River processes & landforms
Follow a river all the way from the mountains where it is born to the sea where it ends. In this lesson we map a river's drainage basin — its source, tributaries, confluence, mouth, watershed and catchment — then trace its long profile through the upper, middle and lower course. We meet the four ways a river erodes (hydraulic action, corrasion, corrosion and attrition) and the landforms they carve — waterfalls, gorges, rapids, potholes and meanders. We watch a river transport its load by traction, saltation, suspension and solution, and see where and why it deposits again, building floodplains, levees, deltas and Namibia's own oshanas. We finish by weighing the value of wetlands and how people are changing them.
By the end you should be able to (NSSCO Geography 1.3):
- Identify and describe the main features of a drainage basin with reference to the river channel, watershed and catchment area
- Describe the characteristics of a river valley in the upper, middle and lower course (the long profile)
- Describe the processes by which a river erodes its channel: hydraulic action, corrosion, corrasion and attrition
- Name and describe landforms of river erosion: waterfalls, rapids, meanders, potholes and gorges
- Name and explain the river transport processes: traction, saltation, suspension and solution
- Give the reasons why and where deposition takes place, with reference to the volume and velocity of flow, the nature of the load and the bed-rock
- Name and describe landforms of river deposition: deltas, levees, marshes, floodplains and inland deltas/oshanas
- Discuss the advantages and disadvantages of wetland areas such as floodplains and deltas, and the impact of humans on them
Mr Thomas and Mike talk through the whole topic — with the figure and working drawn live.