Frequently Asked Questions - Near Real-Time Data

Q. What is meant by near real-time data?
A. Near real-time data is data that is available for viewing after a relatively short time span between the time of data sampling from a remote location and the viewing of that same data within the comfort of an office or laboratory. The remote location may be as far away as a distant mountain location or as close as a point on a river in the city where the viewing facilities are located. Alberta Environment personnel view the majority of near real-time data within as little as 1 hour from the time of sampling. Public viewing of the same data presented in graphical and table format on the Web/site is later and largely dependent on frequency of updates to the Web/site.

Alberta Environment's near real-time data gathering process takes advantange of recent advances in satellite, telephone and computer communication technology.

Q. Is the near real-time data checked?
A. The near real-time hydrometeorological data is quality assessed and quality controlled (QA/QC'd) daily in the morning to ensure accuracy and completeness. During flood events hydrometeorological data are "QA/QC'd" more frequently.

Q. Why has today's flow value changed from yesterday's value?
A. Water levels and flow values are adjusted as required to compensate for either natural river environment changes (vertical or horizontal channel shifts, beaver dams, aquatic vegetation, etc.) or instrumentation errors (staff gauge movement, instrumentation drift, power fluctuations etc.).

Q. When are the near real-time data and associated figures updated on the Internet?
A. Update frequencies are generally as follows:
  • River data figures are updated four times daily
  • Precipitation data figures are updated four times daily
  • Lake and Reservoir level figures are updated four times daily
  • Snow data figures are updated twice daily
  • All data tables are updated on an hourly basis however due to transmission times or failed connections the data will be older than the time of update.

Q. How are stream levels/stages acquired?
A. Stream levels/stages are acquired at a specific location for a stream or river by referencing the water level to a known vertical point (elevation). That vertical point may be some structural element on a structure on/by the river, a spike in a tree, a Geological Survey of Canada (GSC) survey benchmark, etc. The reference point may be an assumed elevation or a known geodetic elevation (reference to sea-level), however what is important is that all subsequent water levels be referenced to that initial elevation in order to have a continuous record of water levels. For ease in determining that distance between subsequent water levels and that initial elevation, a gauge (can be as simple as a long ruler) is placed in a strategic location so that: water levels contact the gauge over a wide vertical range of water levels, and, those levels can be easily determined either by manual observance or automation. A point on the gauge is referenced to the initial elevation to establish the elevational relationship between the gauge and that initial elevation. For a more detailed description of gauges and recording methods we refer you to Water Survey of Canada's gauging stations section of their Hydrometric Technician Career Development Program.

Q. How do you get flows(discharges) from stream levels?
A. By measuring flow (a costly and time consuming task) for a range of water stages, a stage-discharge relationship is established for a specific location on a stream or river. When the stage-discharge relationship is fully established a corresponding flow/discharge can be derived from a given water level (stage). Water levels can be acquired quickly and remotely therefore providing near real-time flows. Water Survey Canada has an excellent Web/site that describes in detail the relationship between stage and discharge See also the next FAQ for flows under ice conditions.

Q. Why are flows not updated during the winter months?
A. All real-time hydrometric flows are derived by measuring the water level/stage, and applying that level to a relationship which relates stage to flow. Since ice cover introduces a number of uncertainties, such as additional friction losses and back water effects, the stage versus flow relationship, and, consequently the flow estimate is not reliable under ice conditions. However some flows can be estimated using deterministic and/or statistical methods such as the Athabasca River below Fort McMurray. The Athabasca River below Fort McMurray is the only winter flow estimate available online as of November 2002.

Q. Is there any real-time Water Quality and Private Reservoir data available?
A. Near real-time Water Quality data (water temperature, dissolved oxygen, water pH, etc.), and Private Reservoir hydrometeorological data (reservoir water level, outflows, air temperature, etc.) can be viewed under the category "Miscellaneous and Water Quality Data". Willow Creek at Oxly Ranch is a good example of water quality data.

Q. Why are there two categories of meteorological data, i.e. "precipitation" and "meteorological"?
A. The "precipitation" category contains the three and six hour accumulated totals which in many cases is graphed. The "meteorological" data (table format only) contains not only hourly accumulated precipitation but other meteorological parameters such as air temperature, humidity, wind direction, wind speed, etc.

Q. Where can I get historical data since the data only goes back two or three days?
A. There are two sources of historical data related to the near-real-time data:
  • For Alberta Environment historical hydrometeorological data contact Data Management of the Environmental Monitoring and Evaluation Branch.

  • For national historical meteorlogical data visit Environment Canada's self-serve Web/site.

Q. Is near real-time hydrological data for Alberta available elsewhere on the Internet?
A. Yes, Water Survey of Canada provides near real-time and historical water levels from 1700 stations across Canada including Alberta.

Q. How do I interpret a streamflow graph?
A. Here's how to interpret a stream flow graph.....

Q. How do I interpret a precipitation graph?
A. Here's how to interpret a precipitation graph...

Q. How do I interpret a snow pillow graph?
A. Here's how to interpret a snow pillow graph...