Flood of the Century
What DOES James Avenue Datum Mean?
During the flood, we heard daily references to James Avenue Datum. But what exactly does it mean?
James Avenue Datum is a reference or scale used to measure elevations within the city of Winnipeg. It was developed to measure elevations relative to the normal winter river ice level where James Avenue meets the Red River. This normal winter ice level was established as 727.57' above sea level and is defined as 0' James Avenue Datum. The normal summer water level at James Avenue is usually regulated by the St. Andrews Lock & Dam at approximately 7.0' James Avenue, or 734.5' above sea level.
The location of the Red River at James Avenue was chosen to measure water levels as it is downstream of Assiniboine River flows. A downtown City facility, James Avenue High Pressure Pumping Station, is located on the riverbank.
How Does it Work?
Within the Pumping Station, vital pieces of equipment - chart recorder, control box, electronic level transmitter - give the City a water level reading from the James Avenue location. An electronic level transmitter - a measuring tape - drops into a culvert that goes out to the Red River. It measures water pressure as it comes up or down, sends a signal to the control box, which transmits every 15 minutes via the telephone line to the McPhillips Control Centre. In earlier years, prior to electronic readings, the station was manned 24 hours a day and was used to collect information for the operation of St. Andrews Lock & Dam.
Water pressure is measured through this culvert that goes into the Red River.
The City of Winnipeg also monitors and records the river levels at Bishop Grandin Boulevard and Chief Peguis Trail. These levels are monitored ultrasonically, measuring the distance between the probe and the water level by bouncing a signal off the water. It works a lot like radar. The information recorded is then fed back to the McPhillips Control Centre. During the flood, the City monitored water levels at all these points.
Why Is It So Important?
River monitoring sites provide:
- important information to operations staff in the event of ice jams
- a better understanding of the behavior of the river system
- a better idea of site-specific elevations for sewer gate operations and sandbagging/diking requirements
Additional monitoring sites along the Assiniboine River are planned in the near future. The data from these sites will provide an even more complete picture of the river system's behaviour.
Recent Flood History
Source: Diking Commissioner’s Reports As reference, the normal summer river level is 6.5 feet James while the River Walkway level is 8.5 feet James. |
Historic Flood Levels
* Before construction of the Floodway |
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