FLOOD STRATEGIES

Cambridge can manage and mitigate the impacts of climate change-driven flood risk by pursuing actions that will reduce or mitigate threats. But this will require regional coordination.

For example, for sea level rise flooding, we may need to construct barriers at key points along the coast to block storm surges. For precipitation-driven flooding, the City will need to increase flood storage by using more detention basins, infiltration systems, and storage tanks.

But it is unlikely Cambridge can eliminate all flood risk.This means that some measures will need to be taken to make people, buildings, and infrastructure more resilient to flooding. The City is committed to implement measures for the 10% flooding risk of 2070 to be no worse than the 10% risk of today.

Managing flood risk requires a collective effort on the part of the City, residents, institutions, and businesses, as well as other cities in the region and the state. Residential, commercial, and institutional property owners will need to do their part to protect their properties. The City will need to do its part by investing in infrastructure and critical facilities and by working with the state and region on regional solutions. New development will need to design and build projects that are resilient to flooding.

A key indicator of a prepared, connected community is the density and diversity of community resources available for constructing networks and providing critical support in times of crisis.

Cambridge already has a rich network of community organizations, an asset we should build upon to successfully enhance how people and resources are connected. The City is working with community organizations to further develop a strong support network. 

The community can take practical steps to be prepared for flooding by getting to know neighbors, learning who may need help in an emergency, and joining the many local climate change organizations in Cambridge.

It is encouraged for new buildings to be designed for flood risks projected for 2070 instead of to the flood levels of the past. The target is for all new buildings in Cambridge to be built to sustain functionality and protect to the 2070 10% flood elevation, and to recover from the 2070 1% flood elevation.

The City has developed the Flood Viewer, an informational tool for the Cambridge community to assess the flood elevation for your property.

To view your property, click the map to interact. Zoom in with the +/- buttons in the top left corner. Once zoomed in, left click once to identify the property with the risk information. For the full web mapping experience, click the launch button listed in the top right corner.

The City is committed to stormwater infrastructure improvements so that flooding from a 10-year, 24-hour precipitation event by 2070 is no worse than flooding from a 10-year, 24-hour storm of today. This commitment will require upgrading the City’s infrastructure accordingly to capture a significant volume of stormwater during intense rain events and reduce runoff.

These infrastructure investments are already underway and include the 500,000-gallon underground stormwater storage tank installed under the City Parking Lot 6 in Central Square and the planned 1.2 million-gallon stormwater tank that will be part of the Tobin School reconstruction project. Smaller measures, like installing porous pavement and leaching catch basins, also contribute toward reducing runoff during intense rain events.

Implementing green and gray infrastructure strategies together for flood mitigation provides an opportunity to achieve multiple co-benefits, one of which is to effectively mitigate flooding from a high-intensity, short-duration storm (cloud burst, thunderstorm, or flash flood).  

Gray infrastructure implementation, such as pipe upsizing, flow rerouting, and storage tank installation, is usually effective to reduce flood volume in areas where flow converges. 

Green infrastructure implementation in an urban setting, such as a green roof and a rain garden, usually needs to be widespread and can be effective in reducing flooding in downstream subcatchments. Green infrastructure also lowers urban temperature and mitigates the urban heat island impact.

A flood-resilient Cambridge means protecting our buildings, infrastructure, and communities so we are better prepared to mitigate future flood risks and able to enhance the quality of our natural environment. No single project can address increasing flood risk. Rather, the following must be achieved:

• A combination of large and small infrastructure projects completed on private and public property, in the City and throughout the region, that make Cambridge flood resilient.

• Private property owners taking action with their own properties to make Cambridge flood resilient.
• All residents must be accounted for, including residents who are more vulnerable, have low incomes, and are renters.

This document describes a range of resiliency strategies in an easy-to-read format. The document is based on technical reports that can be found at the below link.

 Click to view the Resilient Cambridge Plan 

The Resilient Cambridge Handbook is a companion document to the City’s Resilient Cambridge document. The Handbook is a practical guide for different stakeholders within Cambridge.

 Click to view the Resilient Cambridge Handbook 

The City developed a set of four toolkits to help prepare for extreme heat and flooding. Funded by the state’s Municipal Vulnerability Preparedness grant program (MVP), these toolkits address the unique resiliency needs of renters, homeowners, small businesses, and large organizations.

Nature, like people, benefits when it is part of a network or system. Resilient Cambridge aims to look at the landscape as an integrated system with recommendations that foster a holistically greener, dryer City. 

Planning for this "new normal" requires imaginative and responsive changes by the City and the community. Resilient Cambridge is substantive and optimistic and provides a comprehensive set of actions and strategies.

To find out about the plan for a flood-resilient Cambridge, see the Resilient Cambridge Handbook.