Risk Assessment (Stochastic) Modeling
One of the most exciting features in GMS is a suite of tools for performing stochastic simulations with MODFLOW and accompanying transport models.
GMS has a Risk Analysis Wizard to help determine risk based on the results from stochastic modeling simulations. Two types of analysis are currently supported: probabilistic threshold analysis and probabilistic capture zone delineation. This wizard allows you to quantify the risk of a contaminant exceeding critical levels in groundwater or the risk of a capture zone including key areas at a site. Such analysis helps determine appropriate action to be taken in design or remediation.
Two approaches are supported for setting up stochastic simulations: parameter randomization approach and indicator simulation. The parameter randomization generates the different realizations using either a Random Sampling (Monte Carlo), Latin Hypercube Sampling or Gaussian Fileds. The indicator simulation approach randomizes the spatial distribution of the parameter zones using the T-PROGS software. The T-PROGS software is used to perform transition probability geostatistics on borehole data. The output of the T-PROGS software is a set of N material sets on a 3D grid. Each of the material sets is conditioned to the borehole data and the materials proportions and transitions between the boreholes follows the trends observed in the borehole data. These material sets can be used for stochastic simulations with MODFLOW.
Stochastic inverse modeling can also be performed wherein parameter estimation is performed for each run in a stochastic simulation to find the optimal values based on observation data. Also a statistical analysis can be computed on a Stochastic MODFLOW or MT3D solution. Data sets for the mean, min, max, and standard deviation can be created and visualized.
