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Managing Erosion on Estuarine Shorelines, by Spencer Rogers and Tracy E

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Managing Erosion on Estuarine Shorelines, by Spencer Rogers and Tracy E V PREFACE The estuarine areas of North Carolina are seeing with more proposals on the horizon. Sustainable use of these areas requires awareness, understanding and implementation of sound design and management options. The long-term environmental health of the land, water and natural resources will benefit the growing economy and quality of life. The N.C. Division of Coastal Management with North Carolina Sea Grant and the North Carolina State University College of Design developed The Soundfront Series, informational guides to assist property owners and community planners and managers. The guides are available in print and on the Web. The series includes: • Shoreline Erosion in North Carolina Estuaries, by Stanley R. Riggs. UNC-SG-01-11. Riggs is a distinguished professor of geology at East Carolina University. • Managing Erosion on Estuarine Shorelines, by Spencer Rogers and Tracy E. Skrabal. UNC-SG-01 -12. Rogers is North Carolina Sea Grant's coastal erosion and construction specialist. Skrabal is a senior scientist with the North Carolina Coastal Federation. • Protecting Estuarine Water Quality Through Design, by Nancy White. UNC-SG-01-13. White is an associate professor of landscape architecture in the College of Design at North Carolina State University. • Protecting the Estuarine Region Through Policy and Management, by Walter Clark. UNC-SG-01-14. Clark is North Carolina Sea Grant's coastal law and policy specialist. Lundie Spence, marine education specialist for North Carolina Sea Grant, and Bill Crowell, senior policy analyst of the Division of Coastal Management, served as coordinators and technical editors for the series. Katie Mosher, Ann Green and Pam Smith, all of the North Carolina Sea Grant communications team, edited the series. For information on the Division of Coastal Management, call 919/733-2293 or 888-4RCOAST. The division's Web site includes information on permits and regulations, as well as contacts for regional offices. Go to www.nccoasta/management.net. For information on North Carolina Sea Grant — and to order individual guides or the complete series — call 919/515-2454. Online, go to www.ncsu.ecfu/seagrant. Managing Erosion on Estuarine Shorelines TABLE OF CONTENTS Chapter 1: Introduction Chapter 2: Planning for Estuarine Shoreline Stabilization Options 4 Planning Considerations 6 Chapter 3: Estuarine Shoreline Erosion Causes and Effects 8 Erosion Causes 9 Tides and Weather 9 Chapter 4: Site Evaluation 12 Chapter 5: Options for Managing or Controlling Erosion 14 Land Management 15 Vegetation 16 Beach Fill or Nourishment 18 Shoreline Hardening 19 Sand Traps 25 Chapter 6: Regulations and Permits 28 Chapter 7: Resources 30 Pagel M a n a g i n g E r o s i o n Chapter 1: Introduction North Carolina’s estuarine areas As the demand for estuarine shoreline property owners understand various include nearly 4,500 miles of estuarine and property rises, the value also increases. options. A more comprehensive discussion ocean shorelines, and more than 2.1 million Thus, landowners become concerned about of erosion is found in the companion North acres of estuaries and coastal rivers. The property loss due to erosion and must make Carolina Sea Grant guide, Shoreline abundance of bayfront vistas and recreational decisions regarding whether or not to Erosion in North Carolina Estuaries by opportunities is paralleled by the dynamic and stabilize waterfront property (Figure 1, next Stanley R. Riggs. changing nature of these regions, often creating page). These are complex decisions because • Basic elements of site evaluation are conflicts between the increasing demand for there are numerous options for shoreline presented, including parameters for shoreline properties and the ongoing erosion stabilization. evaluating specific sites. processes. Estuarine property owners and local • A range of stabilization options is Shoreline erosion is a natural process governments face difficult choices as they presented: wetlands planting options, stone involving prevailing wind, wave and current strive to select appropriate strategies to structures and vertical walls. In some cases, conditions. The actual erosion rate within an control erosion that are cost-effective and property owners may handle the task alone. area may vary within estuarine systems and environmentally sound. In others, professional services or guidance over time, depending upon individual site Managing Erosion on Estuarine are required. Some property owners may conditions and the frequency of storms or Shorelines is part of The Soundfront Series. choose to live with the conditions. other causes of erosion. This guidebook provides a basic understand- • An overview of the permit process North Carolina’s estuarine landscapes ing of the nature and causes of shoreline provides readers contact information for have changed considerably over centuries. erosion, and introduces a number of the North Carolina Division of Coastal Agricultural areas, residential subdivisions and management strategies. This publication is Management (DCM). Updated regulations commercial and industrial facilities have intended to provide general guidance, and are available online or at DCM offices in replaced once-forested shorelines. As a result, not to be considered a construction Raleigh and the coastal region. increased runoff containing sediment and other specifications manual. A landowner may • Additional resources will assist pollutants has entered the surface waters and undertake some approaches, while other landowners in making and implementing groundwater supplies. Natural marsh fringes options should be pursued with the erosion-control decisions. that onceIntroduction buffered and protected uplands have assistance of an experienced professional. Individual property owners, develop- eroded due to natural and man-made causes, In order to provide practical shoreline ers and local officials may have interest in resulting in higher rates of upland erosion and management options, this guide focuses on specific segments of estuarine shoreline. associated water quality concerns. several topics: This guide will put decisions regarding • Causes and effects of erosion are these specific segments into a larger discussed briefly in this guidebook to help perspective. Page 2 Page 3 Figure 1. M a n a g i n g E r o s i o n Chapter 2: Planning for Estuarine Shoreline Stabilization Options Estuarine property owners often have Table 1. Shoreline Management Goals compared to vertical walls. However, difficult decisions regarding specific sites with planting a marsh with no structural enhance- active shoreline erosion. Their options may be • Stabilize shorefront lands and structures ment is generally recommended only for influenced by permit and policy decisions against erosion. lower energy areas. In addition, two or more made by resource managers who must • Protect and/or enhance property values. approaches may be considered for a balance land-use options with the long-term • Provide for human safety. particular site, but evaluation of costs, access health of the estuarine environment. • Achieve cost-effective solutions. for equipment or availability of materials The first step in developing a shoreline • Protect water quality by reducing runoff may narrow the options. management strategy is to define goals that and preserving buffers. Shoreline management decisions are benefit the property owner and reduce • Preserve, enhance or restore natural based on a variety of factors, including negative impacts on the natural environment wetlands, sandy beaches and other priorities, goals, cost, site conditions and land (Figure 2, next page). Once appropriate goals intertidal habitats. use. Information sources include consultants are selected, the property owner should • Protect existing or create new uses such and contractors with experience in the determine the specific nature of the erosion as boating access or swimming. following areas: problem, evaluate the existing site condition, • Ensure compatibility with adjacent land • Coastal erosion and choose one or more options to success- uses. • Shoreline management options fully address the erosion problem and achieve • Natural resource protection the management goals. Table 1 identifies eight In some cases, one goal may be • Marine construction possible goals. Other site-specific goals may achieved at the expense of another. Priorities • Permit requirements depend upon the use, geography or access. may vary within different stretches of • Relative costs for various strategies shorelines or among neighboring properties. In choosing a consultant or contractor, Also, it is difficult to achieve all goals at the take time to visit completed projects and talk lowest cost. For example, the option of with the property owners to assess their level wetland plantings is environmentally of satisfaction. beneficial and may be relatively inexpensive Table 2 provides a spectrum of shoreline Table 2. Shoreline Management Options Land Management Vegetation Beach Fill or Nourishment Shoreline Hardening Sand Traps • Development setbacks • Planted native marsh • Add sand to an existing • Bulkheads • Groins • Live with erosion grasses, such as cordgrass natural beach • Revetments • Breakwaters • Managed buffer of mixed and black needlerush • Marsh sills shoreline vegetation in intertidal area Stabilization Options Page 4 Page 5 Figure 2. T h e S o u n d f r o n t S e r i e s shorelines. Give consideration to the need for, and possibility of, a cooperative project between
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