2022 and more to come. Additionally, advancing the cloudburst project at NYCHA’s Clinton Houses campus in East Harlem (Learn more about Cloudburst Management).
  • Expanded outreach via FloodHelpNY.org on flood risk and flood insurance beyond Sandy-impacted areas to increase awareness and flood insurance uptake among both homeowners and renters in communities across NYC.

Adapting to extreme rainfall requires implementation of a wide range of large-scale and city-wide stormwater projects. 

  • Completing sewer buildout in underserved areas.
  • Evaluating drainage standards given the realities of climate change and considering projected sea level rise and rainfall intensity as well as environmental justice when planning for future drainage infrastructure.
  • Expanding the green infrastructure program, which mimics natural systems to improve water quality and reduce stormwater volume, to all parts of the City, including an expansion of the successful porous pavement pilot.
  • Creating a Bluebelt plan to prioritize evaluation and investment in these large-scale natural systems.
  • Incorporating cloudburst design principles where feasible into all city construction, starting with the most vulnerable areas.
  • Growing Resilient NYC Partners, an NYC-funded program to support private property owners to build rain gardens, fix drainage issues, replace paved areas, and other stormwater resiliency efforts.
  • Growing a green workforce through a robust green infrastructure maintenance program.
  • Expand FloodNet to 500 sensors over the next 5 years, with locations to be determined by an analysis of stormwater risk, tidal flooding risk, storm damages, environmental justice history, social vulnerability, critical infrastructure, and proximity to wireless network connections.
  • Supporting small businesses, the backbone of the City’s economy, through expanding SBS Business PREP (BPREP) citywide to help small businesses better prepare for emergencies like those caused by flooding and power outages. The City is expanding the program through a $3M commitment to reach an additional 1,040 businesses citywide, on top of the $7.1 million already invested.
  • Working with city agency, non-profit, and private partners to develop programs, resources, and financing to support critical infrastructure protections; and to deploy building-level retrofits that are not only resilient but sustainable in single and multi-family buildings, such as backwater valves, installation of flood-resistant materials, and the elevation of mechanical systems, in at-risk communities.

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When we bring our voices, our action, and our advocacy to our schools, our homes, and our workplaces, we can create a more sustainable and resilient future for the 8.3 million people who call our five boroughs home.

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