Rivers GCSE WJEC

Rivers GCSE WJEC

1. Erosional river processes

   • Abrasion
     • As the river moves material it comes into contact with the wetted perimeter and wears it away
   • Attrition
     • As material moves by the river carry it - it hits other material and it gradually becomes rounder and smaller.
   • Solution
     • Acids in the river water dissolves soluble parts/elements of the river banks.
   • Hydrochloric Action
     • The sheer force and pressure of the river water moves material and dislodges it from the wetted perimeter.

2. Depositional Landforms

   • Slip off slopes
     • The inside bend of a meander.
   • Meanders
     • Outside bend: river cliff Inside bend: slip off slope. The river has less energy on the inside of the bend and starts to deposit material.
   • Ox bow lakes
     • Outside of meander is thalweg, inside is a slip off slope. - Increased erosion of meander neck - River flows in meander and straight through new channel (very straight) - drying up ox bow lake [water, lots of vegetation will become land]. - Will eventually start to meander again, rivers are not naturally straight.
   • Deltas
     • Need low energy environment and river material not wasted away
       • Can happen at sea/ocean, lake or other rivers

3. Transportation Techniques

   • Traction
     • Rolling of large materials along the river bottom
       • Needs lots of energy
   • Saltation
     • Sand sized particles hop along river bottom
   • Suspention
     • Silt and clay particles are carried suspended in the water.
   • Solution
     • Some minerals are dissolved in the river.

4. Erosional Landforms

   • Waterfalls
     • Need hard rock and soft rock under a river.
       • Waterfalls are formed when the soft rock erodes fastest.
         • Soft rock eroding more creates plunge pool and overhang forming a waterfall.
           • Overhang collapses into plunge pool eventually over time creating a gorge.
   • V shaped valleys
     • Water always runs to the lowest point and collects.
       • This forms a channel
         • Over time it erodes downwards cheating a V shape
           • Does not have enough energy to erode all the slopes so it moves around them
   • Interlocking spurs
     • *see V shaped valleys*

5. Tourism at Niagara Falls

6. YORK floods

   • 2000
   • 2012