Sandwich Coastal Resilience Program
Designing with Nature to Reduce Local Climate Vulnerability
UPDATE 2022!!!- Historic Sandwich Village Resiliency Efforts. Scroll Down or Click Here to learn more about Sandwich's continued resiliency efforts.
Welcome
The Town of Sandwich is committed to building community resilience and reducing vulnerability to the impacts of climate change. This commitment starts at the coast-- The Town's first line of defense against rising seas and extreme storms is it's coastal green infrastructure: vast beaches, rolling dunes, tall coastal banks and bluffs, and lush salt marshes. The town has invested significant resources and time to develop a detailed understanding of its evolving and dynamic coastline, and has explored unique and diverse strategies to restore, protect, and enhance these natural assets for the enjoyment and benefit of all.
In 2018, the Town of Sandwich was awarded a Planning Grant from the Massachusetts Executive Office of Energy and Environmental Affairs (EEA) to implement the Municipal Vulnerability Preparedness (MVP) Program's Community Resilience Building (CRB) framework. The MVP program was designed to help communities reduce vulnerability to climate-related hazards and build community resilience. The CRB workshop resulted in a list of implementable actions and certified the Town of Sandwich as an MVP community. As a certified MVP community, the Town of Sandwich was eligible to apply for MVP Action Grants to implement prioritized actions from the workshop.
In 2019, the Town of Sandwich received an Action Grant to develop a communications platform for the Town's coastal resilience program. This StoryMap is the hub for information related to climate change planning in the Town of Sandwich. We invite you to explore the resources below to learn about local sea level rise and storm surge projections, the Town's detailed vulnerability assessment and adaptation plan for infrastructure and natural resources, a study of the flood protection benefits provided by our barrier beach and dune system , and other ongoing coastal resilience projects.
Update 2022: Historical Sandwich Village Resiliency Efforts
In 2021, the Town of Sandwich Received an Action Grant through the MVP program to develop dynamic adaptation pathways and resilient design solutions for the Historic Sandwich Village. As part of this project, the Town is looking for public comments on the historical value and character of Sandwich Village, the existing flooding impacts of the Village, and what type of adaptation strategies would be supported by residents and other Sandwich Village stakeholders. Below are three links to online data viewers where residents and stakeholders can provide input.
Also participate by filling out this survey to describe your connection to the Historic Sandwich Village, describe your experiences with flooding, and provide input on the type of adaptation strategies that you would support. Click the turquoise button below to access the survey.
Lessons from Sandwich's Past
Over the last 20 years, Sandwich has dedicated considerable time and effort to enhance its resilience to coastal hazards. The Town's beaches are depleted of sand, resulting in high rates of erosion and increased vulnerability to coastal storms. The shorelines and barrier beaches of Sandwich create the right conditions to support large salt marsh and estuarine systems at Sandwich Harbor and Scorton Creek. The upper reaches of these systems are adjacent to developed areas of Sandwich where municipal infrastructure, businesses, and homes are located. Let's take a look at a few ways Sandwich has been adversely affected in the past. Use the arrow on the right side of the screen to scroll though several photos.
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Living in Today
Sandwich's coastline, especially the area surrounding Town Neck Beach, is susceptible to coastal change. Over the years, Sandwich has undertaken a variety of studies to better understand the local sediment dynamics and processes that are affecting the coast. The Town is actively pursuing unique strategies to create a more resilient and stable coastal beach system not just in today's climate but for the future. Below are a few examples of these ongoing initiatives.
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Town Neck Beach and Dune Nourishment
Exposed to coastal processes and the impacts of storm events, Town Neck Beach has experienced significant coastal change including the severe erosion of the beach and dune complex. Beach and dune complexes serve an important role in buffering the coast from impacts caused by Nor'easters and tropical storm events. However, Town Neck Beach has a limited sediment supply such that the barrier beach system cannot maintain a healthy beach dune complex. The degraded barrier beach system now offers minimal energy dissipation such that even small storms can result in severe storm induced flooding risks to low-lying areas in Sandwich. Thus, Sandwich has developed a rigorous nourishment plan for the beach and designed an updated dune template to enhance the existing dune. Sandwich has conducted a variety of scientific field studies including eel grass, shellfish, hard-bottom habitat and bathymetric surveys to assess potential impacts of this nourishment program.
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Scusset Beach Borrow Site
An important part in developing a Beach and Dune Nourishment program is finding a suitable source of sand material to place along the beach and enhance the dune template. A potential source of sand material for re-nourishing Town Neck Beach is Scusset Beach on the north side of the Cape Cod Canal. The north jetty interrupts the natural alongshore sediment transport and has caused significant deposition of sand material at Scusset Beach. If not for this interruption of alongshore sediment transport by the jetties, this sand material would have naturally replenished Town Neck Beach. In-situ field studies were completed to assess the suitability of this sediment material to be used in re-nourishing Town Neck Beach. Field studies included bathymetric surveys, shellfish sampling, and sediment core sampling and sediment gain size analysis.
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Dredging of Old Sandwich Harbor
Another potential source of sediment to re-nourish Town Neck Beach is Old Sandwich Harbor. Existing sand that erodes from Town Neck Beach is transported alongshore in the southeast direction and is deposited into the main creek channel of Old Sandwich Harbor. This deposition of sediment can be seen under the blue marker in the map to the right. Through daily flood and ebb tides, the Sandwich salt marsh ecosystem relies on an open connection to Cape Cod Bay through the Old Harbor creek channel. A restricted or diminished tidal range can cause degradation of water quality parameters which can lead to a change in the overall health of salt marsh ecosystems. A coastal modeling study was completed to determine if dredging sand material from within the creek channel would result in an increase in tidal range and flushing capabilities. The potential to dredge this material would not only benefit the overall health of the ecosystem but could provide suitable material for nourishing Town Neck Beach. In support of this initiative, eel grass, shellfish, and hard bottom habitat ecological surveys were conducted to better understand potential dredging impacts to the project area.
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Cape Cod Canal Section 111 Feasibility Study
Construction of the jetties at the east end of the Cape Cod Canal in 1906 has been the primary reason for the erosion issues Sandwich is experiencing. The two Canal jetties, while ensuring reduced shoaling within the Cape Cod Canal, cause an interruption of the natural longshore sediment transport from northwest to southeast. As such, the downdrift Sandwich beaches do not receive a significant amount of sediment that would normally arrive to their shoreline. In turn, a sediment starved beach, like the barrier beach at Town Neck Beach, is particularly vulnerable to erosion and breaches throughout the system. The Town of Sandwich has utilized significant resources attempting to stem the erosion impact such as the construction of groins along the beach, construction of jetties at downdrift inlets, and intermittent dune restoration projects when funding allowed. Recently the United States Army Corps of Engineers, in conjunction with the Town of Sandwich and Woods Hole Group, completed an investigation to evaluate the influence the Cape Cod Canal and its associated structures have on the adjacent shorelines and the erosional problems the coast is experiencing. Included in the report was an assessment of existing conditions, hydrodynamic wave modeling, sediment transport analysis, and the development and assessment of various alternatives. This investigation was a component of the United States Army Corps of Engineers, New England District's Cape Cod Canal Section 111 Feasibility Study.
Looking to the Future
The Commonwealth of Massachusetts has been at the forefront of climate change and resiliency planning, helping communities reduce vulnerabilities to climate-related hazards and build resilience for people, businesses, and natural systems. In 2017, Governor Baker's administration launched the Municipal Vulnerability Preparedness (MVP) program to assist communities identify and prioritize actions to enhance resilience and simultaneously disseminated local climate change projections through the resilientMA Climate Change Clearinghouse.
Sea level rise projections used for the Massachusetts Coast Flood Risk Model.
At resilientMA you will find the latest climate change projections for precipitation, temperature, and sea level rise. Additionally, the Massachusetts Coast Flood Risk Model (MC-FRM) will provide information on the combined effects of sea level rise and coastal storms. The sea level rise projections incorporated into the MC-FRM are shown in the figure to the left.
Massachusetts Coast Flood Risk Model
The Massachusetts Coastal Flood Risk Model (MC-FRM) developed by the Woods Hole Group is the most comprehensive and sophisticated model available for anticipating how climate-related hazards (sea level rise and coastal storm events) will influence future coastal flood risks in the Commonwealth (MassDOT, 2019 in publication). MC-FRM was developed for the Massachusetts Department of Transportation (MassDOT) to assess potential flooding vulnerabilities to highways and other transportation infrastructure throughout the coastline of Massachusetts. The model is based on mathematical representations of the hydrodynamic processes that affect water levels along the coast – including tides, waves, winds, storm surge, sea level rise, wave set-up, wave run-up and overtopping. These processes were modeled at a high enough resolution to identify site-specific locations in Sandwich that are vulnerable and may require adaptation responses.
The data viewer to the left allows you to explore the MC-FRM results for the Town of Sandwich in more detail. Layers included in this viewer are the Probability of Inundation and Inundation Depth for the 1% Annual Chance Event. Projections are available for Present Day, 2030 and 2070.
Use the layers button in the upper left hand corner of the data viewer to select a specific layer you want to explore.
2018 MVP Action Grant- Detailed Vulnerability Assessment
The Woods Hole Group conducted a detailed vulnerability assessment for municipal infrastructure and natural resources for the Town of Sandwich. The vulnerability assessment was funded by a Municipal Vulnerability Preparedness Program Action Grant, and focused on two top hazards identified in the Town's Community Resilience Building Workshop: sea level rise and storm surge. The study prioritized high risk assets and provided recommendations for physical adaptations and regulatory changes.
Climate Change Vulnerability/Risk Assessment and Adaptation Study
The Sandwich Climate Change Vulnerability / Risk Assessment and Adaptation Study leveraged the latest climate change projections for sea level rise and storm surge (MC-FRM), records review, and detailed infrastructure surveys to provide data on likely future flooding scenarios and identify potential flooding impacts to municipally-owned infrastructure. Adaptation strategies for high priority assets, as well as recommended changes to local by-laws and regulations, were developed jointly by Woods Hole Group and engineering partner Kleinfelder .
Taking Stock: Asset Inventory
The first step of the vulnerability assessment was to inventory all municipally owned infrastructure potentially exposed to flooding under future conditions. These assets included dams, buildings, the Boardwalk, hydrants, marina infrastructure, open space, parking lots, roadways, and septic systems.
Below is a summary of the number of assets within each category of the inventory.
What if: Evaluating the Consequence of Asset Flooding
The consequence of flooding for each of the assets was evaluated. This metric helps describe the level of impact to the community if a particular asset was compromised by flooding. For this assessment, each asset was rated on a scale of 0 - 4 (low to high consequence) for six different categories (see table to right).
Testing the waters: Determining the Probability of Flooding
Each asset has a critical elevation, defined as the elevation of flooding that would compromise the asset (ceases to function as intended). Critical elevations were developed for each asset based on records review or site surveys. Critical elevations were then compared to Water Surface Elevation (WSE) distribution curves from MC-FRM. An example WSE distribution curve for the Sandwich Fire Station is provided below. If the projected water surface elevation exceeds the critical elevation, that asset is vulnerable to flooding, and the associated probability is recorded for present day, 2030, and 2070 conditions.
Crunching the numbers: Risk Assessment
For each asset, a total risk score was then calculated by multiplying the probability of flooding by the consequence of flooding. Below is an example of an asset profile (for the Sandwich Fire Station) that displays all the data collected for this analysis.
The final risk scores for all assets can then be ranked to help communities prioritize adaptation investments over time. The figure to the right graphically displays the final risk scores for Sandwich roads. Road segments in red have the highest risk score.
Being proactive: Developing Adaptation Plans
Sandwich Fire Station #1 was identified as one of most vulnerable assets as it is critically important for emergency services and is at high-risk of flooding. Below is a rendering of potential flooding from a 1% chance event (i.e., 100-year return period event) at the Fire Station.
Rendering of Downtown Fire Station Inundation from 2030 (and 2070 dashed) 1% chance storm events.
The high risk of flooding and the importance of Fire Station #1, as well as the presence of other Town-owned assets at high risk in the vicinity prompted an exploration of potential regional adaption strategies to reduce flooding risks at the Fire Station and other parts of Sandwich Village. To the right is a figure exploring one alternative – using living shoreline techniques, an elevated railway berm, and operable flood gates to reduce flood risk to the district surrounding Mill Creek.
In its overall coastal strategy, Sandwich has committed to investing in adaptations strategies that leverage green infrastructure and nature-based solutions to reduce flooding and erosion.
The Protective Benefits of Beach and Dune Systems
Beach and dune systems like Town Neck buffer landward communities from the most severe impacts of coastal storms and can reduce flooding. Recognizing these (among other) important ecosystem services, the Town of Sandwich invests in the protection of its beaches, dunes, and coastal banks, and seeks to enhance coastal green infrastructure for future flood protection. Funded by a MVP Action Grant, Woods Hole Group completed a scenarios analysis to quantify the benefits of Sandwich's beach and dune system in protecting the local homes and businesses. The comparative modeling effort evaluated present and future flooding based on three dune conditions: existing (based on most recent elevation data), eroded (modeled assuming a 20% reduced dune elevation and a rolled-back dune location (100 ft landward), and nourished (modeled assuming the full Town Neck nourishment template (to elevation 21 ft NAVD88).
The spyglass maps below present the results of a few scenarios completed for this analysis. Use the slider bar to compare the extents of flooding from storms in today's climate and future climate conditions under different dune conditions. Use the +/- buttons to zoom in and out of the map. Click the map with the mouse to pan to the desired position.
Under Present Day conditions, a 1% annual chance (100-year) storm event produces a greater extent of coastal flooding with an eroded dune (red) than with a nourished dune (blue). Note the additional flooding across Route 6A in and around the Village.
Under 2030 conditions, a 2% annual chance (50-year) storm event produces a greater extent of coastal flooding with an eroded dune (red) than with a nourished dune (blue). Note the expanded flooding across Route 6A near the Village, and the potential for restricted access at Town Neck Road.
Under 2070 conditions, a 20% annual chance (5-year) storm event produces a greater extent of coastal flooding with an eroded dune (red) than with a nourished dune (blue). Note the potential for restricted access at Town Neck Road, and the potential for saltwater impacts at the State Fish Hatchery.
Our analysis shows that under many storm conditions, a healthy beach-dune complex is more protective against present and future flooding impacts. While the extent of flooding is helpful in determining the number of buildings potentially flooded, it doesn't capture the value of loss to these structures. Economic loss due to flooding depends on the replacement cost of the structure and its contents as well as the severity (depth) of flooding. This analysis applied depth damage curves to estimate storm damage for each dune condition and storm scenario and compared the results to understand the protective value of the Town Neck beach-dune complex on a storm-by-storm basis.
The scenario analysis demonstrated that for a projected 1% (100-year) storm event in 2030, a nourished beach-dune complex provides approximately $3 million in flood damage protection compared to an eroded dune condition. For a projected 1% (100-year) storm event in 2070, the estimated protective benefit of a nourished dune increases to approximately $5.9 million over the eroded dune scenario. Over the long term and multiple storm events, the value of Sandwich’s coastal green infrastructure becomes apparent. Protecting and enhancing beaches and dunes can provide immediate and future benefits to vulnerable residential and commercial areas, as well as enhance local ecology and beauty.
Outreach and Education
Stakeholder engagement is a critical component of any climate change resiliency strategy. Local knowledge of projected impacts from climate-related hazards and the potential for coastal resources and nature-based solutions to reduce these vulnerabilities, including an understanding of the cascading benefits of a resilient coast to low-lying inland areas, is important for project success. Here are few more ways the Town is leading the way on coastal resilience outreach and education.
Middle School STEM curriculum surrounding localized climate change
Middle School STEM Curriculum
A top priority for the Town of Sandwich was to reach out to the student demographic in Sandwich to communicate the local impacts of climate change and potential adaptation solutions. Woods Hole Group, the Department of Natural Resources, and Sandwich Public Schools teamed up to develop 7th and 8th grade STEM curriculum that adheres to the current STEM Academy standards and compliments current curriculum topics. The current 7th and 8th STEM curriculum covers climate change on a more global and national scale. This STEM curriculum makes climate change education local by enabling students to explore climate change impacts in their own Town and the importance of coastal green infrastructure to Sandwich's resilience.
Current location of Sandwich's CoastSnap.
CoastSnap Beach Monitoring
Citizen science is a powerful strategy to collect real data in real time through public participation. The Town of Sandwich is currently exploring the installation of a CoastSnap beach monitoring system to be located at Town Neck Beach. CoastSnap was designed to capture valuable information from photos taken of the beach from a fixed platform. The fixed platform creates a controlled orientation for any smart phone device to get a true measure of the changing landscape. Photos are then collected into a database, and can be analyzed to measure the changing beach width, shoreline change, and the beach response to local ocean conditions.
For More Information
The Woods Hole Group and the Sandwich Department of Natural Resources developed this platform to disseminate information about Sandwich's Coastal resilience Program.
The Municipality Vulnerability Preparedness program (MVP) was developed by the Massachusetts Executive Office of Energy and Environmental Affairs to help communities plan for climate change resiliency and provided the Town of Sandwich with funding to complete this platform. To access the latest state climate change science and data, and to learn more about Massachusetts continued efforts in climate change planning and resiliency please visit:
