The Avon River
Originally named the "Little Thames River", the Avon River was named after the River Avon in England. It starts northeast of the city of Stratford (the headwaters), and flows southwest, joining the Thames River just north of the Town of St Marys (the confluence). The Avon flows into the Thames River, into Lake St. Clair, and eventually, into Lake Erie.
Length: 37 km
Discharge: 2.2 m³/s
Basin area: 1,678 km²
Watersheds
A watershed is an area of land that is drained by a river and its tributaries into a particular body of water such as a pond, lake or ocean. Think about your local creek, river or stream. Where does it start? What types of landscapes does it pass through and where does it end up? All of the area covered is a watershed.
A watershed is made up of a unique mixture of habitats that influence one another. These habitats include forests, wildlife, creeks, rivers and lakes, farms and even cities or towns. Watersheds come in all sizes – large and small.
For some educational facts on Watershed Divides, feel free to visit the Traditional Cache: GC3PTG9 - "Perth's Watershed Divide".
Floodplains
A floodplain is a low-lying plain on both sides of a river that has repeatedly overflowed its banks and flooded the surrounding areas. When the floods subside, alluvium is deposited on the floodplain. The larger materials, being heavier, are deposited at the river banks while the finer materials are carried and deposited further away from the river. The larger materials at the river banks build up into embankments called levees.
Erosion
One of the main reasons watersheds should matter is that the threat of erosion exists. Water flowing to a stream picks up dirt along the way. If the water picks up enough soil over time, the land along that stream will become unstable and eventually erode away. For wildlife that live in the area, it means a loss of their habitat. If you live along a river bank, this could mean losing a piece of your backyard.
Erosion is a continual process. While many people associate erosion with negative things, it is an important part of the geologic processes which make the Earth what it is. As soil and rock are slowly worn down, they cycle through the Earth's crust and the general environment, causing a constantly shifting and varied surface.
One of the most powerful causes of erosion is water. Rain and runoff contribute to erosion, as do glaciers, snow, and ice. Ice can be particularly insidious, because it will literally rip rock and soil apart as it expands and contracts.
Deforestation can also cause erosion, since it strips the protective surface plants and trees from the soil. The soil is no longer held in by roots and plant matter, so it slides away in rainy periods.
There are many signs that erosion has occurred or is occurring. Such signs may include, but are not limited to:
- Exposed Tree Roots: The force of the river flow washes away loose soil and rocks from
trees along the riverbank, exposing their roots.
- Cracks in the soil in a riverbank: Likewise, with the force of moving water, the
river cuts its own channel in the ground.
- Clumps of grass in the river: Eventually pieces of the shoreline break off into the
river.
- The top part of the riverbank overhangs: Over time, the lower part of the bank has
worn enough that the top portion appears to hang over the river.
- Brown or coloured water: The load of sediment the water carries is high enough that
the water appears murky.
- Collapsed riverbank: Eventually, the erosion has worn enough of the under portion of
the bank, that it falls into the river.
To date, 6,000 native trees and shrubs have been planted on 25 different farms in the Upper Avon River watershed. These trees help improve the environment by providing shade for the streams, reducing wind and water erosion, filtering and taking up nutrients, providing habitat for birds, and producing oxygen.
Forest cover in 2012 was 10.7 %. While that's a low level of tree cover, it is not unusual for an agricultural zone. There are 268 woodlots (most of them small) in the watershed.
The Report Card
The forest cover and river system along the Avon River has remained at a steady "D"-rating since 2000. The most recent grade, given at the time of this cache listing (5 March 2013), was, yet again, a D-rating. The provincial government would like to see this increased to a "B"-rating.
The Cache
The coordinates listed will start you at a group of 3 signs. However, there are another two signs further down the trail which will educate you more on what can be found in the Avon River (a number of "Species at Risk" are still able to survive here), and what is being done to help the Avon River.
From the information listed, the related website, and information found at the Earthcache location, answer the following questions:
a) What is the water flow travel time from Stratford to London? To Lake St Clair?
b) What is an indicator of good water quality?
c) From looking up and down the river at this location, would you say there has been
recent flooding? How can you tell?
d) In observing the river and the banks, what evidences (if any) can you find of erosion?
e) In your opinion, what do you feel needs to happen in order to raise the current
D-rating to the sought after B-rating?