The St. Lawrence River is embracing Montreal, and it looks like it was always there but will it stay ?
This river suffers from Fluctuations in water levels and flows, whether natural or the result of human activities, and this changes are a major concern among stakeholders involved in managing the water and its uses and for scientists who are working to protect the fluvial ecosystem. For more information visit Environment Canada
So what are those NATURAL Fluctuations in Rivers or Lakes?
The Natural Fluctuations is the water levels of rivers, streams and channels are closely linked to short-term (days or weeks) meteorological changes, as well as to long term (decades or centuries) and seasonal climatic variations. The aquatic and semiaquatic plants, along with all the other living creatures that live in the wetlands surrounding these rivers have to adapt to all the fluctuations great and small. When significant variations occour, either increases or decreases, the balance in the river ecosystem is unavoidably disrupted, affecting the diversity and aboundance of flura and fauna which are found here.
This is an Earthcache so we will only focus on the Natural reasons, but even with the hydropower dam, water levels on the lake and river are determined largely by natural factors such as precipitation, evaporation and runoff.
Precipitation in the form of rain, snow and condensation is the source of all waters reaching the Great Lakes and then Rivers. Over-lake precipitation represents a large and immediate supply of water to the Great Lakes because about one third of the Great Lakes basin area is Lake Surface. The land area contributing runoff to the Great Lakes, in a band from about 10 to 150 km wide around the lake shores, is drained by a system of rivers and intermittent streams. The amount of precipitation is fairly constant throughout the year, but winter precipitation stored as snowpack is a major contributor to spring runoff to the lakes.
Evaporation from the land and water surfaces depends on solar radiation, on temperature differences between the air mass and the water, and on humidity and wind. Evaporation is greatest in the fall and early winter when the air above is cold and dry and the rivers are relatively warm. Conversely, the evaporation is least in the spring and early summer when the air above is warm and moist and the rivers are cold. Condensation to the rivers surface may result instead of evaporation.
Groundwater is believed to be a minor component in adding or removing water from the lakes or rivers.
Ice retardation in the winter, when the flows in the outlet rivers of the Great Lakes are often impeded by ice formation or ice jams, and aquatic growth during the summer also have an effect on outlet flows and hence lake levels.
Tides, which are the periodic rise and fall of the water resulting from the gravitational interactions of the sun, moon, and earth.
So know that you know a little more about the subject and you have the sign next to you (at ground zero to help)
Here is what you need to do to log it:
- What type of river will be effected more from the changes one with a steep or shallow river band? and according to the sign what is the type of river band next to you
- Knowing Montreal and its climate in general what is the major influence for the river fluctuations ?hint : divide your answer to winter and summer (you can look at the graph in the link for help environmental Canada)
- Update: If the sign is not there you dont and cant do this one. Just to prove you were at ground zero, on the sign there are names of 4 agencies/organizations (bottom left corner, blue background) name 2.
- I would love it if you attach a picture from GZ (it is not mandatory)