Before any type of geospatial modeling or related decision analysis framework may be applied, the site must be partitioned into a grid or block system.
This step is available when one of the following interviews is selected: Interpolate my data, Draw a variance map, Draw a probability map, Draw an area of concern map, Calculate cost versus cleanup, Draw a LISA map, Draw a contoured risk map, Draw a contoured eco dose map, and sometimes Develop a sample design.
Select Set grid specs from the Steps Window. The following information is displayed in the Parameters Window.
Grids may be developed based on number of blocks or size. To develop a grid based on number of blocks, click in the button next to Number. Then, specify the number of blocks in each direction. To develop a grid based on size of blocks, click in the button next to Size. Then, specify the size of blocks for each direction.
By default SADA calculates a global grid that extends to the minimum and maximum value taken over all data in the east and north coordinates. This allows the user to spatially sum risks over analytes easily and consistently. SADA then calculates the sub grid that encompasses all associated data points for the current analyte of interest.
To view the grid, press the Show Grid button.
Under the grid view, the user may then refine the spatial boundaries with the use of polygons to include or exclude blocks from analysis.
If the grid is three-dimensional, the user needs to define the vertical position in each box for interpolating the data (middle or top). See set vertical layers to define this position. To view subsequent levels of the grid, use the layers box.
Once the site has been partitioned, a geospatial models may be applied. See Overview of Geospatial Modeling.