Assessment of the Buffer-Induced Setback Effects on Riparian Scenic Quality by Digital Tools

Abstract

Under a typical riparian landscape structure where a vegetated buffer is sandwiched between a greenway trail and the river bank or lake shore, a trail user's perceptions about riparian scenic quality are influenced by, among other factors, buffer-induced setback effects. As a trail is set back to leave enough space for the vegetated linear area, both the subject and the composition of a trail user's viewshed can change significantly. This may in turn affect his or her perceptions of the lakescape or riverscape. For greenway trail planners, the buffer-induced setback effects become most relevant when they have the option of allocating trails behind either a legislature-regulated buffer with constant width or a scientifically recommended buffer of variable width. In North Carolina's Piedmont region, the discrepancy in width between constant and variable buffers may range from 10 to 200 m, large enough to cause significant visual variances. In this paper a method to investigate these setback effects is presented. Based on Shafer's landscape-photography approach, a technique called BISEA (buffer-induced setback effect assessment) is designed to inquire and represent two pieces of information about the setback effects. These are: (1) the subject and composition changes in prospective trail users' viewsheds caused by buffer-width variations; and (2) the impacts of these changes on riparian scenic quality as perceived by trail users. Implementation of the method is facilitated by a computer-based support system that comprise tools for landscape photography (a digital camera), survey [a global positioning system (GPS) receiver], image processing (a digital image-processing program), database management and visualization (a GIS), and scenic quality assessment (a spreadsheet program).

A Shape-Based Buffering Method

“…Many buffers in the real world are not simple geometric shapes, but rather are derived from environmental interactions or expert input based on knowledge of the study area's topography, soil, land use, property ownership, and other factors. For example, GIS-based riparian buffer analyses were conducted on North Carolina watersheds to delineate variable-distance buffers through the injection into the model of environmental or expert information such as soil, slope, vegetation, and scenic quality (Xiang, 1993;1998;Xiang and Stratton, 1996). Buffering was applied to the delineation of biosphere reserves in New Jersey Pinelands based on the theory of island biogeography, according to which, ecosystem management can be operated by identifying core areas of high ecological value, and surrounding them with protective buffers (Walker and Solecki, 1999).…”

The Characteristics of Riparian Buffer Studies

“…Tufford et al (1998) employed GIS to visualize the relationships among streams, land use and pollution within riparian buffers. Xiang (1998) studied the buffer-induced setback effects on riparian aesthetics with GPS and GIS technology. During this period of time, an emerging area of study was watershed modeling, and exemplified by the development and application of such models as the Groundwater Loading Effects of Agricultural Management Systems (GLEAMS).…”