Effect of Buffer Zones on Estuarine and Riparian Land Use in Eastern North Carolina

Southeastern Geographer Vol. XXIX, No. 2, November 1989, pp. 136-149 EFFECT OF BUFFER ZONES ON ESTUARINE AND RIPARIAN LAND USE IN EASTERN NORTH CAROLINA* Jonathan D. Phillips INTRODUCTION. Stormwater-borne (nonpoint source) pollution from urban and agricultural runoff is a critical water quality problem in the North Carolina Coastal Plain. Nutrient and sediment pollution of rivers and estuaries is largely attributed to farm runoff, while bacterial contamination of shellfish beds and recreational waters and accumulations of metals and toxics in coastal waters have been linked to urban, residential , and recreational development along North Carolina's estuarine shorelines. (J) A key management technique for dealing with these runoff-borne pollutants is the maintenance of vegetated riparian buffer zones. These buffers provide filters to cleanse contaminated runoff before it can enter surface waters, delay stormwater so that contaminants may decompose or settle out, and simply move development farther from the shore, which reduces pollutant delivery. In the case of agricultural nonpoint source (NPS) pollution, riparian buffers are generally in the form of bottomland forests along stream corridors. Where the concern is stormwater from urban and commercial shoreline development, the buffer is typically a vegetated (usually with grass) setback from the water line. Establishment and maintenance of an undeveloped vegetated area along stream banks and estuary shores have significant potential landuse implications. In the case of coastal shorelines, there are clear economic impacts because of strong development pressures, intense landuse competition, and the extremely high value of waterfront property. These variables are usually not important along inland stream corridors in Eastern North Carolina, but restrictions on rural and agricultural land use are even more controversial than in residential and commercial areas. (2) * Information provided by Lynn Phillips (Director, Carteret County Planning Department) was helpful in interpreting the land-use implications of the buffer model. Leo Zonn provided useful comments on an earlier draft. Dr. Phillips is Associate Professor ofGeography and Planning at East Carolina University in Greenville, NC 27858. Vol. XXIX, No. 2 137 The purpose of this paper is to determine the extent to which establishment of riparian buffer zones to control stormwater pollution would alter current land-use patterns in Eastern North Carolina. The Riparian Buffer Delineation Equation (RBDE) recently has been developed for delineating riparian water quality buffers, (3) but it is used here to address the implications ofbuffer establishment on riparian land use in the Coastal Plain region and specifically to evaluate the extent to which buffer establishment could restrict uses ofriparian land. This paper does not focus on the problem of delineating or evaluating riparian buffers, but instead emphasizes the land-use implications of establishing and maintaining vegetated buffers. Two situations within the North Carolina Coastal Plain are examined . First is the problem of estuarine shoreline buffers for Carteret County, a coastal county experiencing intense shoreline development and associated stormwater pollution problems. Second, the problem of agricultural NPS pollution and streamside buffers is addressed for a two-county area along the lower Tar River. STUDY AREAS. The North Carolina Coastal Plain is a broad, low-relief surface composed mainly of marine sediments deposited during higher Pleistocene stands of sea level, sometimes veneered with recent alluvium . There is a gradually decreasing elevation and increasing thickness of coastal and marine sediments overlying crystalline bedrock from the Fall Line (inland boundary with the Piedmont physiographic province ) to the Atlantic Ocean. The estuarine study area, Carteret County, lies on the coast, and most of the county's waters are tidal. The inland study area, Pitt and Edgecombe counties, flanks the lower Tar River from the Fall Line to the head of tidewater (Fig. 1). The climate of the North Carolina Coastal Plain is warm and humid, with long hot summers and short mild winters. Topography is flat to gently rolling. Major geomorphic surfaces include broad upland interfluves , river and sea level terraces, alluvial valleys and floodplains, and coastal wetland/estuary/barrier island complexes. (4) Due to the climate, soils are characterized by rapid decomposition of organic matter, relatively rapid chemical reactions and leaching of soluble bases, and translocation of less-soluble fine particles to the B-horizon. Upland soils are thus generally acidic, strongly leached, and low in natural fertility. Wetland...