Charles River Watershed Water Resources

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MNDWI calculated from January 1- October 25th, 2020 Landsat 8 OLI imagery using green and short-wave infrared bands (B3 & B5). The image shows the eastern portion of the Charles River watershed, which includes the Boston metro area. Dark blue shades indicate open water features, purple indicates built-up land cover, and yellow indicates vegetation. Flooding will be more prominent near open water features and should be considered during development and resiliency planning. Keywords: MNDWI, Landsat 8, Water, Charles River Watershed, Boston, Trista Brophy, Willow Coleman, Anna Garik, Will Peters

Assessing Flooding Vulnerability to Assist High Water Intervention and Urban Planning Programs in the Charles River Watershed

The Charles River watershed intersects 35 municipalities within the Boston Metropolitan Area and has a population of 1.2 million, making it one of the most densely populated watersheds in New England. In recent years, the watershed has observed higher rates of flood inundation, mainly due to increased development, extreme precipitation events, and increased surface runoff. As the frequency of flood events increases and a changing climate poses an ongoing threat to local communities, governments, and organizations in Massachusetts need accurate flood risk assessments. This project partnered with the Charles River Watershed Association, the Town of Natick’s Office of Sustainability, and the Massachusetts Audubon Society to assess the potential for watershed degradation, flood vulnerability, and flood susceptibility in the watershed. The team used Landsat 5 Thematic Mapper (TM), Landsat 8 Operational Land Imager (OLI), Sentinel-1 C-Band Synthetic Aperture Radar (C-SAR), and Sentinel-2 MultiSpectral Instrument (MSI) to assess the feasibility of identifying flood events using remote sensing. After identifying images that overlapped with the reported flood events, the team concluded that it was not feasible to use Earth observation data to detect localized flooding. Instead, the Federal Emergency Management Agency (FEMA) 100-year floodplain was used as a proxy for areas where flooding may occur. The team used statistical analysis and supervised classification to develop a flood susceptibility map, incorporating factors like soil drainage, height above nearest drainage, and topographic wetness index. This was overlaid with demographic and socioeconomic data to create a flood vulnerability map. The flood susceptibility map captured over 2/3 of reported flood events in the watershed, an improvement over the 1/3 of events captured by the FEMA 100-year and 500-year floodplain maps.

Location
Massachusetts - Boston
Term
Fall 2020
Partner(s)
Town of Natick, Office of Sustainability
Massachusetts Audubon Society
Charles River Watershed Association
NASA Earth Observations
Landsat 5 TM Surface reflectance
Landsat 8 OLI
Sentinel-1 C-SAR
Sentinel-2 MSI
Team
Trista Brophy (Project Lead)
Willow Coleman
Anna Garik
Will Peters
Advisor(s)
Dr. Cedric Fichot (Boston University)
Dr. Kenton Ross (NASA Langley Research Center)