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Erosion-Presentation.pptx
- 1. Lauren Hunt, Christopher Sample, Kathleen Sullivan December 16th, 2014 Project Sponsors: Jeff Carlson, Peter Morrison, and Mary Wawro Project Advisors: Dominic Golding Stanley Selkow
- 2. Overview -What is Erosion -Objectives/Goals -What we did and how we did it -Findings -Conclusions and Recommendations
- 3. Defining coastal erosion is rather straightforward Understanding coastal erosion is not as easy What is Erosion?
- 5. Why is erosion an issue? Threatens 300,000 homes Destroys 1,500 homes In Nantucket 2 feet to 12 feet a year Sheep Pond Road Area 5 houses lost 10 Houses relocated
- 6. Goal Evaluate the current condition, impacts, and effectiveness of the coastal erosion structures
- 7. Limitations -No universal rating scale -Erosion rates from aerial photos and CZM transect lines -Structures which have permits -7 weeks of onsite visits
- 8. Objectives Categorize Data Variety of structures and methods Evaluated impacts and effectiveness Breakdown of Opinions Coastal erosion practices and policies Island stakeholders Create Recommendations Future Policies Erosion control strategies
- 9. Erosion Structures • Seawalls • Groins • Geotextiles • Offshore Breakwaters Hard • Beach Nourishment • Vegetation • Sand Fencing • Jute Mesh and Bags Soft
- 10. Permitting Process Design Resource Areas Impacts Notice Of Intent Public Hearings Approved Denied Order of Conditions Withdrawn
- 11. What we did -Site Visits -Google My Maps -Database -Effectiveness Rating Scale
- 12. Site Visits Located Structures -Aerial photographs -CZM database Documented -Notes -Photographs Post evaluation notes
- 13. Google My Maps
- 14. Database
- 15. Good •2 Points Fair •1 Point Poor •0 Points Structure Test Property Test Beach Test Total Score 0-6 5 or 6 •Effective 3 or 4 •Adequate 0 to 2 •Ineffective Effectiveness Rating Scale Structure • Integrity • Condition Property • Scouring • Holding back land Beach • Beach present in front of property
- 16. Findings Types of Structures Hard Soft 42% 58% Location of Structures Northwest Siasconset South Harbor 69% 17% 7% 7% Effectiveness Rating Scores 5 to 6 3 to 4 0 to 2 50% 44% 6%
- 21. Soft Structures Pocomo Road Coskata Course Way Now more likely to be permitted by Conservation Commission -Sand fencing -Jute mesh and bags -Sand nourishment -Beach grass plantings
- 22. Lauretta Lane
- 23. Stakeholder Perspectives Natural Resources Department Nantucket Coastal Conservancy Josh Posner, President SBPF John Merson, Baxter Road resident
- 24. Conclusion -Location of Structures -Type of Structures -Difficult to evaluate effectiveness
- 25. Conclusion Soft structures may -Decrease erosion -Encourage accretion -Require more maintenance Hard structures may -Protect land behind them -Cause scouring -Distant impacts
- 26. Recommendations Continue to inspect structures -function as expected -limit unauthorized Update and maintain database Maintain systematic photographic record
- 27. Recommendations ConCom continue to work with homeowners Develop systematic approach to evaluate effectiveness
- 28. Acknowledgments A special thanks to: Jeff Carlson and all of the Natural Resources Department Sheila Lucey the Harbor Master Mary Wawro and Peter Morrison Harvey Young and Young’s Bicycle Shop Andrew Mckenna-Foster and the Maria Mitchell Association And to all those that have taken the time to talk with us
- 29. Questions and Comments -Created database of 72 structures with 20 fields of information -32 Effective structures, 36 adequate structures, 4 ineffective structures -Recommend the town maintains database with all current and future structures -No cookie cutter way to signify one structure is better than any other, effectiveness will vary by location due to outside impacts -Recommend future evaluations of effectiveness
- 33. Quaise Road
Editor's Notes
- Define Coastal Erosion The loss of sand from beaches and dunes into offshore sand system Understanding it is a different story Many factors involved including wind water and other natural forces
- Coastlines are in a constant dynamic system This is shown in the map from the coastal zone management morris mapping tool. The lines show the high water shorelines from 1884 to 2009 This is eel point out on the northwest tip of the island
- To fulfill our goal our project had three major objectives The first it to categorize and collect data on erosion structures on the island. We had to collect information on all the structure, evaluate it, and perform a preliminary evaluation of effectiveness and impacts. The second is to gather information on the opinion on the island. We interviewed Island stakeholders to gather opinions on Coastal erosion Practices and policies. The third and final objective was to create a set of recommendations for future policies and erosion control strategies
- Before we began to go out and look at any methods used to mitigate erosion we did research on the different types of structures used They can be broken down into two different categories, hard and soft structures. Hard structures focus on solid objects to protect the shoreline while soft structures focus on more natural approaches to stabilize the shoreline. While we can define hard and soft structures most erosion structures implemented use a combination of a mixture of methods as an erosion structure. So when we refer to a structure as hard or soft we are referring to the primary component of the structure
- To locate the structures on the island before we went out we utilized aerial photographs and the Czm database of erosion structures. This helped us locate stretches of shoreline and a list of locations to visit. During each visit we documented the trip with notes and photographs and then wrote up post evaluation notes when we got back from a trip
- To organize the photos we took we utilized the function of a google my maps application. This allowed us to create markers for each erosion structure we visited with photos and a quick description of both. The points are organized by map and parcel number. They are further organized by location. Northwest, harbor, siasconset, and the south shore. A helpful function of this application is that you can compare an aerial photograph of the structure with actual on ground photos of the structure
- Stretch of groins just inside the Harbor. Historical photographs. 1995 you can see the shoreline staggered along the groins 2014 the shoreline extends past the groins and to the right there is a large accretion of sand This may be a result of the instillation of the groins or just a result of natural accretion
- While visiting different site we noticed a pattern in structure more recently built and permitted. These are soft structures that include….. These structures are more environmentally friendly and are designed to work with the environment to stabilize the slope and toe of a bluff.
- While these structures are considered soft they can also have similar effects to a hard structure. One of these structures is located at lauretta lane. This is a fence with jute filled bags behind it. These jute bags are so tightly packed with the fence that it doesn’t allow for any transport of material from the bluff to the beach in front thus creating a situation similar effects of a seawall. While we noticed this observation here many other similar structures did not have this effect.
- Location location location