Conceptual Model Approach
GMS is a powerful graphical tool for model creation. Models can be built using digital maps and elevation models for reference and source data. During the model building process, the graphical representation of the model allows quick review and presentation of your work.
One of GMS's greatest strengths is the conceptual model approach which allows users to build models conceptually independent of their numerical grid. This approach makes it possible to build a conceptual model using GIS feature objects (points, arcs, and polygons). The conceptual model defines the boundary conditions, sources/sinks, and material property zones for a model. The model data can then be automatically discretized to the model grid or mesh. The conceptual model approach makes it possible to deal with large, complex models in a simple and efficient manner.
The GIS Module now available in GMS has made creating conceptual models from GIS data even easier. With direct linkage to ArcGIS and almost any format of GIS data, you can access geometry and attributes faster than ever before. Whether the GIS data is created in GMS or imported from GIS files, the method of model building remains the same. The model is edited at the GIS object level. GMS automatically generates the mesh and assigns parameters and boundary conditions to each element of the model.
To illustrate the conceptual model approach, consider the site shown in the following figure. It represents information that might be available from a combination of sources including maps, photos, and GIS data. This information may include the location of hydrologic features as well as hydrologic properties of the site. However, this information is not yet organized into a form that is useful to a numerical model.
The first step in creating a conceptual model of this site is to create points, arcs and polygons that represent hydrologic features at the site. These points, arcs and polygons are assigned types that correspond to the feature they represent. Based on the attribute type, parameters such as head, concentration and conductance are assigned to these feature objects. The resulting coverage is shown in the following figure. Other coverages, defining such things as recharge zones, would also be defined.
The final step is to take the information that is stored in the conceptual model and construct a numerical model. GMS automates both the creation of the grid geometry as well as assigning boundary conditions and material parameters to the grid. Refine points can be used to specify areas where the grid should have a high density. By specifying polygons that represent the domain of the model, it is possible to automatically inactivate all the cells that lie outside that domain. Boundary conditions may be applied to the individual cells that are intersected by specified feature objects. In addition to determining which cells are assigned boundary conditions, GMS also calculates the appropriate values to assign to each stress period of a transient simulation. The resulting numerical model is illustrated in the following figure.
For more detailed information on the Conceptual modeling Approach in GMS visit the GMS wiki at: www.xmswiki.com/...Conceptual