Geography: River Landscapes

Geography: River Landscapes

1. Path of a River

   • Upper Course
     • Steep
     • Narrow, shallow channel
   • Middle Course
     • Sloping valley sides
     • Wider, deeper channel
   • Lower Course
     • Very wide
     • Almost flat valley

2. Vertical Erosion

   • Deepens river valley and channel, making it V-shaped. In the upper course. High turbulence causes the rough particles to be scraped along the river, causing downwards erosion.

3. Lateral Erosion

   • Widens river valley and channel during the formation of meanders. Middle & lower course.

4. Processes of Erosion

   • 1
     • Hydraulic Action
       • Force of the water breaks rock particles away from the river channel.
   • 2
     • Abrasion
       • Eroded rocks, picked up by the river, scrape against the channel, wearing it away.
   • 3
     • Attrition
       • The eroded rocks smash into each other and break into smaller pieces. The further material travels, the more eroded it gets.
   • 4
     • Solution
       • River water dissolves some types of rock - E.G. Chalk and limestone

5. Transportation

   • Solution
     • Soluble materials dissolve and are carried along.
   • Suspension
     • Small particles are carried along by water.
   • Saltation
     • Pebble-sized particles are bounced along the river bed by the force of the water.
   • Traction
     • Large particles are pushed along the river bed by the force of the water.

6. Hard & Soft Engineering

   • Hard
     • Man-made structures built to control flow of rivers and reduce flooding.
     • Embankments - Raised walls built along the river banks.
       • + River can hold more water so it will flood less frequently, protecting buildings.
       • - A risk of severe flooding if the water rises above the level or if they break. - Quite expensive
     • Channel Straightening - River's course is straightened
       • + Water moves out of the area more quickly
       • - Flooding may happen downstream instead, as water is carried there faster and more erosion.
   • Soft
     • Flood Warnings
       • + Impact of flooding is reduced + People can evacuate
       • - People may not hear/access the warnings.
     • Schemes set up to reduce the effects of flooding
     • Planting Trees - Increases interception of rainwater and increases the lag time.
       • + Discharge and flood risks are reduced + Vegetation reduces soil erosion
       • - Less land is available for farming

7. Rivers Flood due to Physical and Human Factors

   • Heavy Rainfall
   • Prolonged Rainfall - Long Period of Rain
   • Relief - Change in the Height of the Land
   • Geology