Database Manual

Oak Ridges Moraine Groundwater Program

Section 2.3.9

Section 2.3.9 HYDAT And Spotflow Data


Source HYDAT information is available from Environment Canada as a Microsoft Access database; from this, daily flow rates can be extracted from the DLY_FLOWS table. However, this table is found to be in ‘spreadsheet’ (i.e. column-centric) format. All information for a particular month is found on a single row with days-of-the-month identified as ‘FLOW1’ (for the first day of the month), ‘FLOW2’ (for the second day of the month), etc… (to a ‘maximum’ day identifier of ‘FLOW31’ for the applicable months), as shown.

Figure HYDAT source data Figure HYDAT source data

Here, the STATION_NUMBER identified is ‘02GA045’; this maps to both a location and interval identifier in the database as well as, being a ‘surface water station’, a surface water identifier.

The latter contains both HYDAT stations (indicated as ‘Active’ or ‘Inactive’) as well as locations of spotflow measurements (indicated as ‘Local Station’); this information is available in the field ‘SWStationComment’.

The actual temporal data (i.e. the values in FLOW1 through FLOW31) are stored in the D_INTERVAL_TEMPORAL_5 table, as shown.

Figure HYDAT data stored in D_INTERVAL_TEMPORAL_5 Figure HYDAT data stored in D_INTERVAL_TEMPORAL_5

The original-source values are found in the fields

Note that the RD_NAME_OUOM field should be populated with ‘Stream Flow - Daily Discharge (Average)’ (not shown here), specifying the ‘type’ of measurement being stored. The fields that would subsequently be populated with the appropriate ‘system’ codes (usually by SiteFX) include

Baseflow Data

As of Dated Version 20170922, baseflow estimations are no longer stored in the database. These are calculated on-the-fly using applications found on the ORMGP website.

Spotflow Data

These locations are stored/found in the ORMGP database much as the ‘Hydat Stations’, above. Under SW_COMMENT (in D_SURFACEWATER) however, ‘Spotflow’ locations are indicated with a ‘Local Station’ tag or a value of ‘3’ for SW_SUBTYPE_CODE.

Usually, this information consists of single readings at a particular location. These values are also stored in D_INTERVAL_TEMPORAL_5 with slight differences to that of the ‘Hydat’ data, above.

Figure Spotflow data stored in D_INTERVAL_TEMPORAL_5Figure Spotflow data stored in D_INTERVAL_TEMPORAL_5

Here, the following apply