Streamflow gauging stations

The map shows the location and the number of years of recorded data for the Water Survey of Canada streamflow gauging stations and the Quebec Department of Natural Resources stations. Almost 9 per cent of all the world's river water which flows to the oceans has its source within Canada's boundaries. Because water is an extremely valuable natural resource, it is vital to monitor Canada's rivers for a continuous assessment of streamflow distribution and its variability. The stations depicted on the map represent points where water level measurements are made and converted to streamflow discharge (in cubic feet per second or cubic metres per second). Water levels, called "stage", are translated to discharge by means of a "stage-discharge" curve or rating curve, which is established by measuring discharges for various stages as they occur throughout the year. The individual discharge measurements are made by determining the velocity profile or mean velocity for incremental portions of the total river cross-section. Velocities can be determined by a number of methods but the cup-type meter is the one generally used in Canada. Table 1 indicates the distribution of gauging stations. The historical growth in the number of gauging stations operated in Canada is illustrated in Figure 1. Approximately 30 per cent of the active stations measuring streamflow are in operation only during the open-water season or irrigation period. In addition to the formal network depicted on the map, provincial and private agencies operate a number of stations taking miscellaneous measurements, periodic gauge readings, or relatively short-term records.