Living Shoreline Fundamentals

Transcription

1 Living Shoreline Fundamentals Karen Duhring Virginia Institute of Marine Science College of William & Mary April 19, 2017 Kilmarnock, VA

2 Living Shoreline Fundamentals Origins of Living Shoreline Initiative Main Guiding Principles Project Type Examples Professional Service Needs & Opportunities

3 ORIGINS OF LIVING SHORELINE INITIATIVE

4 Cumulative Impacts of Shoreline Hardening Combined effects of multiple projects on habitat & water quality even where shoreline hardening is absent Rappahannock River

5 Cumulative Impacts of Shoreline Hardening Habitat loss & fragmentation Decreased habitat diversity Altered sediment supply & transport Increased scour & turbidity Fewer fish & shellfish Decrease in marsh bird diversity Wetland migration interrupted Increase in invasive species National Research Council 2007 Evidence of low thresholds Some adverse effects 5% hardening Easily found when hardening reaches >15% of shoreline Download free PDF

6 Shoreline Hardening Northern Neck - Middle Peninsula VIMS Inventory Date Bulkhead miles Revetment miles Combined % shoreline surveyed Westmoreland % Northumberland % Lancaster % Middlesex % Mathews % Gloucester % Richmond Co % Source: VIMS Comprehensive Coastal Resource Management Plans

7 Origin of Living Shorelines Not New - Vegetative Stabilization developed in 1970 s Always preferred alternative for low energy, minor erosion problem solving but not widely practiced 2004 new initiative started in Maryland & Virginia to re-invigorate interest in low impact stabilization Fueled by data from cumulative impact analyses & scientific research of hardened shorelines Annual miles of shoreline hardening Net tidal wetland loss compared to mitigation acres Re-Branding with Living Shorelines

8 Coastal States with Living Shoreline Programs due to concerns for shoreline hardening trend Northeast Connecticut Rhode Island New York New Jersey Delaware Mid-Atlantic & Southeast Maryland Virginia North Carolina Florida Gulf Coast Alabama Mississippi Texas West & Northwest California Oregon Washington Great Lakes Michigan Ohio New York Many outreach education resources & new incentive programs now available

9 Virginia s Living Shorelines Initiative Recent Accomplishments Legal definition & stated preference VMRC General Permit Group 1 effective September 2015 Group 2 in progress New Nationwide Permit 54 Living Shorelines US Army Corps of Engineers, Norfolk District New Funding Support Programs Chesapeake Bay TMDL Credits protocol in progress VIMS Shoreline - Tidal Marsh Inventories & CCRMPs 26 localities now complete VIMS Design Guidelines update in progress

10 Northern Neck Middle Peninsula Living Shorelines Support Network Shoreline Erosion Advisory Service Local Governments Many Local Professionals

11 Living Shorelines MAIN GUIDING PRINCIPLES

12 What are Living Shorelines for Erosion Protection? Alternatives for bulkheads & revetments Where erosion cannot be tolerated & some type of shoreline management is necessary Nature-Based Features Mimic &/or protect existing local habitats Upland Riparian Buffers Wetland Tidal Marshes Sand Beaches Shallow Water Shellfish Reefs Submerged Aquatic Vegetation SAV

13 Upland Bank Erosion Erosion area above intertidal zone

14 Living Shorelines for Upland Bank Erosion Create more gradual slopes Create distance that waves must cross before striking shoreline Bank Grading + Sand Fill + Planted Marsh + Marsh Edge Protection Graphic Source: Chesapeake Bay Foundation

15 Marsh Edge Erosion Erosion area within intertidal zone Salt Marsh

16 Living Shorelines for Marsh Edge Erosion Help stabilize erosion & increase vertical sediment accretion Natural marsh shoreline Living Shoreline Treatment Graphic courtesy of the Partnership for the Delaware Estuary & DNREC

17 What s the Difference? Habitat Restoration Wetland Mitigation Main purpose is to create & replace lost natural habitat for its intrinsic value Human presence minimal if not absent to protect ecology Living Shorelines Main purpose is usually to solve a problem for people using organic techniques Manipulated, engineered designs Human presence normal water access, recreation activities Change the physical forces, ecology evolves over time eventually mimic but not always match natural habitat Vital habitats in developed estuaries

18 Common Elements in Living Shoreline Definitions Erosion risk reduction unacceptable erosion risk is present and some type of shoreline management action is necessary Wave attenuation rough surfaces to reduce wave height and energy of approaching waves Habitat heterogeneity Diverse habitats similar to natural shorelines in local area; living habitats are dominant features Habitat continuum unimpeded migration of fish and wildlife along the shoreline and between aquatic and terrestrial habitats, flow of energy, organic matter, & food between habitats Habitat dynamics & migration habitat features can shift in response to sea level rise, vertical sediment accretion Source: Bilkovic, Mitchell, Mason & Duhring 2016

19 Achieve Ecological Uplift Net Benefits B. Burton DNREC Reduce erosion but also. Net increase number & types of fish and wildlife Do No Harm to ecologically valuable habitats Connect animals to critical nursery areas Less constraints, dynamic sand & soil movement Habitat tradeoffs are one focus of permitting process

20 MOST SUITABLE Upper reaches of tidal creeks Where are living shoreline methods suitable? Least Suitable Bayfront & main tributaries Ocean coast MAYBE Lower reaches, wider creeks

21 Storm Performance - Realistic Expectations Living shorelines are usually submerged during storm events Impact on waves is much less when water depth exceeds plant height B. Burton Hull Springs living shoreline project during Veterans Day Nor Easter 2009

22 Living Shoreline Resilience Post-storm recovery is expected after multiple events Same planted marsh the day after Hurricane Irene 2011

23 Shoreline Erosion vs. Tidal Flooding Erosion protection structures typically cannot reduce flooding risk Different adaptations for flooding Elevating houses - roads - utilities Fill material to raise elevations Retreat from shoreline

24 Other Limiting Situations Living Shorelines are Not Appropriate or Feasible Everywhere No need for risk reduction Overwhelming need for risk reduction more substantial level of protection required Significant or critical resources would be harmed Nature-based features cannot be self-sustaining Costly & frequent inputs needed to persist Overwhelming construction access challenges Necessary equipment cannot gain access

25 Site-Specific Design Required Every site has unique set of circumstances Physical & Biological Human risk situation & perceptions Potential use conflicts Navigation, recreation access Potential changes to adjacent shorelines Sediment transport, reflected wave energy

26 Must Consider Both Direct Cost Comparisons & Long-Term Co-Benefits Direct Costs Design & permitting Demolition & site prep requirements Sources & transporting materials Available labor Troubleshooting until self-sustaining establishment Long-term maintenance Co-Benefits Property value increases Storm damage reduction Seafood production Nutrient reduction Sediment accretion Carbon sequestration Biodiversity & more Collaborative Performance Monitoring to document these values in progress

27 Living Shorelines - Main Guiding Principles Review Nature-based techniques to solve problems Based on landowner needs & interests Achieve net ecological uplift Storm surge flooding not prevented, but resilient & selfsustaining over time Not appropriate or feasible everywhere Site-specific design considerations required No standard recipes or one size fits all site designs Both short- and long-term costs & benefits should be considered & monitored for adaptive management

28 PROJECT TYPE EXAMPLES

29 Living Shoreline Project Types Non-Structural Bio-Based Vegetative Stabilization Sand Fill Gradual Slopes Some of these may qualify as Group 1 General Permit projects Hybrid Engineered structures required to support living habitat components & achieve desired level of protection

30 Riparian Buffer Enhancements - Vegetation Waterfront lawn conversion Native plant gardens Invasive species removal Selective tree pruning Selective tree removal Dead, dying, severely leaning New demonstrations at Hull Springs & Capt. Sinclair M. Ross

31 Riparian Buffer Enhancements Stormwater Management Divert runoff away from top of bank Downspout disconnects Better vegetation buffers Create steps or terraces Steps from parking lot at Reedville Living Shoreline

32 Before Bank Grading & Riparian Buffer Planting During After Allows for wave run-up Better vegetation growing conditions with less slipping & soil movement Highbank, White Stone JPA #

33 Coir Logs + Sand Fill + Planted Tidal Marsh JPA # Mathews Co.

34 What to Expect with Coir Logs 2013 Temporary containment of sand Gradual coir log bio-degradation Marsh expansion

35 What to Expect with Coir Logs Planted Tidal Marsh Planted marsh persists after coir logs disappear Property owner acceptance & understanding for taking care of marsh Deltaville Yachting Center +7 yrs. JPA #

36 Filtrexx GroSoxx Geotextile products designed to promote vegetation growth Filled with compost & sand Stacked & staked against bank Planted with marsh grasses Urbanna Town Marina JPA #

37 Marsh Sill A low-profile revetment backfilled with sand to create & support planted tidal marsh Planted Tidal Marsh Stone Sill Hull Springs JPA #

38 Typical Marsh Sill Construction Sequence 1. Filter cloth placed 3. Settling period monitor tide levels 2. Sand fill for access & stone sill 4. Plant tidal marsh vegetation Photos courtesy B. Burton, Longwood University-Hull Springs project

39 Hull Springs Living Shoreline +3 yrs.

40 Hull Springs Living Shoreline +7 yrs. Marsh ecology develops over time 5-10 years

41 Hybrid Structures Performance Tracking Are they achieving ecological uplift? Structural integrity & position changes Tidal ebb & flood patterns Effects on planted marsh New tidal channel formation Fish & wildlife marsh access All life stages JPA # Milford Haven What s living on & between the rocks compared to what s covered Sediment transport & accretion effects especially at marsh spit features JPA # White Stone

42 Shellfish Reef Structures or Biogenic Reefs Mimic natural marsh shellfish association Intercept wave action with reef-like structure Provide similar habitat & water filtering services Compliment shellfish restoration goals Ribbed mussels & Spartina alterniflora VIMS Teaching Marsh

43 Oyster Shell Bag - Marsh Edge Protection Oyster shell bags placed along eroding marsh edge Johns Point Landing, Gloucester Co. JPA # years 3-D growth of new oysters splitting bags open

44 Oyster Shell Bag Sill with Sand Fill & Planted Marsh Pyramid stacked bags in this case for 2.5 ft. tide range Sand fill to raise elevation for planted marsh &/or allow existing marsh to expand Hopkins et al Gloucester Co.

45 Biogenic Reef Products Oyster Castles

46 Biogenic Reef Products

47 Biogenic Reef Products

48 Coir Log Reinforcement with Oyster Castles & Oyster Shell Bags DNREC Delaware Estuary, New Jersey

49 Biogenic Reefs Performance Tracking Are they achieving ecological uplift? Long-term reef performance & evolution still under investigation Initial evidence - good recruitment & habitat for diverse species where natural spat set also present Adequate wave attenuation & protection for adjacent marshes? Solving erosion problems?? Fate of polyethylene plastic with additives for UV protection microplastics Compatibility with regional oyster restoration goals not yet determined

50 Offshore Breakwaters with Beach Nourishment & Dune Planting Expand existing sand beaches for wave attenuation & erosion protection Breakwater structures strategically placed to maintain wide pocket beaches Diverse habitat areas persist in higher energy settings JPA # VIMS Beach, Gloucester Point

51 Wave Attenuation Structures for higher energy sites Non- Destructive Destructive Wave energy Wave Attenuation Device (WADs) Sediment Accretion Photos LSS & Mid-Atlantic Environmental LLC Courtesy D. Janiec JPA # Cape Charles

52 Wave Attenuation Structures for higher energy sites S. Lindsey JPA # Ingram Bay

53 2007 Greening Up Hardened Shorelines Deltaville Maritime Museum Living Shoreline 2009 Failing timber bulkhead Sand fill + fiber logs Planted tidal marsh tied into existing marsh Pine tree limb removal JPA #

54 Greening Up Hardened Shorelines Marsh Sill + Planted Marsh in front of 2 defended shorelines VMRC

55 PROFESSIONAL SERVICE NEEDS - OPPORTUNITIES - RESOURCES

56 Professional Service Needs & Opportunities Site Selection Design - Construction Recognizing suitable sites & situations Concept designs Permit applications & coordination Construction management Sub-contractors B. Burton Special equipment & materials Horticulture & landscape design partners Post-construction as-built surveys

57 Professional Service Needs & Opportunities Monitoring & Maintenance Short-term maintenance until establishment Regular inspections Look for & re-plant washed out plugs Monitor ebb & flood tides for scour & ponding Long-term monitoring & maintenance Provide assurance & document performance Periodic debris removal Storm damage assessments & repairs

58 Professional Support Resources The Contractor s Toolbox The Wetlands Project Demonstration Projects Reedville Teaching Garden Northumberland Co. Hull Springs Westmoreland Co. John s Point Landing Gloucester Co. Captain Sinclair Gloucester Co. VIMS Teaching Marsh & Beach Gloucester Co. Northern Neck Planning District Commission 5 new Lancaster Creek (2), Tabbs Creek, Corrotoman River & Hull Springs

59 Professional Support Resources Financial support programs VCAP Middle Peninsula Planning District Commission Permitting incentives VMRC electronic permit records searchable database VMRC Group 1 General Permit US Army Corps of Engineers Nationwide Permit 54 for Living Shorelines Design guidelines & assistance VIMS DCR Shoreline Erosion Advisory Service

60 Living Shoreline Fundamentals Summary National & Local Living Shoreline Initiatives Re-invigorate interest in nature-based shoreline stabilization Main Guiding Principles Solve problems for people with realistic goals & expectations Mimic dynamic natural habitats in local area w/ site-specific designs Expect habitat tradeoffs yet achieve ecological uplift Project Types Variety of techniques for different shoreline situations used alone or in combination Professional Service Considerations Meet growing demand for pre- & post-construction jobs Sub-contracting & partnering opportunities between landscape, design, build, & maintenance professionals Take advantage of support network & resources

61 Questions About the Fundamentals? Contact Information Karen Duhring