GIS Based Chemical Fate Modeling: Principles and Applications

Chapter 9

Metamodeling and Source–Receptor Relationship Modeling in GIS

9.1 Introduction

When flows are controlled by gradients of a potential surface, such as surface water flows following gravity or groundwater flow following a stable water table with advection dominating over dispersion, two-dimensional trajectories are well defined. Under such circumstances, it is possible to apply the algorithms of hydrologic modeling in GIS to assess the fate and transport of contaminants. However, in other cases such as atmospheric or ocean transport, trajectories cannot be identified from the gradients of a potential surface. In such cases, the study of air or water currents and the associated advective and dispersive transport of contaminants requires complex two- or three-dimensional models of air or ocean circulation, which solve together the equations of flow and the ADRE. Models of this kind are computation intensive: they require a massive amount of input data and their development involves advanced skills in numerical analysis and programming. Once one such model is set up for a few chemicals, it can be run for other chemicals by changing only a limited number of input data: the distribution of emissions in space and time, and the physicochemical properties of a substance. However, each run requires relatively long computer time. At the same time, when looking at the predicted patterns of different contaminants, these can often be interpreted in the light of a few fundamental parameters ...