The bedrock geologic units designate units of the same types of rock which composed the solid rock exposed at ground surface (as outcrop) or which underlies unconsolidated surficial sediments. This dataset represents a general description of the stratigraphy and geology, including geologic unit thickness, morphology, age and rank. It features a list of the geologic unit names and types of rock (lithology) in the hydrogeological unit, from a controlled vocabulary. While the preferred format to deliver this data is by using a shapefile and its linked attributes, this dataset can be delivered also by providing link to external data which should have at least the same properties or also by joining a georeferenced image of the map.

Level below which soil or rock is saturated with water, in the well and at the time the level has been measured, expressed in m above the sea level. Groundwater levels measured are interpolated / extrapolated to obtain groundwater level on every cell of the hydrogeological unit raster. Surfer and ArcGis are the software usually used to create groundwater level raster. The dataset designates a raster with a groundwater level, for each cell of the hydrogeological unit.

A hydrogeological unit is defined as any soil or rock unit or zone that by virtue of its hydraulic properties has a distinct influence on the storage or movement of groundwater. It is considered the main dataset from the GGP point of view. Hydrogeological units are ranked into five levels (from largest to smallest): 1) hydrogeological region, 2) hydrogeological context, 3) aquifer system, 4) hydrostratigraphic unit, and 5) aquifer. Here are formal definitions for these different types of hydrogeologic units. - Hydrogeological region Hydrogeological regions are areas in which the properties of sub-surface water, or groundwater, are broadly similar in geology, climate and topography. There are 9 such regions identified in Canada (ref?). - Hydrogeological context Hydrogeological contexts are units of reporting, conceptually narrower than regions, and are additionally delineated by physiographic and hydrogeological aspects. - Aquifer system ""A heterogeneous body of intercalated permeable and poorly permeable material that functions regionally as a water-yielding hydraulic unit; it comprises two or more permeable beds [aquifers] separated at least locally by aquitards [confining units] that impede groundwater movement but do not greatly affect the regional hydraulic continuity of the system"" (Poland et al., 1972). - Hydrostratigraphic unit (HSU) ""Body of sediment and/or rock characterized by ground water flow that can be demonstrated to be distinct under both unstressed (natural) and stressed (pumping) conditions, and is distinguishable from flow in other HSUs"" (Noyes et al.) - Aquifer ""A formation, group of formations, or part of a formation that contains sufficient saturated permeable material to yield significant quantities of water to wells and springs"" (Lohman et al, 1972, p. 21). The rank attribute is used to specify the scope of the described unit. The general principle behind this specification is to allow the same data structure to apply to various types of hydrogeological units, from the local aquifer to the almost continental hydrogeological region. The dataset includes properties such as identification, physiography, geology, aquifer description and properties, water balance, groundwater use and risk. It features numerical values or a general description when no values are available. The description can also be used to add context to the numerical values. For each property, metadata identifying the source of the original data, links to similar data in GIN, and description of the processes, algorithms or methodology used to obtain these datasets will be available to complement the data. This dataset is designed to capture and represent a set of synthesized information pertaining to hydrogeological units through maps and succinct table reports. Some attributes (or properties) of the dataset are irrelevant depending of the rank of the unit. In general, this dataset is organised to include multiple properties associated with aquifers and larger hydrogeologic units. These properties are grouped into categories, which include identification, physiography, geology, aquifer description, water balance, groundwater use and risk. The numerical values associated with each of the properties can be used to create thematic maps; hence, the importance of using standardized units of measurement and definitions for these properties. When numerical values are not available, a general description may be supplied instead. The description can also be used to add context to the numerical values. Because this dataset is the cornerstone of the national view on groundwater, supplemental contextual information (metadata) must be part of the data. Thus, for each property, metadata identifying the source of the original data, links to similar data in GIN, and a description of the processes, algorithms or methodology used to obtain these datasets will be available to complement the data.

Groundwater flow is the movement of water in an aquifer or hydrogeological unit. The dataset shows groundwater flow rate and direction in the hydrogeological unit. Groundwater flow is establish from piezometric surface map. The method used to create the dataset is described in the metadata associated with the dataset. The dataset represents a description of the flow, including rate in m/d, direction, date and source. Typically, the data provided will not be in the form of a shapefile with linked properties but in the form of an image that sketches the groundwater flow. The image could also represent a cross section of the hydrogeologic units showing the regional trends of the groundwater flow.

Hydraulic properties characterize a hydrogeological unit. The hydraulic properties considered for this dataset are the transmissivity, the hydraulic conductivity, the storage coefficient, the specific storage coefficient and the porosity. Hydraulic properties are estimated by performing aquifer tests (pumping tests, slug tests). The hydraulic tests and their duration are managed in this dataset. The methods used to create the dataset are described in the metadata associated with the dataset. The dataset exhibits a general description of hydraulic properties of the hydrogeological unit, including hydraulic test, total test duration, method and date. It includes numbers and/or ranges describing the aquifer tests results. Note that an alternate raster representation could be used in complement to the discrete point-based representation.

Surficial geologic units are unconsolidated materials overlying bedrock. The dataset represents a general description of the stratigraphy and geology, including geologic unit thickness, morphology, age and rank. It features a list of the geologic unit names and types of sediment in the hydrogeological unit. While the preferred format to deliver this data is by using a shapefile and its linked attributes, this dataset can be delivered also by providing link to external data which should have at least the same properties or also by joining a georeferenced image of the map.

A measure of the intrinsic susceptibility of an aquifer representing the tendency or likelihood for contaminants to reach a specified position in the groundwater system after introduction at some location above the uppermost aquifer. The method used to create the dataset is described in the metadata associated with the dataset. The dataset is a general assessment of the vulnerability of the hydrogeological unit considered as a whole. It features the local and regional qualifiers in a controlled vocabulary list referring to the extent where the vulnerability value is valid. Because the vulnerability is assessed using contextual indices linked to the regional hydrogeological settings, it is very unlikely to have an homogeneous range of data throughout the various hydrogeologic units across the country for this dataset. Hence, the vulnerability dataset will not qualify as an homogeneous dataset. A more generic reclassification using for examples three vulnerability classes could then be used to solve this problem. Each sub layers used to create the global vulnerability index can be provided along with the final vulnerability index map.

In the hydrogeological unit, quantity of water that replenishes groundwater beneath the water table, expressed in mm/yr. Recharge is usually calculated using hydrology balance, integrating information from precipitation, hydrology data, drainage, soil properties, evapotranspiration, etc. The result is a raster dataset in which each cell has a given value for the recharge of the aquifer. It can be calculate using HELP software, developed by the US EPA. The methods used to create the dataset are described in the metadata associated with the dataset. The dataset represent a raster in which each cell has a mean value describing the global annual recharge of the hydrogeological unit.

Groundwater samples have been collected in the hydrogeological unit, for various types of analysis. The dataset is not used to represent a particular phenomenon or observation but rather as a utility dataset to add context and reference to groundwater analysis. It represents a general description of the sample site and sample. Sampling methods vary according to the types of analysis.