Understanding
Streamflow is a measure of volume over time and reported in cubic metres per second (cms). Velocity is a measure of distance over time and is reported in metres per
second (m/s). There are two main methods used in the RVCA baseflow survey for
measuring streamflow: the velocityarea method and the volumetime method. Both
methods are commonly used in Ontario.
The velocityarea method entails dividing the cross section of the stream in a number of smaller sections and measuring the velocity of the water in each section using a current metre. The flow is calculated in each section by multiplying the velocity by the area of the section. The total flow across the river is calculated by summing the flows calculated at each section.
To measure streamflow using the volumetime method one times how long it takes to collect a known volume of water. This method is ideal for small flows passing through culverts at a road crossing. If the culvert is raised slightly from the ground a bucket or container of a known volume is placed under the stream falling from the culvert. The flow is calculated by dividing the volume of water collected by the time it takes for the stream to fill the container.
The data set provided here includes the final calculated flow at the baseflow measurement site and the measurement method used. The data set is divided by the subwatersheds of the RVCA: Jock River, Tay River, Rideau Lakes, Lower Rideau River and Kemptville Creek. The baseflow measurement sites in each subwatershed are indicated. Currently there are baseflow sites in only the Jock River and Tay River watersheds.
