Sediment Management in the Coastal Bays

Transcription

1 Sediment Management in the Coastal Bays Introduction Need for ecosystem view of sediment management in Coastal Bays Island loss and restoration Navigation needs Habitat Trade offs Living Shoreline Requirements Background Barrier Island dynamics Goals Discussion Sediment Management Plan Navigation Committee Resurrection? Permit Streamlining?

2 Ocean City Feasibility Study 1998 Sand management plan to implement navigation improvements and restore fish and wildlife habitat Completed 1. Restoration of northern end of Assateague Island 2. Restore a total of 5 ha (12 ac) of salt marsh at the Isle of Wight Wildlife Management Area and 3. Restore a total of 3.4 ha (8.5 ac) of salt marsh at Ocean Pines,

3 Ocean City Feasibility Study 1998 To Be Done 4. Stabilize the eroding South Point Island to its 1997 size of approximately 0.93 ha (2.3 ac), 5. Construct a new 1.2 ha (3 ac) island in proximity to South Point to create vegetated habitat for colonial waterbirds, and 6. Create a 1.2 ha (3 ac) island near Dog Island that will be bare substrate with a shell surface for colonial waterbird nesting. The island created near Dog Island will also include three additional cells that will be available to local citizens, businesses, and government for the placement of material dredged locally. Thus, an additional 1.2 ha (3 ac) area of salt marsh will be added in the near future, and up to 8 ha (19 ac) area could eventually be created, increasing the size of this island to as much as 10 ha (25 ac).

4 Navigation and Dredging Advisory Group (NADAG) for Maryland s Coastal Bays (met initially Dec 1999, stopped meeting ~ 2003) Navigation and Dredging Planning Guide for Maryland s Coastal Bays edited by Cornelia Pasche Wikar Chair, Navigation and Dredging Advisory Group August, 2005 Recommendation: A.i.i. Support for and promotion of the beneficial use of dredged materials, including - habitat restoration and creation. - restoration of underwater grasses; - restoration of islands; - stabilization of eroding shorelines; - creation or restoration of wetlands; and - creation, restoration, or enhancement of fish or shellfish habitats

5 Beneficial Use of Dredge Material Beneficial Uses Introduction Decision Process Sediment Types Glossary Links References K-12 Lessons Lead Organizations Authorities Calendars Agricultural/Product Uses Aquaculture Construction Materials Decorative Landscaping Products Topsoil Maryland Case Studies Barren Island, MD Bodkin Island, MD Eastern Neck National Wildlife Refuge, MD Hart-Miller Island CDF, MD Kenilworth, MD Slaughter Creek, MD Twitch Cover Seagrass Plantings Engineered Uses Beach Nourishment Berm Creation Capping Land Creation Land Improvement Replacement Fill Shore Protection Environmental Enhancement Fish & Wildlife Habitats Fisheries Improvement Wetland Restoration

6 Sediment Sources Dead end canals Inlet, commercial harbor, Assawoman channel Source: COE 1998 North end of Assateague

7 Uses for sediments Stone sill View from pier looking south Isle of Wight marsh restoration using dredge material from the Assawoman channel

8 Uses for sediments Carlson (Thoroughfare) Marsh protection and enhancement behind low profile stone sills along high energy shorelines Assawoman Bay Sunset Island Marsh creation in low energy shorelines Herring Crk

9 Barrier Island Formation Source: Shifting Sands 2009 Chap 12

10 Barrier Island Dynamics Source: Shifting Sands 2009 Chap 12

11 Islands: Overlooked Coastal Landforms Island Formation: Mainland: high topographies and the degree to which sedimentation is able to offset submergence Back barrier islands washover fans, storm-surge platforms, old beach ridges, portions of flood deltas. Source: Shifting Sands, 2009 Chap 12

12 Source: Shifting Sands, 2009 Chap 12

13 Source: Shifting Sands, 2009 Chap 12

14 Former flood tidal delta Source: Shifting Sands, 2009 Chap 12

15 Sediment Distribution Based on Island Dynamics Source: Shifting Sands, 2009 Chap 12

16 Source: Shifting Sands, 2009 Chap 12

17 Sea Level Rise Potential mid-atlantic coastal landform responses to three sealevel rise scenarios. Most coastal areas are currently experiencing erosion, which is expected to increase with future sea-level rise. In addition to undergoing erosion, coastal segments denoted with a T may also cross a threshold where rapid barrier island migration or segmentation will occur. U.S. Climate Change Science Prog Synthesis and Assessment Product 4.1, Coastal Sensitivity to Sea Level Rise: A Focus on the Mid-Atlantic Region, 2009

18 Source: Sea Level Rise Response Strategy Worcester County, Maryland September 2008

19 Source: Sea Level Rise Response Strategy, Wor Co, MD 2008

20 Goals 1. Review and update extent of dredging needs 2. Identify/and Explore capabilities and opportunities for dredged material management 3. Engage user-groups and community in developing the Sediment Management Plan 4. Develop a Sediment Management Plan for the Coastal Bays 5. Establish a Committee to oversee, match and traffic sediments

21 Goals Con t The commission would navigate between 1) projects that generate sediments, such as navigation dredging projects; and 2) projects that require sediments such as various restoration projects (e.g. Skimmer Island other wetland restorations). Permitting should be streamlined. Specific projects such as the Skimmer Island restoration or Dog Island site would be set up, ready to accept sediments; with permitting requirements in place. That way, when a dredging job, either private or public, comes along, everything would be ready to go. The only thing needed is an assessment of the type of sediment being dredged, analyses including textural and chemistry. If the sediment is sand, then it s good for island restoration or beach replenishment; if it s fine-grained, then it s good for wetland creation or maybe island restoration.

22 Sediment Management Plans San Francisco Bay area Columbia River, Oregon Great Lakes, Jamaica Bay, Long Island, NY