Frequently Asked Questions - GWSDAT Data Analysis/Plotting functions - Functions associated with spatial plot window

The “GWSDAT options” dialogue box, which appears when “GWSDAT analysis” is selected, allows the user to select the time interval between spatiotemporal model output plots. The pre-defined user options are “None”, “Monthly” or “Quarterly”: the model sets the start and end dates for the intervals by working backwards from the most recent sampling date. Concentration contour plots are generated by exporting data from the spatiotemporal model at the end of each specified time interval.

The “GWSDAT options” dialogue box also controls the handling of groundwater elevation data. If no aggregation (i.e. “None”) is selected then the software will attempt to generate a groundwater contour plan for every date in the input dataset. In practice, however, groundwater elevation surveys are often spread over a number of days and so this approach is likely to generate incomplete contour plots. If “monthly” or “quarterly” aggregation selected the software collates daily groundwater elevation data into monthly or quarterly blocks, thereby increasing the size of the dataset available for piezometric contouring.

Solute concentration contours are generated using a spatiotemporal smoother algorithm, which fits a model to the solute concentration distribution through space (XY well coordinates) and time. This does not involve any temporal collation of the input concentration dataset. For further details refer to GWSDAT software manual.

Piezometric contours are generated using an adaptive kriging algorithm. The degree of flexibility allowed by the kriging algorithm is a function of the number of groundwater elevation data points in the selected model output interval, which improves the contour quality for smaller datasets. 

Solute concentration contour plots have default logarithmic scales of 0 to >50,000 ng/L, 0 to >5000 ug/L or 0 to > 500 mg/L, dependent on the units selected. The concentration scale is fixed so that contour plots for successive time slices are directly comparable. The user can, however, select to “scale colours to data” to produce a colour key scaled to the concentration range for each model output interval.