LINEAR REFERENCING AND GIS USED TO DISPLAY MULTIPLE SHORELINE CHARACTERISTICS BY REDUCING SPATIAL COMPLEXITY

Geographic Information Systems (GIS) has enhanced the capabilities of earthscientists to convey diverse information visually. Traditional geologic maps are constrained by the two-dimensionality of paper, and by the finite ability of humans to distinguish among shades of color. A traditional geologic map conveys spatial (x, y, z) information using a two dimensional display and contours, point data by symbology, boundaries by line type and weight, and a limited number of geologic interpretations by color and by overlay patterns. Hard-copy maps effectively communicate spatial variability of a single attribute or aggregate information such as bedrock geology. However, an earthscientist may wish to effectively and simultaneously present disaggregated data or multi-dimensional information.

Using GIS and linear referencing, multiple characteristics of Great Salt Lake’s shorezone on Antelope Island were displayed concurrently. Characteristics included point data such as surveyed elevations, line data such as distribution of trash, and areal data such as rock type derived from geologic maps. Values for 25 attributes along the island’s 65 km shoreline were displayed on a single 36 inch x 44 inch sheet of paper, a display of over a million data values.

By defining the shorezone as a line, location in 2-dimensional geographic space was collapsed into 1-dimension, a referenced distance. Linear referencing can achieve reduction of spatial complexity associated with linear geologic features such as faults, and for boundaries such as coastal zones. With simultaneous display of multi-dimensional information about a feature, an earthscientist can visually compare spatial relationships among multiple attributes. Interpretations can be published with supporting data that normally would not appear on a hard-copy map.