In geography, a confluence is the meeting of two or more
bodies of water. It usually refers to the point where two streams
flow together, merging into a single stream. It can be where a
tributary joins a larger river, called the main stem, or where two
streams meet to become a river with a new name
The Thompson River
The Thompson River is the largest tributary of the Fraser
River drainage system, it was named by Simon Fraser, in honour of
his friend, David Thompson.
At Kamloops, the Thompson River flows 15 km from the
confluence of the North and South Thompson River branches before
reaching Kamloops Lake. From there the River flows in a meandering
course westwards through a broad valley area before it meets the
Fraser River in Lytton.
The two major tributaries of the Thompson River, the North
and South Thompson Rivers, are very different rivers! From spring
to early fall, the North Thompson River is a cold and an opaque
grey colour, while the South Thompson is warmer and a clear
blue-green colour.
Tracing the North and South Thompson Rivers back to their
headwaters reveals that both rivers drain the rugged Columbia
Mountains and its many glaciers. Streams that flow from these
glaciers are very muddy because they carry glacial silt. The North
and South Thompson River branches travel a great distance and have
access to many large lakes on their way to Kamloops.
However, a large part of the North Thompson River does not
flow through the lakes contained in Wells Gray Park, and therefore
the mud and silt eroded from mountain glaciers are carried all the
way to Kamloops.
The South Thompson River flows directly through the Shuswap
Lake system. As the water slows and moves through the large lake
the glacial silt settles to the lake floor. The only way for mud to
get into the South Thompson River is through tributaries that enter
the river downstream from Shuswap Lake.
Muddy water is a concern for the residents of Kamloops as the
City draws its domestic water from the South Thompson River. For
many years muddy water (turbidity levels) created problems for
water treatment. The turbidity problem was solved when the Water
Treatment Plant was built in 2005.
To log this earthcache you need to email the following
requirements to the cache owner:
- In what years did the four major historic floods occur on
the Thompson River?
- Calculate the flow rate in "Meters Per Second" near the
confluence of the river, and post your value with your log for
others to compare.
This may be done by measuring a distance along the rivers
bank, floating an object from your starting point to the ending
point, and recording the time it takes the object to float the
distance. Once the "Distance" and "Time" are determined, calculate
the "Meters Per Second".
-
In your own words summarize why the water in the North and
South branches are different in colour and temperature.
- The posting of a photo is optional.