Digital Data 2022-0032

Author(s) Date 2022-12-05

The Alberta Geological Survey (AGS) and University of Calgary conducted a statistical analysis of 15 different groundwater quality parameters from available groundwater chemistry samples. The groundwater quality parameters are allocated to geological formations and summarized into township quadrants (i.e., quarter township) using the Alberta Township Survey (ATS) system grid.

Available groundwater chemistry and water well data were compiled from several sources, including the Alberta Environment and Parks (now Environment and Protected Areas) Alberta Water Well Information (AWWID) and Baseline Water Well Test (BWWT) databases, the Groundwater Observation Well Network (GOWN), Alberta Health routine and trace analyses database, and the Alberta Agriculture, Forestry, and Rural Economic Development (now Agriculture and Irrigation) groundwater sample database.

Available groundwater chemical analyses are allocated stratigraphically based on reported sample depth using the most recent version of the AGS Geological Framework of Alberta (GFAv3). Twelve geological units are represented in this feature layer: 1) sediment above bedrock, 2) Paskapoo and Porcupine Hills formations, 3) Scollard and Willow Creek formations, 4) Horseshoe Canyon Formation, 5) Wapiti and Brazeau formations, 6) Bearpaw Formation, 7) undifferentiated Belly River Group, 8) Dinosaur Park Formation, 9) Oldman Formation, 10) Foremost Formation, 11) Milk River and lower Lea Park formations, and 12) Doe Creek and Dunvegan formations. A selection of 15 groundwater quality parameters was summarized including: Ca, Mg, Na, K, NO3, SO4, Cl, HCO3, CO3, F, Fe, Mn, total dissolved solids (TDS), alkalinity, and hardness.

The geochemical statistical analysis summarizes the minimum, maximum and median concentration values (mg/L) of selected groundwater quality parameters within each quarter township and for each geological formation. The geochemical statistical summary also includes the 1st quartile (Q1), 3rd quartile (Q3) and interquartile range (IQR) for each groundwater quality parameter by quarter township. A measurement of variation (coefficient of variation) in parameter concentration around the median value in each quarter township is assessed using quartile data (Q1, Q3, and IQR) and, when combined with an evaluation of sample size, provides an indication of how well represented the median value is within the quarter township (representativity classification). A representativity classification of low, medium, or high is assigned to each select groundwater quality parameter for each quarter township and may be displayed as an additional layer, offering a visual of how well represented the median value is within the quarter township.

Place Keywords

Thistle, S., Humez, P., Pooley, K.E. and Liggett, J.E. (2022): Statistical summary and distribution of groundwater quality parameters by quarter township from selected Alberta geological units (GIS data, polygon features); Alberta Energy Regulator / Alberta Geological Survey, AER/AGS Digital Data 2022-0032.