Abstract
The increasing environmental concern over hazardous emissions from landfills, landfarms, settling ponds, agricultural fields, surface mines, and surface impoundments has renewed interest in improving concentration estimates downwind from area sources. Simplistic and numerically efficient methods (for estimating area source impacts) are the virtual point source approach (Turner, 1970) as used in the models LONGZ (Bjorklund and Bowers, 1979) and VALLEY (Butt, 1977), and the finite line source approach as used in ISCST (Bowers et al., 1979). The virtual point source and finite line segment algorithms are most appropriate for estimating concentrations at downwind distances significantly larger than the side width of the area source (Hwang, 1986 and Weber, 1982). However, these constructs fail for concentration estimates within or near the area source. Thistle and Londergan (1989) showed that these algorithms behaved in a manner inconsistent with mathematical and physical principles. They demonstrated that models that use numerical techniques to approximate the Gaussian point source dispersion function over the area source are more realistic although computationally intensive. One of the models that they found to be mathematically and physically consistent was PAL (Petersen and Rumsey, 1987).
Published Version
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