Project Based Learning
Why are rivers so important? - The Features of a River
Hello Year 3, last week, we introduced ourselves to our new project based learning topic of rivers. We took a look at many different activities that helped us build our knowledge of rivers.
This week we are going to be thinking about the features of a river.
A river consists of 3 sections.
The Upper Course
The Middle Course and
The Lower Course
This week we are going to explore these different sections of a river and explore the different features which might be present within each section.
Monday - WALT: explore landforms of the upper course of a river by creating a sketch
The upper course of a river begins at its source.
As the river moves through the upper course, it cuts downwards.
The gradient here is steep and the river channel is narrow.
Vertical erosion in this highland part of the river helps to create steep-sided V-shaped valleys, interlocking spurs, rapids, waterfalls and gorges.
As the river erodes the landscape in the upper course, it winds and bends to avoid areas of hard rock. This creates interlocking spurs, which look a bit like the interlocking parts of a zip.
When a river runs over alternating layers of hard and soft rock, rapids and waterfalls may form.
For todays lesson, I would like you to use the diagram below in order to create your own sketch of the upper course of a river. Once you have finished this, I would like you to colour your sketch in.
Tuesday - WALT: explore waterfalls by creating a fact file of famous waterfalls
During todays lesson we are going to be looking at a key feature of the Upper Course of a River: Waterfalls.
Waterfalls are formed where water rushes down steep hillsides in upland areas. The height and number of waterfalls along a stream or river depend upon the type of rocks that are being eroded by the water. This typically occurs in areas where alternating bands of rock, made up of soft and hard rock, form the bedrock. Some types of rocks (shale, for example) wear away more easily than others (such as sandstone or limestone).
Waterfalls form when water falls onto soft rock after flowing over hard rock. Falling water and rock particles erode the soft rock below, forming a plunge pool. Processes of erosion, such as hydraulic action, abrasion and corraision further erode the plunge pool and the back wall of the waterfall, undercutting the hard rock above. eventually, the hard rock will no longer be supported and it will collapse. The waterfall continues to retreat leaving behind a steep-sided gorge.
The diagram below shows the formation of a waterfall.
For todays session, I would like you to research two different waterfalls that can be found across the world.
Can you find one Waterfall that is in the United Kingdom?
Can you then find another waterfall that is somewhere else in the world?
Wednesday - WALT: explore the features of the middle course of a river by creating a sketch
In the middle course the river has more energy and a high volume of water. The gradient here is gentle and lateral (sideways) erosion has widened the river channel. The river channel has also deepened. A larger river channel means there is less friction, so the water flows faster.
During todays lesson, I would like you to create another sketch. This time I would like you to use the diagram below to sketch the middle course of a river.
Once you have completed your sketch, can you colour the different aspects of the middle course in?
Thursday - WALT: explore the formation of meanders and ox-bow lakes by creating a story board
During the middle course of a river, meander are often formed.
In the middle course the river has more energy and a high volume of water. The gradient here is gentle and lateral (sideways) erosion has widened the river channel. The river channel has also deepened. A larger river channel means there is less friction, so the water flows faster:
- As the river erodes laterally, to the right side then the left side, it forms large bends, and then horseshoe-like loops called meanders.
- The formation of meanders is due to both deposition and erosion and meanders gradually migrate downstream.
- The force of the water erodes and undercuts the river bank on the outside of the bend where water flow has most energy due to decreased friction.
- On the inside of the bend, where the river flow is slower, material is deposited, as there is more friction.
- Over time the horseshoe become tighter, until the ends become very close together. As the river breaks through, eg during a flood when the river has a higher discharge and more energy, and the ends join, the loop is cut-off from the main channel. The cut-off loop is called an oxbow lake.
Upstream a large bend becomes a horseshoe and is eventually cut-off to become an oxbow lake. Downstream the river is eroding its outer bank and depositing on its inner bank to create a new meander.
During todays lesson, I would like you to use both the information above and the diagram below in order to create a storyboard explaining the formation of both meanders and ox-bow lakes.
Friday - WALT: explore the landforms of the lower course of the river by creating a sketch
In the lower course, the river has a high volume and a large discharge. The river channel is now deep and wide and the landscape around it is flat. However, as a river reaches the end of its journey, energy levels are low and deposition takes place.
The river now has a wide floodplain. A floodplain is the area around a river that is covered in times of flood. A floodplain is a very fertile area due to the rich alluvium deposited by floodwaters. This makes floodplains a good place for agriculture. A build up of alluvium on the banks of a river can create levees, which raise the river bank.
Deltas are found at the mouth of large rivers - for example, the Mississippi. A delta is formed when the river deposits its material faster than the sea can remove it. There are three main types of delta, named after the shape they create.
Arcuate or fan-shaped:
The land around the river mouth arches out into the sea and the river splits many times on the way to the sea, creating a fan effect.
The land around the mouth of the river juts out arrow-like into the sea.
The river splits on the way to the sea, each part of the river juts out into the sea, rather like a bird's foot.
During todays lesson, I would like you to complete your trio of sketches by using the diagrams below in order to sketch the landforms of the lower course of the river.
Once you have completed your sketch, can you colour it in.