A Load of Bull
One of the more interesting facts we probably all learned and remember from school Geography was the Oxbow lake. Yet most of us probably haven't actually seen one.
Here is a location that (depending on the height of the grass and reeds) you should be able to see an example in real life.
Logging tasks
| Task # |
Logging Tasks |
| 1 |
At the GZ - look at the location of the river on either side of the road and determine if an oxbow lake is likely to form here or not in the future? What processes or features do you think withh encourage or hinder the formation of an oxbow lake here? |
| 2 |
Describe an oxbow lake you can see [a photo wpould be useful too] |
| 3 |
Looking at the slope of the river from the steep upper slopes in the Berg near Sani to the sea (you can also look to the north of this site to the small plateau as see some small tributaries entering the main river) - could you explain the difference in the energy of the water and where it causes erosion or deposition. |
| 4 |
Looking south east (the Reichenau mission station is very close - and well worth a visit) you can see a change in the land shape- describe the change of the land and if you would imagine any oxbow lakes to form in the river immeadiately below the Reichenau mission. |
An oxbow lake starts out as a curve, or meander, in a river. A lake forms as the river finds a different, shorter, course. The meander becomes an oxbow lake along the side of the river.
Oxbow lakes usually form in flat, low-lying plains close to where the river empties into another body of water. On these plains, rivers often have wide meanders.
Meanders that form oxbow lakes have two sets of curves: one curving away from the straight path of the river and one curving back. The corners of the curves closest to each other are called concave banks. The concave banks erode over time. The force of the rivers flowing water wears away the land on the meanders concave banks.
The banks opposite the concave banks are called convex banks. The opposite of erosion happens here. Silt and sediment build up on convex banks. This build-up is called deposition.
Erosion and deposition eventually cause a new channel to be cut through the small piece of land at the narrow end of the meander. The river makes a shortcut. Oxbow lakes are the remains of the bend in the river.
Oxbow lakes are stillwater lakes. This means that water does not flow into or out of them. There is no stream or spring feeding the lake, and it doesnt have a natural outlet. Oxbow lakes often become swamps or bogs, and they often dry up as their water evaporates.
Oxbow lakes can be rich wildlife habitats. Along the Amazon River in South America, oxbow lakes are common and their still waters provide a unique habitat for plants and wildlife. Giant river otters frequently live in the Amazons oxbow lakes, and feed on about 5 kilograms (11 pounds) of fish per day.
People often create oxbow lakes. The Mississippi River is shorter now than it was in the 19th century, for instance, because engineers have cut off hundreds of meanders. This created hundreds of oxbow lakes. These lakes eventually dried up to create acres of land for farming, housing, and industry.
An oxbow lake gets its name from the U-shaped collar placed around an oxs neck to which a plow is attached. It can also be called a horseshoe lake, a loop lake, or a cutoff lake.
An interesting fact that the Australian BILLABONG is also an Oxbow lake.
References:
https://www.nationalgeographic.org/encyclopedia/oxbow-lake/