An analytical model of contaminant transport from diffuse sources in saturated porous media

Abstract

An analytical two‐dimensional model of solute transport along a vertical cross section of an aquifer is described. The model extends analytical methods to two‐dimensional dispersive solute transport in a two‐dimensional flow field which until now has been the exclusive province of numerical models. This avoids the very significant problems of numerical instability and numerical dispersion facing the application of numerical transport models at a regional scale. Furthermore, the model is simple and very fast. A novel feature is the segregation of longitudinal and transverse transport components. The model is intended for preliminary evaluation of groundwater quality on a regional scale in areas subject to diffuse sources of contamination. It gives vertical resolution of contaminant concentrations through the aquifer thickness. Results compare favorably with finite element model results for a case involving a strip source of contaminants. It has been useful in predicting the impact of diffuse source nitrate contamination on groundwater quality in the Lower South East of South Australia.

Applications of Numerical Methods to Simulate the Movement of Contaminants in Groundwater

“…A new formula that is simpler than the former was presented recently by Hsieh (48). More analytical solutions can be found in Li (49), Bear (2) and Sun (8) (58), Chen (59,60), Lowell (61), and Dillon (62) (14) where Sy = specific yield (dimensionless); m = saturated thickness of the aquifer (L); W2 (L/T) and M2 (M/ L2 T) = sink or source; i,j = 1,2. …”

Regional monitoring of temporal changes in groundwater quality

“…Hallberg and Keeney (1993) showed that trends in groundwater quality can also be detected using concentration -depth information, because depth and groundwater age are interrelated under natural flow conditions. This phenomenon is most pronounced in groundwater recharge areas (Raats, 1978;Raats, 1981;Dillon, 1989;Broers, 2002;Broers, 2004). Environmental tracers, such as tritium, are useful for age dating of the groundwater.…”

Limiting analytical solutions for complex saturated and unsaturated transport problems

“…These methods are based on the assumption that it is possible to average velocity over the whole seepage domain (Freeze et al, 1979, p. 395) or along flow streamlines (Dillon, 1989). In doing so, initial and boundary conditions undergo similar changes or are chosen arbitrarily to permit analytical solutions.…”