This grid represents the distribution of hydraulic head in the Spirit River hydrostratigraphic unit (HSU). It is a result of a geostatistical model which was constructed using publicly available pressure data from oil and gas well drillstem tests.
The hydraulic head distribution was mapped at a regional scale using many years of data, thus providing a good indication of regional groundwater flow within the unit rather than site-specific values.
The following statistics describe the accuracy of the geostatistical layer used to create the final grid.
Mean error = 0.6 m
Root mean square error = 40.2 m
Mean standardized error = 0.00661629
Root mean square standardized = 0.9802375
Average standard error = 39.4 m
The root mean square error of the final smoothed grid is 20 m
Selection criteria and the final data set used for interpolation of this grid are documented in the metadata for AGS Digital Data 2022-0022.
Step 1 (Modelling the surface): An empirical Bayesian kriging algorithm was used in the ArcMap Geostatistical Analyst extension to interpolate the hydraulic head values and create a grid of the head surface of the Spirit River HSU.
Method Report:
Output surface type: Prediction
Transformation: None
Neighbourhood type: Standard circular
Maximum neighbours: 8
Minimum neighbours: 8
Sector type: 4 sectors
Samples: 380
Cell size: 500 m
Step 2 (Grid Smoothing): The grid was smoothed using focal statistics which calculates for each input cell location a statistic of the values within a specified neighbourhood around it, in this case a 3-cell radius. Smoothing the surface used the average cell value.
Step 3 (Grid Alterations): The final grid was clipped based on the extent of the Spirit River HSU, and spatial distribution of data.