Processes

• What are the factors affecting the discharge of a river?

  Factors include precipitation, evaporation, and human activities.
• What controls the point of maximum velocity in a river channel?

  The shape of the cross section of the channel.
• How does channel shape affect river flow?

  Friction increases at the edge of the channel, resulting in slower flow.
• What is the difference between symmetrical and asymmetrical channels?

  • Symmetrical channels have equal sides, leading to uniform flow.
  • Asymmetrical channels have unequal sides, causing distorted flow patterns.
• What is the wetted perimeter in a river?

  The total length of the bed and banks in contact with the water in the channel.
• What is the hydraulic radius?

  The ratio of the cross-sectional area to the wetted perimeter.
• How do you calculate the hydraulic radius (HR)?

  $HR =$$\frac{Cross-sectional \ area}{Wetted \ perimeter}$
• Which channel is more efficient: Hydrangea or Eskdam?

  Eskdam is more efficient with a hydraulic radius of $0.25m$.
• How does the roughness of a riverbed affect flow velocity?

  Smoother surfaces have lower frictional drag, increasing flow velocity.
• What are the key points about the upper course of a river?

  • Increased resistance due to boulders and inclusions.
  • Increased friction reduces overall velocity.
  • Turbulence increases due to uneven roughness.
• What are the key points about the lower course of a river?

  • Little resistance from smooth bed and banks.
  • Reduced friction increases overall velocity.
• How does channel slope affect river velocity?

  Steeper gradients generally lead to higher velocities due to gravity.
• What must a river overcome to transport and erode material?

  • Friction with the bed and banks.
  • Internal friction of the water.
• What happens to a river's velocity as it flows through a desert?

  The velocity increases as it flows through a desert.
• What is the process of erosion in a river channel?

  Erosion changes the shape of the river channel.
• What are the four processes of erosion in a river?

  1. Solution (Corrosion)
  2. Abrasion
  3. Hydraulic Action
  4. Attrition/Corrosion
• What is solution or corrosion in river erosion?

  It involves chemicals in water dissolving rocks, especially in carbonate rocks.
• How does abrasion occur in a river?

  It occurs when bedload collides with other materials and the riverbed.
• What is hydraulic action in river erosion?

  It is the force of water entering cracks in the banks, causing collapse over time.
• What is attrition in river erosion?

  It is the process where the river load rubs against the bed and banks, wearing them down.
• What are the methods of transportation in a river?

  1. Solution
  2. Suspension
  3. Bedload (Saltation and Traction)
• How does solution transport material in a river?

  It involves water dissolving minerals and transporting them in solution.
• What is suspension in river transportation?

  It is when fine particles are carried by turbulence in the water.
• What is bedload in river transportation?

  It consists of larger particles that cannot be picked up by the current.
• What is saltation in bedload transportation?

  It is when pebbles and sand are temporarily lifted and bounced along the bed.
• What is traction in bedload transportation?

  It is when large cobbles and boulders roll or slide along the bed.
• What happens during deposition in a river?

  • Occurs when river velocity decreases.
  • Silt is laid down starting with the largest particles.
  • Deposition occurs in various conditions such as low precipitation and entering the sea.
• What is the relationship between capacity and competence in a river?

  Capacity is the maximum quantity of material a river can transport, while competence is the total load actually transported.
• What does Hjulstrom's curve illustrate?

  It shows the relationship between particle size and the energy required for erosion and transportation.
• What is required to transport larger particles in a river?

  More energy is needed to erode or transport larger particles.
• Why do silt particles require high velocities to move?

  Silt particles are cohesive and tend to stick together, creating a smooth surface.
• How does the velocity of a river affect sediment transport?

  Higher velocities increase the quantity and size of particles that can be transported.
• What happens to dissolved load in a river?

  Dissolved load is carried out to sea and maintains the saltiness of the oceans.
• What is the effect of decreased gradient on a river's ability to transport sediment?

  As the gradient decreases, the bedload and ability to transport sediment also decrease.
• What is the significance of the heaviest material being deposited first?

  It increases the wetted perimeter and affects the river's flow characteristics.
• What happens to gravel, sand, and silt during deposition?

  They are carried further downstream to be deposited in the channel and over floodplains.
• Where are the finest particles typically deposited?

  They are deposited where rivers meet the sea, forming deltas or estuaries.
• What happens to the dissolved load during deposition?

  The dissolved load is not deposited but carried out to sea.
• What is the relationship between velocity, transportation, and deposition?

  Increased velocity allows a river to transport more material before deposition occurs.
• What is the effect of a river reaching flood levels on its energy?

  The amount of energy available for transportation increases rapidly.