SIMULATION OF REACTIVE GEOCHEMICAL TRANSPORT PROCESSES IN CONTAMINATED AQUIFERS USING SURROGATE MODELS

Abstract

Transport of contaminant species undergoing chemical reactions in groundwater aquifers is a
complex physical and biochemical process. Simulating this transport process involves solving complex nonlinear
equations and requires huge computational time for a given aquifer study area. Development of optimal
remediation strategies in aquifers may require repeated solution of such complex numerical simulation models.
To overcome this computational limitation and improve the computational feasibility of large number of
repeated simulations, Genetic Programming based trained surrogate models are developed to approximately
simulate such complex transport processes. Transport process of acid mine drainage, a hazardous pollutant is
first simulated using a numerical simulated model: HYDROGEOCHEM 5.0 for a study area resembling a mine
site. Simulation model solution results for an illustrative contaminated aquifer site is then approximated by
training and testing a Genetic Programming (GP) based surrogate model. To decrease the total number of GP
formulations, the coordinates of observation locations are implemented as input data in the surrogate models.
Comparison of the surrogate models and numerical simulation results show that the surrogate models can
provide acceptable approximations of this complex transport process in contaminated groundwater aquifers.