A Framework for Considering Climate Change in Transportation and Land Use Scenario Planning
Appendix E: Vulnerable Area Map and Key
Interagency Transportation, Land Use, and Climate Change Pilot Project
Expert Elicitation on Climate Change Impacts on Cape Cod - July 21, 2010
Index of Vulnerable Areas and Notes
- Vulnerable coastal zone. Notes: Hatches Harbor dike is currently open, but its ability to mitigate the impacts of sea level rise is limited. Risk: The area could be safe for 20 years or so but is likely vulnerable in any major storm.
- Vulnerable due to erosion.
- All of Provincetown's roads, especially Commercial Street, are likely vulnerable now, and SLR is expected to make them more vulnerable. There are few additional lands to develop here, and coastal use issues are focused on how to address non-conforming coastal structures.
- This area connects both sides of Cape Cod. It is in a low area, and therefore subject to flooding.
- The roadway is vulnerable to erosion and SLR impacts. The road is currently maintained through replacement of sand. Without continued replacement, the road would likely be lost. The steep area just south of this area supplies sand for other areas via erosion.
- Area of concern due to the occurrence of overwash in the past. The NPS has a restoration project in this area that it has started work on.
- The coastal area will probably not be breached as a result of SLR. Sea level rise will increase rate of erosion on the bluff, but the waves will continue to form barrier beach. This area is vulnerable to over wash, and will likely be more vulnerable over time. Notes: Alterations to the roadway, Rte 6 or 6A, could help head off environmental problems. The road to the north of this area has a dike, so it is no longer a natural tidal system. The dike at this location would need to be opened to allow flow between the fresh and salt water side to maintain a natural tidal regime.
- The golf course is already below sea level, and is often flooded from ground water.
- The area is located at low elevation and is vulnerable to SLR impacts from ground water elevation.
- Mayo Creek. The most dense part of the town is at a very low elevation and is likely vulnerable to SLR.
- Blackfish Ceek Highway is diked across the marsh and is vulnerable to SLR.
- Highlighted area could be considered example of "passive adaptation." Lieutenant Island Road, the road out to the island, is closed twice a day at the high tides. Residents have dealt with the road closures for many years.
- Example of long engineered shoreline. Erosion is a problem along the bay. There is a large concentration of homes in this area, and many have seawalls. The beaches are replenished with sand in order to maintain the area. Harmes Way could collapse in on itself. The area has been eroding for many years and is an example of sediment mismanagement. Various erosion control structures in the area have stopped the sediment supply and, as a result, it is rapidly changing. Coastal structures are still allowed to be built in the area, but property owners are required to replenish the sediment in front of the structures. As sea levels rise, it might become difficult to keep up with sediment replenishment levels.
- A, B, and C: These three areas are in a low-elevation marsh system. There is a need to confirm the elevations on these roads.
- This stretch of Route 28 in Orleans just before the Harwich line has had erosion issues during large storms.
- Route 6 crosses a low marsh area. The bike path is also in a low-lying area near the marsh.
- This area is a low-elevation area where SLR could become an issue, especially if anything happens to the coastal barrier.
- If the current Chatham fish pier is no longer viable as a port, this area would presumably become the location of the new port system.
- The coast is not eroding right now, but the area to the east is no longer a barrier beach. Due to a storm, there is now an inlet and the area to the south is an island. The area is now dissipating fairly rapidly; presumably there will rapid erosion as that island continues to dissipate. An area to the north is armored, but it is not sustainable. The entire shore will likely be cut a lot, and in the future the inner shore will be the outer beach. This probably will not happen for at least 10 years. Note: Economic activity at the Chatham fish pier will likely be impacted by changes in this area.
- The beach is eventually going to close in. It is a very low-elevation area. The harbor will likely be closed as the beach washes in. The entire area is vulnerable to SLR impacts and changes that will result with the beach is gone.
- The road is at low elevation within tidal marshes. There are not issues with the area currently, but as the sea level rises, it could become prone to flooding.
- A: In Harwich, the ponds and estuaries are small and do not go in very far upland. This area is more subject to storm damage and hurricanes. In terms of SLR, the southern shore's elevation would be a concern. Flooding will likely become worse as SLR occurs. When the two harbors eventually connect will there likely be new flooding areas.
- B: SLR will affect how far inland the flooding could go in this area and what happens to the barrier beach. As sea level rises flooding will likely occur more often in this area. The area at the center of the "hourglass" needs closer investigation. There are potentially many problem areas there.
- This area of Hyannisport is at low elevation. Existing flooding will likely occur more frequently as a result of SLR.
- A, B, C, D: Human management will likely dictate how severe SLR impacts will be here. Potential elevation issues with Route 6A need to be examined more. Right now, the road is fairly close to the water table, and thus could be impacted with even minimal SLR. Sandy Neck: If sediment can continue to deposit along Sandy Neck, then the area will likely be okay. Sandy Neck is still growing at the tip, but the impacts of the jetties, which disturb the sediment distribution, is an issue that needs to be considered. If the beach here, which is currently narrow, goes away completely, erosion rates will increase. The sediment has been built up over a long period of time. However, interruption to the sediment flow, which has been going on for 100 years or so, is causing the beach to thin. With higher storm surges, issues for marsh viability could be created. This area has the potential for a large scale rapid environmental change. USACE could consider reviewing its dredging management policies for the canal.
- The main road in Falmouth is at low elevation. The Great Pond Bridge and "fingers" of land in Falmouth are vulnerable to SLR, likely on the 40-50 year time horizon.
- The entire Woods Hole area is at low elevation and vulnerable to flooding. The effects will likely be worse as SLR occurs.
- The bridge being rebuilt here has a lifespan of 75-years; yet, the road beyond the bridge is vulnerable to erosion and is expected to be eroded away in approximately 50 years (In some places, Chapoquoit Road is already falling into the shore).
- This area has a much higher potential for flooding due to the effects off of Buzzards Bay.