Rain presently forecast for this week is expected to cause a significant increase in flows and water levels, potentially to 1:4 year frequency (flow that has a 25% probability of occurrence in any year).
There is still some snow in the Rideau River watershed which will be much reduced today with the arrival of temperatures above 10 degrees. This will increase flows slowly through the day. Twenty millimetres of rain now forecast for Tuesday will cause further increases. Fifty millimetres of rain on Thursday and Friday can be expected to bring a peak on Saturday possibly in the range of 450 to 500 cubic metres per second (cms) on the Rideau River at the monitoring station at Carleton University. The historical 30-year mean flow at the Carleton gauge is 320 cms.
Such flows in the system will cause flooding of access roads at Hilly Lane and other low-lying communities in the Long Reach of the Rideau River between Kemptville and Kars beginning Tuesday with the first bout of rain this week. By Thursday night, waterfront streets in Ottawa South like Belmont Avenue and Rideau River Drive along with Windsor Park can be expected to have water on the streets and on the pathway in the park. Flows can be expected to decline through the weekend.
With the increasing flows and rain, everyone needs to be cautious around all waterbodies. Children need to be warned of the dangers of flowing, cold water.
Conservation Authority staff will continue to monitor conditions and issue further statements as conditions warrant.
RVCA Watershed Conditions Statements:
- Water Safety – High flows, unstable banks, melting ice or other factors that could be dangerous for recreational users such as anglers, canoeists, hikers, children, pets, etc. Flooding is not expected.
- Flood Outlook – Early notice of the potential for flooding based on weather forecasts, calling for heavy rain, snow melt, high winds or other conditions that could lead to high runoff, cause ice jams and/or lakeshore flooding or erosion.
- Flood Watch – Flooding is possible in specific watercourses or municipalities. Municipalities, emergency services and individuals in flood prone areas should prepare.
- Flood Warning – Flooding is imminent or already occurring in area watercourses.