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HomeMy Public PortalAboutBCAG_Meeting1_SummaryFebruary 18, 2016 – Meeting Summary – Brewster Coastal Advisory Group 1 Brewster Coastal Advisory Group: Developing a Coastal Adaptation Strategy For Brewster Meeting One Summary February 18, 2016 | 5:30 – 8:30 PM Brewster Town Hall Room A&B | Brewster, MA Overview Considering future coastal change, sea level rise, and shoreline erosion, the Town of Brewster is supporting a public engagement process to develop a coastal adaptation strategy based on sound coastal science and public values and interests. The strategy will guide future decision- making in Brewster’s coastal areas. The Town of Brewster and its consultants, the project team, will develop the strategy through review of relevant scientific data and extensive input and guidance from the public and the Brewster Coastal Advisory Group. The project team consists of a public engagement team led by the Consensus Building Institute and a scientific and technical team led by Horsley Witten Group. The objectives of the first meeting of the Brewster Coastal Advisory Group were to: • Introduce group members, alternates, liaisons, and the project team to one another • Learn about the process, how the group will function, and how to participate effectively • Learn the fundamental concepts of shoreline science and the types of data used to analyze shoreline change • Discuss data collection and analysis and the final product. Materials reviewed during the February 18th meeting included: an agenda, tentative schedule and work plan, member list, and draft operating protocols. Presentations included an overview of Brewster’s coast, a presentation on coastal processes, erosion control structures and sediment budgets, and a sea level rise (SLR) and storm surge mapping presentation. Meeting materials and presentations, and a video of the meeting, are available on the project website: www.cbuilding.org/project/brewstercoast. Members present included: Abigail Archer, Ryan Burch, Matt Cannon, Ruth Courtnell, Tom Devane, James Goodrich, Claire Gradone, Howard Hayes, Kyle Hinkle, Bud Johnson, John Lamb, Chet Lay, Mary O’Neil, Donald Poole, Chris Powicki, Henri Rauschenbach, Jonathan Rice, Cindy Roth. The group made the following decisions at the meeting: • The group agreed to make decisions using the definition of consensus in the draft operating protocols. • The group decided that the technical team should start with visualizations of Crosby and Mant’s Landings and the full shoreline map of SLR, and then the group would decide which additional site(s) to visualize after reviewing this information. February 18, 2016 – Meeting Summary – Brewster Coastal Advisory Group 2 Welcome and Introductions Pat Hughes, Brewster Board of Selectmen, welcomed the group members on behalf of the Board of Selectmen and thanked them for their volunteer service. Her main points included the following: Brewster’s coastal areas shape the character and rural feel of the community, and are a significant driver of the local economy. This collaborative public effort to develop the coastal adaptation strategy is important because it will identify policy and actions that are appropriate for the coastal areas. And importantly, those policies and actions will be based on community interests and good science that helps us understand why and how the coast is changing. This group’s work is the first step toward the development of a coastal management plan that will define site-specific management actions tailored to the conditions at those sites. A Beach Access Survey was developed apart from this project. So far, 1800 responses have been collected and we anticipate the survey will provide good information about public preferences related to the coastal areas. The survey will close on February 26. Lastly, the group here represents a range of community interests and it will be important that we all work together for the community’s interest. Eric J. Roberts, facilitator from the Consensus Building Institute (CBI), led introductions and reviewed the agenda and meeting guidelines. For introductions, the group members formed pairs to discuss how they would define success for this project. A few participants shared their view of what success might look like. Their main points are summarized below: • We would gain consensus on what we face in Brewster in terms of climate change, shoreline change, and the science behind it all. We’d identify what we need to incorporate into a vision that will inform future decisions. • We would create a long-term view of beach needs and produce suggestions for manageable, affordable, and implementable actions that benefit the whole community. • We would have multiple interests represented, possibly find consensus on issues, and have a different type of process than has been implemented to date in the town. • We would have a plan that improves access to the beaches and mitigates erosion. Process Overview Carri Hulet, facilitator from CBI, reviewed and sought feedback on the draft operating protocols. Her main points included the following. CBI drafted the operating protocols to provide clarity on how the group operates. It describes overall participation; the role group members, the technical team, and the public engagement team; decision making; meeting guidelines; facilitation, and compliance with open meeting laws. Carri introduced the technical and public engagement teams, and the town representatives working with the project team. The town representatives include Pat Hughes (Board of Selectmen) and Chris Miller (Department of Natural Resources). CBI facilitators Eric J. Roberts and Stacie Smith lead the public engagement team and will facilitate the group meetings. They February 18, 2016 – Meeting Summary – Brewster Coastal Advisory Group 3 have no decision-making authority and will work neutrally to guide group discussions and ensure all group members have the opportunity to participate in the development of the final strategy. Mark Nelson and Geradline Camilli of Horsley Witten Group (HWG) lead the Technical Team, which also includes Mark Borrelli of the Provincetown Center for Coastal Studies and Stan Humphries of LEC Environmental. In response to a question about how the engineering team was selected, Pat Hughes said the town solicited HWG’s interest in working on the proposal after working with them on the town’s integrated water resource plan and being aware of other coastal work they have done. She added that HWG selected the other members of their team. Carri read the decision-making process outlined in the draft operating protocols (see page 3 of the operating protocols) and sought feedback and clarification about the process. In response to a question about past success using this approach, Carri responded that CBI has been successful using the approach. She noted that if a group cannot reach consensus, then the group can decide to offer a range of options and the pros and cons of each option, as well as why the options are being considered, to accurately and fairly explain members’ differences. It would not be considered consensus if more people abstain from a decision than agree to it. A group member asked if the technical team meets outside of the group meetings and if the group members interact with them outside of the meetings. Carri responded that the technical team meets outside of these meetings, and the goal of the meetings is for the group to raise questions or ideas for the technical team to investigate. Most of the technical team’s work will be outside of the meetings. In terms of interacting with the technical team outside the meetings, group members can contact them directly or convey questions or concerns through CBI. Brewster’s Changing Shoreline Mark Nelson presented an overview of Brewster’s coastline (see slides at the Overview of the Brewster Coast link). His main points included the following: There are three main aspects of shoreline change to consider when developing the adaptation strategy: sediment movement, sea level rise (SLR), and storm surge. The Brewster flats are a unique geological feature that influence sediment movement and interaction with the shoreline. Comparing the normal high tide to the king tide is one way of visualizing the potential impact of SLR since we can expect that the water level of today’s king tide will become the normal high tide in the future. Storm surge can and has caused significant erosion and damage at some of the town landings; consequently, the town has implemented strategies to minimize this damage. During the course of this group’s work, we’ll learn about and consider how sediment movement, sea level rise, and storm surge will impact the town landings in Brewster to help develop the adaptation strategy. Group members asked the following questions or made the following comments. Responses are February 18, 2016 – Meeting Summary – Brewster Coastal Advisory Group 4 italicized: • We are looking at a 1.5 foot rise in sea level in the next 20-60 years? There are different scenarios that estimate anywhere from 1 to 6 feet depending on how much global ice melting occurs. • Will you be modeling the added effects of storm surge at different SLR scenarios? Yes, and we’ll discuss which scenarios you all think will be helpful. • Multiple members commented on the king tide: o It may be useful to look at an average of 10 years of king tide data instead of just one year due to variability in the king tide; does Brewster have historical data on king tides? The king tide varies year to year because it is based on the tidal cycle and alignment of the moon and the sun. Because of the variability, we’ll use scenarios to bracket the planning process. We’ll present tidal data that we have available from a tide gauge in Boston. We don’t have a tide gauge in Brewster but the tidal experience here is similar to Boston. o Is the king tide the lunar or the neap tide? It is the most biggest full moon high tide that happens once per year (of the 12-13 full moon high tides that occur each year) and is the result of the sun and full moon aligning. It can add 1-1.5 feet to the tide. • Are we not including Wings Island in the assessment? The group can decide if they want to include it or not; the map was only showing town landings with parking areas. • Do you have any statistics about monthly high tides and their correlation with storm surge? The presentations tonight do not include this, but high tide and storm surge are connected. We have a 10-11 foot tidal range here, and storms arriving at low tide are not problematic; however, storm surge arriving at high tide could add four feet to the tide level. Mark Borrelli presented information on coastal processes, erosion control structures, and coastal change and sediment budgets (slides at the Coastal Processes, Erosion Control Structures, and Sediment Budgets link). His main points included the following: Waves produce a lot of energy that moves a lot of sediment along the shoreline, which means the shoreline is always changing. The sediment moves as a “river of sand” in a zigzag pattern down the shoreline. The zigzag pattern is created because waves crash on the shore at an angle, but retreat from the shore in straight line. The process of sand moving due to the wave action is called Longshore Sediment transport. Longshore Sediment Transport can move approximately 500,000 cubic yards of sand down the shore in a year. Or, another way to think about that amount is that 500,000 cubic yards of sand would equal 137 dump trucks loaded with sand rolling down the beach each day. Cross-shore Sediment Transport is the process of sand moving on and off the beach and is most apparent by viewing the beaches in different seasons. In the summer time, fair weather waves push sand onto the beach and the beach area grows wider. In the winter, waves pull sand off the beach and the beach area becomes narrower. At the same time the sand is pulled offshore in the winter, it creates a sand bar in the water that then protects the beach from the wave February 18, 2016 – Meeting Summary – Brewster Coastal Advisory Group 5 action and reduces erosion (This is the normal process with a beach adjacent to open ocean. In the Brewster, much of the sand pulled off the beach is deposited on the flats and a bar isn’t created.). This flux and movement of sand is a state of dynamic equilibrium. Natural beaches in the optimal state of dynamic equilibrium exhibit the seasonal changes caused by cross-shore sediment transport. Beaches must be dynamic to be in equilibrium. If bluffs are protected to eliminate erosion, the dynamic equilibrium is disrupted and eventually the sand will disappear from the system. Coastal strategies often include erosion prevention structures such as groins, jetties, and seawalls yet their use presents several pros and cons. Structures to prevent erosion can be considered erosion relocation structures because they trap sand in one area and causes sand to be eroded from another area. Consider a groin’s impact on longshore sediment transport: the groin serves as a dam that blocks the river of sand moving down the shoreline. Sand is captured on the up-drift side of the groin, while the down-drift side of the groin is starved of sand which leads to the erosion of sand on the down-drift side. The groin field creates a zigzag beach profile because they affect where the waves crash on the beach and where sediment is deposited or eroded. Jetties have a similar impact to groins. Seawalls completely disrupt the dynamic equilibrium; if seawalls are installed, eventually the sand will disappear. Mark Borrelli created a sediment budget for Brewster’s coastal areas to show how much sand is entering and leaving the system. Much like a household budget measures money earned and spent, the sediment budget identifies where the sand is coming from (a source) and where it is being deposited (a sink). In scientific terms, the combination of a source and a sink creates a littoral cell. By comparing two surface elevation models, one created with 1930’s bathymetric data and another with recently collected LIDAR data, Mark determined how much sand has moved and how it has moved since the 1930s. Mark clarified that the 1933 data is remarkably accurate due to the amount of data points and the consistency with which the data was collected. The budget shows the amount of sand that has eroded or accumulated across a series of transects. For example, a ½ mile transect of Brewster’s beach shows that the difference between the 1930’s data and the recent LIDAR data is approximately 7-9 feet of erosion. In response to a question, Mark said they could quantify dune erosion rates and that he estimates the erosion from the dune is minor. He added that most of the sand movement in this particular transect is related to longshore sediment transport. In another transect, 5-6 feet of sand has accreted to create a sand bar. In yet another transect, it appears that a massive sand bar of 10-12 feet in depth is forming; this is an area near Brewster that acts as large sink. He noted that a transect could be considered accretional even if the beach itself is eroding; in this instance, it may be accretional because more sand is being deposited offshore in the water than is eroding from the beach. Overall, the budget shows that sand is moving west to east. The sand is eroding from approximately Nobscusset Point in Dennis to just east of Quivet Creek. The beach is relatively February 18, 2016 – Meeting Summary – Brewster Coastal Advisory Group 6 stable from just east of Quivet Creek to approximately Ellis Landing. The beach is accreting from just west of Ellis Landing to Skaket Beach in Orleans. A lot of the sand in this system stays in the system, but ends up in the offshore sink located east of Brewster. It will be useful to consider how the different areas of the beach are accreting or eroding as the group starts to think about strategy recommendations. The takeaway message is that when considering how to create a strategy, we must look at the whole coastal system (the sand on and off shore) and not just the tiny sliver of sand we normally think of as the beach area (the area between the water line and the parking lot or upland area). The tides, the winds, the waves, storms, etc. all converge to create, change, and recreate the beach. Conducting beach nourishment on a little strip of beach every so often will not change or stop all the other variables that create the beach; the beach will continue to change because it is part of a larger system. Although we cannot change the way the sand moves, knowing about the dynamic equilibrium of a beach and understanding how a beach evolves can help us to set better expectations about how our management actions will or will not impact the beach. Members made the following comments: • Are we seeing two different things or the same thing between the longshore sediment transport that we see adding sand to the sink off the coast and the things we see happening to town landings onshore? It is all the same system. But, the system is not building dunes as fast as it is eroding them at this time. We are more conscious of the dunes eroding because we see the impact, but that impact is only a minor fraction of the total amount of sand that is moving around in the system. • How does the sand building up off the coast impact the shoreline? If you have a sand bank off the coast, will it make water come further onto the beach and erode more of the dunes? Wave energy is what causes erosion, and the flats in Brewster protect the shoreline by limiting the size of the waves and reducing the wave energy reaching the beach. • Did the sediment study account for variations or patterns in erosion and accretion in areas that are not steep versus areas that are steep, which might help us focus attention on areas with high erosion? The sediment budget study didn’t look at this, but this project can look at the sediment budget data, the state and federal shoreline change figures, in addition to what structures are out there, to take that into account. • What is the net loss of sand in the system to the ocean depths and can we look at that? The amount of sand reaching the depths is limited here due to the low energy waves; most of the sand is kept here due to the flats. Maybe less than 5% of the sand is lost to the ocean depths. Data Collection and Methodology The technical team will create several different products to inform group discussion and recommendations for the strategy. These products will include a map of Brewster’s coast that February 18, 2016 – Meeting Summary – Brewster Coastal Advisory Group 7 illustrates inundation and shoreline levels under various SLR scenarios, and visualizations of 2-3 landings to illustrate how SLR and storm surge will impact those landings. Mark Nelson presented on sea level rise and storm surge, and some of the other data points that can be used to understand the shoreline.Main points from his presentation included the following. (For more detail, see the slides titled Sea Level Rise and Storm Surge Mapping). The technical team will create a shoreline change map of the entire town of Brewster to show how the coastal areas are changing overtime. Based on historical shoreline changes, the map will try to give the best estimate of the shoreline’s location in 20 or 60 years. Shoreline is defined as the wrack accumulation line (wrack consists of items (wood, kelp, trash, etc.) from the open oceans that are deposited on the shore) and usually marks the high tide line. From a planning standpoint, this map will help to understand where beaches are eroding or accreting. Estimating the dune line is much more difficult to complete. Estimates of SLR in Brewster will be based on an inter-agency report developed by the National Oceanic and Atmospheric Administration and linked to tide gauge data. The scenarios estimate levels of SLR due to the rate and amount ice melting and increasing ocean temperatures. This group will need to determine which scenarios to use. The scenarios will be examined with tide gauge data (most likely from the Boston Harbor gauge) to create maps showing the possible range of SLR. The technical team would recommend the group look at 20 and 60 year planning horizons; this would provide a range of SLR scenarios in the intermediate/middle-of-the-road level. Storm surge modeling illustrates how the tides and storms interact to push additional water onshore during a storm event. Estimates of storm surge will be modeled and mapped using the Sea, Lake, and Overland Surges from Hurricanes (SLOSH) model. The SLR data and SLOSH storm surge data will be combined to visualizations that show what we might be able to expect in the future. Two or three visualizations at town landings will be created. The technical team recommended creating visualizations on both the western and eastern ends of the Brewster coast. Mark presented an example visualization for Paine’s Creek showing current water levels, high-tide level at February 9, high-tide plus an additional foot from SLR, and high-tide plus an additional 2 feet of SLR (the example did not include storm surge). A member noted that the visualization is also comparable to the current high-tide with a 1-2 foot storm surge added. Mark noted two caveats about the visualizations: 1) the visualization does not include storm surge, and 2) the visualization uses the current landmass, but the landmass is likely to change with increasing water levels. The maps will help the group to prioritize recommendations by visualizing what could happen in various locations. The group discussed where to complete the visualizations. Several people supported the idea of creating visualizations on the East and West ends of Brewster’s coast, and many suggested completing a visualization in-between the western and eastern visualizations. February 18, 2016 – Meeting Summary – Brewster Coastal Advisory Group 8 The group offered several criteria for picking the additional location to visualize, if the budget is limited to 2-3 visualizations: • Town and state property locations: Visualize sites where town-owned land is located behind the site (which would allow for migration) or where town and state owned land may be impacted. • Freshwater resources: Look for areas with freshwater wetlands for the middle visualization. • Stability of an area: Consider areas that are stable or that are eroding. From one person’s perspective, west of Point of Rocks to Breakwater tends to be the most stable portion of the coast. Some members said they thought that most coastal erosion is occurring east of Ellis Landing in east Brewster. • Real estate impacts: Look at the concentration of property that could be impacted and changing coastline conditions to identify the middle visualization. • Parking availability or use: Consider selecting the site based on the number of parking spaces available at the sites, or concentrate on the most heavily used sites. Saint’s Landing, Ellis Landing, and Crosby landing were suggested as the landings with the most parking spaces. • Higher bluff areas/less vulnerable to overwash vs. Open, flat areas that are more vulnerable to overwash: The area between Ellis Landing and Point of Rock is an area of high bluffs with stone walls, while Breakwater and Little Breakwater are flatter and more open. Mark Nelson said impacts may be more likely in areas where the elevation is lower (such as Breakwater) and that the lower elevation areas such as Paine’s Creek, Breakwater, and Mant’s landing have been overwashed in past events. • Environmental conditions: This could include whether or not an area is high bluff or open and flat. Mark Nelson noted that more impact may be seen at areas where elevation is lower. Other considerations include whether or not erosion control structures are already in place. • Map the whole shoreline first, then identify impacts and decide which areas to visualize. It was suggested that the technical team model all town landings. Mark Nelson noted that the budget currently allows for 2-3 visualizations but they could talk with the town about completing others too. He added that if the visualizations are easily completed then they might be able to do more than the initial 2-3 sites. He said the town will own the data and be able to use it to visualize other locations in the future, if desired. He suggested that the town-wide map of estimated SLR would provide guidance about what would happen at each town landing, and could be used to determine which additional sites to select. The group decided that the technical team should start with visualizations of Crosby and Mant’s Landings and the full shoreline map of SLR, then decide which additional site (or sites pending ability to do more) to visualize. A participant asked of erosion driven by overland runoff would be considered. Mark noted the sediment movement caused by overland erosion is likely minimal compared to the sediment moved by wave action. He suggested that the group could discuss how to address that if the February 18, 2016 – Meeting Summary – Brewster Coastal Advisory Group 9 visualizations show that type of erosion. The group identified the following additional questions and data to consider. Some points were provided via email after the meeting. Comments regarding the data or questions have been summarized with the appropriate topic. • Coastal terrain upland from the shoreline • GIS data including Digital Elevation Model (DEM) data; locations of freshwater systems; infrastructure including roads, drainage systems and stormwater infrastructure, utilities, etc; assessor's data by parcel including the acreage and the value of the land (to see the financial and spatial extent of impacts); and town-owned land and state-owned land (to help understand what the town has power over). Mark Nelson commented that some of this data already exists and can be easily included (e.g. inundation of wetlands connected to the ocean, town-owned or state-owned parcels), but some of it might be difficult to include. Including private properties and data related to them may raise other questions outside the scope of this work. • Clarity on how SLR will impact the Brewster Flats, including at low-tide. • Natural heritage and endangered species habitat data. • Review inundation maps that other groups created for various projects. • Historical data on the King Tides in Brewster. • Clarity on the types of tides the coastal areas experience. • Information about the Massachusetts Wetlands Protection Act to help understand what can or cannot be done. • Look at the tool from the "Getting to Resiliency" workshop or forum in Waquoit Bay. • Information about Wings Island, and the stretch between Wing's Island and Linnell Landing, and west Brewster in general. • Areas where people are already experiencing problems. • Wave-action impacts on top of surge and tide that cause coastal erosion and damage, and wave impact visualizations. • Effects of climate change on storm frequency/severity. • Mapping interventions of varying types to understand where and how frequently the following occur: beach nourishment, sturdy sand fencing, coir envelopes, jetties, revetments, groins, tidally restricted wetlands, etc. • Reports from neighboring coastal towns on Cape Cod Bay that describe their approaches or intended approaches to SLR and erosion (e.g. Dennis, Yarmouth, Orleans (for the Bay side), Barnstable, Eastham, etc.). Public Comment One member of the public spoke during the public comment period. Her key points included: Mark Borelli’s comment that the dune’s contribution to the accretion of sand in one area is minor made me think of two issues. First, what does minor mean--is this minor in the big picture or minor as in really tiny? Second, where are the lines that delineate the west, central, and eastern portions of the beach? February 18, 2016 – Meeting Summary – Brewster Coastal Advisory Group 10 Mark Borrelli responded to the first question. He said that it is minor amount from a geological perspective and in the big picture, but it is a big amount to a homeowner and for the beach itself. He added that removing even a little bit of sand from a system in near equilibrium can have an impact; the sand eroding from the dune is critical for the beach itself because it feeds the beach. Mark Nelson responded to the second question. Referring to the u-chart, he suggested the middle area is the area where the sediment is mostly stable. Mark Borrelli added that change seen on the shoreline may not be represented on the U-chart because the beach area of a transect may be eroding while the transect overall is accreting. Wrap Up and Next Steps The facilitators briefly reviewed and sought feedback on the schedule and work plan. Group members were asked to send questions, additions, and revisions to the workplan via email. Eric said the location of the visioning session is not set, and that all interested members of the public are welcome to attend and participate. It is hoped that the group members and liaisons also will attend. The goal for the visioning session is to better understand public interests and concerns so that the group can include those considerations in the final strategy. A member suggested avoiding May 6-7-8 since this is the week of Brewster in Bloom. Next steps: • The technical team will prepare the visualizations and town wide SLR line map for the next meeting. • Group members should review the summary to be sure your comments and questions were captured.