S h o r e l i n e E r o s i o n Chapter 1: The Estuarine Shoreline Erosion Dilemma North Carolina’s estuaries The world’s glaciers are still melting Change is a constant within dynamic represent a geologically young and dynamic today. Sea level continues to rise. And the coastal zones and guarantees no perma- portion of the coastal system. Estuarine ocean, slowly but relentlessly, floods the nency to any structure or feature along coastal systems occur where ocean waters coastal lands of North Carolina. This the shorelines. For those who live and mix with river waters. As the last great results in the ongoing upward and work along the water’s edge, an ex- Pleistocene ice sheet began to melt in landward migration of the shoreline — tremely high level of property loss results response to global climate warming over a process better known as shoreline from storm-induced flooding and 10,000 years ago, the present coastline erosion. People who build near the shoreline erosion. The burgeoning began to develop. estuarine shoreline become partners in population and exploding development As the glaciers melted and receded, the this natural process. demand for shoreline stabilization to meltwaters raised the ocean level. This rising The fact that sea level is rising protect property. However, such efforts sea level caused the coastal system to worldwide means that erosion is ubiqui- can result in negative impacts upon the migrate across the continental shelf, flooding tous to all of North Carolina’s thousands coast and a cumulative toll on the health over the land and up the topographically of miles of shoreline. The only differ- of the entire estuarine system. low-river valleys to form our present ences are the rates of erosion, which are Native Americans inhabited coastal estuarine system. dependent upon specific shoreline North Carolina prior to 10,000 years ago. After 10,000 years, 425 feet of sea- variables and varying storm conditions. However, there are few records remain- level rise, and a lateral migration of 15 to 60 Locally, a shoreline may appear stable or ing of their occupancy. Even the record of miles westward, the North Carolina coast actually accrete sediments, but such a the first European settlement on Roanoke began to develop its now familiar look of situation is usually ephemeral. Island in 1585 has been obliterated by estuaries and barrier islands. shoreline recession. Consequently, great monuments from our present coastal civilization will probably not survive into antiquity. Today, the processes of change continue to take their toll as every nor’easter and hurricane place their mark upon the shifting sands of time. This is our coastal heritage. Erosion Dilemma Next page: This high sediment bank is actively eroding. Page 2 Page 3 T h e S o u n d f r o n t S e r i e s In 1975 Vince Bellis and colleagues island consisted of 40 acres occupied by of estuarine shoreline change from a used the demise of Batt’s Island in houses and orchards (Powell, 1968). geologist’s perspective. A more inclusive Albemarle Sound to demonstrate the Bellis et al. (1975) estimated that the document on North Carolina’s Estuarine process of estuarine shoreline recession in island was about 10 acres in size on an Erosion by Stanley R. Riggs will be response to rising sea level. This island, 1849 U.S. Coast and Geodetic Survey available from the N.C. Division of which occurred about 0.75 miles offshore map. By the early 1970s, a lone cypress Coastal Management and North Carolina of Drummond Point at the entrance to skeleton marked the total demise of the Sea Grant for those who wish to read Yeopim River, first appeared on the 1657 island (Figure 1.1B) and by the early about these concepts in more detail. Comberford map (Cumming, 1938) as 1990s a red buoy marker reflected the Using this guide, public property Hariots Island. The island subsequently presence of shallow shoals (Figure 1.1D). managers and private property owners became the home of Captain Nathaniel The loss of Batt’s Island is symbolic should be able to characterize specific Batts, the first Virginian to settle in the of the ongoing loss of land in eastern North sections of estuarine shoreline and, in Albemarle region and the governor of Carolina (Table 1.1). Over 500 acres are Chapter 4, determine the erosion potential. “Roan-oak.” The island is referred to as lost per year, and over 40 square miles of This guide and three others — which are Batts Grave on the 1733 Moseley and land has been lost between 1975 and 2000. available from North Carolina Sea Grant — 1770 Collet maps (Cumming, 1966) This guide provides key concepts in can provide the tools to understand and live (Figures 1.1A and 1.1C). In 1749 the understanding the various types and rates with our dynamic estuarine shorelines. Table 1.1. Potential Land Loss in Northeastern N.C. Estimates of potential land loss in the NE coastal region of North Carolina over the past 25 years in response to ongoing sea-level rise and estuarine shoreline recession based upon analysis and integration of data from the USDA (1975) and Riggs et al. (1978) studies SHORELINE AVG RATES MILES & % ANNUAL LAND TOTAL ESTIMATED TYPE OF EROSION MAPPED LOSS ON 1,593 LAND LOSS FOR MILES MAPPED NE N.C. 1975–2000 • Sediment Bank Low 2.6 ft/yr 471 mi (30%) 149 acres/yr 11.6 mi2 High 1.9 ft/yr 111 mi (7%) 25 acres/yr 2.0 mi2 Bluff 2.1 ft/yr 21 mi (1%) 5 acres/yr 0.4 mi2 • Organic Bank Swamp Forest 2.1 ft/yr 110 mi (7%) 28 acres/yr 2.2 mi2 Marsh 3.1 ft/yr 880 mi (55%) 330 acres/yr 25.8 mi2 TOTAL LAND LOSS 537 ACRES/YR 42.0 MI2 * This assumes that Riggs et al. (1978) mapped 50% of the estuarine shorelines in NE North Carolina. These numbers are on the conservative side since most of the shorelines in Pamlico Sound were not mapped or included in the data base, and Pamlico Sound has the highest rates of shoreline erosion. Page 4 S h o r e l i n e E r o s i o n FIGURE 1.1. Map and photo series showing the demise of Batts Island at the mouth of the Yeopim River in Albemarle Sound. Panel A. The Moseley map of 1733 (Cumming, 1966) refers to the island as Batts Grave. Panel B. Photograph in the early 1970s showing a lone cypress skeleton marking the final demise of the island. Panel C. Portion of the US National Oceanographic and Atmospheric Administration A (NOAA) Nautical Chart 12205, Page E, 1976, showing the former location of Batts Grave. Some areas represent less than 6-foot water depth. The arrow indicates the former location of Batts Grave, which is the seaward extension of Drummond Point. As sea level rises, water floods onto the land and wave energy causes the shoreline to recede by erosion. C Panel D. Photograph in the early 1990s showing the bouy that marks the shallow shoal remnants of Batts Grave. B D Page 5.