Technical documentation: Hydrometric archive

This is the technical documentation for the Historical Hydrometric Data. The documentation provides a general overview of the dataset, a description of how the dataset was created, potential applications and any limitations of the dataset. For a general overview of climate information concepts, explore Climate information basics.

Overview

Historical hydrometric data are standardized water resource data and information. They are collected, interpreted and disseminated by the Water Survey of Canada (WSC) in partnership with the provinces, territories and other agencies through the National Hydrometric Program.

These data sets include daily mean, monthly mean, annual maximum and minimum daily mean and instantaneous peak water level and discharge information for over 2700 active and 5080 discontinued hydrometric monitoring stations across Canada.

Table 1. Main characteristics
Variables and units	Water Level (m) Discharge (m3/s)
Spatial resolution and geographical coverage	Point locations across Canada
Time period	Time period varies per station, per variable with data availability ranging between 1850 and 2017
Temporal resolution	Daily, monthly, and annual

Variables and formats

Historical hydrometric data provide the daily, monthly, and annual statistical values for two variables:

Water level: the elevation of the water surface in the stream at the hydrometric station above a reference point. Units are meters (m).
Discharge: the amount of water that is transported through a given cross-sectional area in the stream. Units are cubic meter per second (m3/s).

Daily data of water level and discharge

The daily data is the mean of unit values on a specific day. Daily water level data is available at 3483 stations. Daily discharge data is available at 6348 stations. The time periods of the data vary by stations, with the oldest water level data available from 1850 and the oldest discharge data available from 1860 at some stations to the most recent update in 2017. The data will continue to be updated every quarter.

Monthly data of water level and discharge

The monthly data is the mean value of the daily data when a month is a full month without missing daily values. The data will continue to be updated every quarter.

Annual maximum and minimum daily mean of water level and discharge

The annual daily statistics are the maximum and minimum daily data in a specific year. The data will continue to be updated every quarter.

Annual instantaneous peak water level and discharge

The annual instantaneous statistics are the maximum and minimum instantaneous value in a specific year. The data will continue to be updated every quarter.

Methods

Discharge is not measured directly. At each station, water levels are recorded continuously in digital form using a water level sensor connected to an automated electronic recorder, or data logger. The continuous water level data are then used to determine continuous discharge using a stage-discharge model.

To develop the model, a WSC hydrometric technologist visits the station several times a year to take direct measurements of discharge and water level. The technologist takes these direct measurements of discharge by deploying specialty instruments, from a bridge, by wading in a stream, by boat, or using a cableway strung across a river.

Once the relationship between water level and discharge has been established, through the development of stage-discharge curves, discharge values are derived continuously from the recorded and transmitted water level data.

In the office, the WSC technologists review and finalize the data under a rigorous quality management process. The data are stored in the national database and disseminated to users via the web site.

Station list

A list of hydrometric stations in a province or territory is available on the Canadian Centre for Climate Services’ Climate Data Extraction tool.

Application

The principal use of the hydrometric data includes water resources management and research, climate change research, environmental impact studies, and aquatic ecosystem research etc.

Users are urged to assess whether the datasets are suitable for their application. Users interested in complete disclaimer should refer to the Disclaimer for Hydrometric Information.

Limitations

The data are provided AS-IS. Continuous data review may result in revisions of the dataset. For most updated data, refer to the WSC Historical Hydrometric Data Online.