Peter Slovinsky, Senior Geologist at the Maine Geologic Survey, is here to talk about the work that the Maine Geologic Survey has been doing to address coastal resilience.
Coastal resilience is the ability of a system to face adversity and bounce back from it. Achieving this involves evaluating vulnerability, identifying problem areas, generating solutions, and then implementing them. Working along Saco Bay with the towns of Saco, Biddeford, Old Orchard Beach and Scarborough, the Maine Geologic Survey has developed a series of tools for these towns do just that.
Historically Maine has experienced huge fluctuations in sea level. However, these fluctuations were the result of the earth surface rebounding as glaciers receded. Now sea level change is the result of global sea level rise. In Maine we have decided to plan for two feet of sea level rise over the next 100 years. This is a middle of the road estimate of sea level rise that might have to be revisited.
How is the rise in sea level going to affect the regulatory definition of coastal wetlands, that are defined by tidal elevations?
The Maine Geologic Survey started by looking at the existing conditions of the Scarborough Marsh system. Using LIDAR data they were able to map the existing conditions of the marsh and used these conditions as a baseline to predict the impacts of sea level rise on the area. They found that in areas where high marshes are adjacent to low lying land, two feet of sea level rise meant that the high marshes would transgress into the undeveloped low lying lands. Finding that this was really the only place for additional water to go the Survey suggested that the towns should begin preserving these undeveloped low lands as open space.
Such proactive measures are necessary given that the towns are already experiencing inundation problems. For example, there are areas where homes are located adjacent to low and high marshes "essentially mowing the marsh as there backyard." This means that these homes would be underwater in the event of a two foot rise in sea levels. By identifying areas where inundation may pose a problem towns can start thinking about relocating home, preserving open space for the high marshes to transgress without impacting infrastructure.
Things the Survey is encouraging the towns to be thinking about is: (1) what is going to happen in the future in terms of flood plains and (2) what is going to happen with regard to the health of our marsh systems.
Pete mentions that town should not be afraid to establish flood zones above and beyond FEMA standards, because flood zones established by FEMA are usually not large enough and courts have upheld these expanded flood zones.
So what needs to happen? Well, on the state level Pete says we need to redefine the definition of coastal marshes. While on the municipal level towns need to start setting aside lowlands adjacent to marshes as open space to allow for transgression of the marshes. Also, towns need to be adaptation to the Surveys findings by readdressing techniques for emergency access rerouting, stormwater improvements, building requirements, utility siting and by creating awareness (letting home owners know that they may be in a flood zone).
Finally what we are really focusing on is getting communities to think about future inundation and marsh transgression as a region, rather than as individual communities. Hazards, flood, etc do not follow geopolitical boundaries, so the long term goal should be to get communities to adopt regional plans.
Q: The best available science is a bit of a moving target, how do you balance starting to plan for sea level rise but also be able to adapt if the science changes?
A: My suggestion is that we revisit the science every ten, adapting our plan to any changes in available data.
Q: Your maps only focus on the front side, what does the back side look like in the face of a two foot sea level rise.
A: Unfortunately, we do not have the tool to be mapping the frontside, however we are starting to work with NOAA on a project that looks at the overall impacts of sea level rise.
Q: How have you been able to engage the communities?
A: This project started out with us sending out letters to the communities inviting them to participate, but also making it clear that in the end we expected them to make some policy changes. Then we held public meeting where we presented some of this information to community members. The next phase is to sit down with the town decision makers.
Q: Is there similar analysis being done up North, in mid-coast?
A: No our LIDAR data, which is necessary for us to be developing these models, is limited in scale. You need good topographical data and often where we get the photos from, NOAA and Army Corp, their interest tends to be the beaches. What we are trying to do now is to get the state to fund statewide LIDAR mapping which would allow us to be doing this analysis for other parts of the state.
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