This grid represents the hydraulic head distribution in the Dunvegan hydrostratigraphic unit (HSU). It is a result of a geostatistical model which was constructed using publicly available data from the following sources:
1. Alberta Environment and Parks (AEP) Alberta Water Well Information Database (AWWID)
2. Pressure data from drillstem tests from oil and gas wells
The hydraulic head surface was mapped at a regional scale using many years of data, thus providing a general indication of regional groundwater flow within the unit rather than site-specific values.
See AER/AGS DIG 2020-0031 (data points) for details on the vertical accuracy of the input data, which is affected by the locational accuracy of the wells.
The following statistics describes the accuracy of the final grid before smoothing:
Root mean squared error : 18.8 m
Mean error : 1.05
Mean standardized error: 0.02
Root mean square standardized error: 1.19
Average standard error: 19.18
Selection criteria for data from AWWID and oil and gas well DSTs, as well as the final data set used for interpolation of this grid are documented in the metadata for AER/AGS DIG 2020-0031.
Step 1 (Modelling the surface): A simple 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 Dunvegan HSU.
Method Report:
Method: Kriging
Type: Simple
Transformation: Normal Score
Output type: Prediction
Trend type: None
Variogram: Semivariogram
Number of lags: 12
Lag size: 0.2693
Nugget: 0.016
Measurement error percentage: 100
Model type: Stable
Range: 2.154
Anisotropy: No
Partial sill: NO
Total points: 102
Coordinate System:GCS_North_American_1983
Datum: D_North_American_1983
Neighbourhood type: Standard
Root mean square error: 1.19
Mean: 1.05
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 4-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 Dunvegan HSU and spatial distribution of data.