This grid represents the hydraulic head distribution in the Peace River / Viking / Bow Island 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. Formation pressure data from drillstem test and production fluids from oil and gas wells
The head surface was mapped at a regional scale using many years of data, thus providing a good indication of regional water groundwater flow within the unit rather than site-specific values.
The following statistics describes the accuracy of the final grid before smoothing:
Root mean square error: 13.9 m
Mean error: 0.24
Mean standardized error: 0.012
Root mean square standardized: 1.09
Average standard error: 15.94
The root mean square error of the final smoothed grid is 11.8 m.
See AGS DIG 2020-0002 (data points) for details on the horizontal accuracy of the input hydraulic head point data, which is affected by the locational accuracy of the wells.
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 2-cell radius, smoothing the surface using the average cell value.
Selection criteria and the final dataset used for interpolation of this grid are documented in the metadata for AER/AGS DIG 2020-0002.
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 Peace River / Viking / Bow Island HSU.
Method Report:
Method: Kriging
Type: Simple
Transformation: Normal Score
Output type: Prediction
Trend type: None
Variogram: Semivariogram
Number of lags: 12
Lag size: 10079
Nugget: 0.0122
Measurement error percentage: 100
Model type: Stable
Range: 80637.9
Anisotropy: No
Partial sill: No
Total points: 1465
Coordinate System: NAD_1983_10TM_AEP_Forest
Datum: D_North_American_1983
Data declustering: Cell
Cell size : 12622
Searching neighborhood: Smooth
Smoothing factor: 0.2
Root mean square error: 1.09 m
Mean: 0.24
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 2-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 Peace River / Viking / Bow Island HSU, and spatial distribution of data.