option A - freshwater

• What does discharge refer to in the context of rivers?

  Discharge refers to the volume of water passing a certain point per unit of time.
• How is discharge usually expressed?

  Discharge is usually expressed in cubic metres per second (cumecs).
• According to the Bradshaw model, how does discharge change downstream?

  Discharge normally increases downstream.
• What happens to water velocity and discharge as you move downstream according to the Bradshaw model?

  Water velocity and discharge increase downstream.

  
• What happens to channel bed roughness and load particle size as you move downstream?

  Channel bed roughness and load particle size decrease downstream.
• What is abrasion in the context of river erosion?

  Abrasion is the wearing away of the bed and bank by the load carried by a river.
• What is attrition in river processes?

  Attrition is the wearing away of the load carried by a river, creating smaller, rounder particles.
• What is hydraulic action in river erosion?

  Hydraulic action is the force of air and water on the sides of rivers and in cracks.
• What does solution (or corrosion) refer to in river processes?

  Solution refers to the removal of chemical ions, especially calcium, which causes rocks to dissolve.
• How does load affect erosion in rivers?

  The heavier and sharper the load, the greater the potential for erosion.
• How do velocity and discharge influence erosion?

  The greater the velocity and discharge, the greater the potential for erosion.
• What effect does gradient have on the rate of erosion?

  Increased gradient increases the rate of erosion.
• How does geology influence erosion in rivers?

  Soft, unconsolidated rocks, such as sand and gravel, are easily eroded.
• How does pH affect the rate of solution in rivers?

  Rates of solution are increased when the water is more acidic.
• What human impacts can increase the rate of erosion in rivers?

  Deforestation, dams, and bridges interfere with the natural flow of a river and increase erosion.
• What are the main types of transportation in rivers?

  • Suspension: small particles held up by turbulent flow
  • Saltation: heavier particles bounced along the river bed
  • Solution: chemical load dissolved in water
  • Traction: heaviest material dragged along the river bed
  • Floatation: leaves and twigs carried on the surface
• What does the capacity of a stream refer to?

  The capacity of a stream refers to the largest amount of debris that a stream can carry.
• What does competence refer to in river systems?

  Competence refers to the diameter of the largest particle that can be carried by a stream.
• What is critical erosion velocity?

  Critical erosion velocity is the lowest velocity at which grains of a given size can be moved.
• What are the three important features on Hjulström curves?

  1. The smallest and largest particles require high velocities to lift them.
  2. Higher velocities are required for entrainment than for transport.
  3. When velocity falls below a certain level, particles are deposited.
• What is a river regime?

  A river regime is the annual variation in the flow of a river.
• What factors influence the character or regime of a river?

  The amount and nature of precipitation, local rocks, and vegetation cover influence a river's regime.
• How does increased precipitation affect rivers?

  Increased precipitation makes rivers more likely to be affected by solution.
• How are waterfalls formed?

  Waterfalls are formed when soft rock is undercut by hydraulic action and abrasion, causing collapse.
• What are the conditions for deposition in rivers?

  • Deposition occurs as a river slows down and loses energy.
  • Common during flooding, entering the sea, or behind a dam.
  • Larger particles are deposited first, followed by smaller ones.
• What are floodplains?

  Floodplains are flat areas found in the lower parts of a river, comprising clay, silt, or alluvium deposited during floods.
• How do levees form during flooding?

  Levees form when a river floods and deposits coarser material first, creating raised banks.
• What materials make up levees and floodplains?

  Levees are built up of coarse material like sand and gravel, while floodplains consist of fine silt and clay.
• What is a meander in river systems?

  A meander is a normal behavior of fluids and gases in motion, occurring in rivers.
• What factors influence the development of meanders?

  Meander development is influenced by channel slope, discharge, and load.
• What is the sinuosity ratio of a river?

  A river is said to be meandering when its sinuosity ratio exceeds 1.5.
• What are the main forms of deltas?

  • Arcuate: many distributaries branching out radially.
  • Cuspate: a pointed delta formed by a dominant channel.
  • Bird’s foot: long, projecting fingers at the end of distributaries.
• What factors affect the formation of deltas?

  The amount and size of load, salinity, gradient of coastline, vegetation, and energy levels influence delta formation.
• What is a storm or flood hydrograph?

  A storm or flood hydrograph shows how a river changes over a short period, indicating its response to rainfall.
• What does the rising limb of a hydrograph indicate?

  The rising limb indicates the amount of discharge and the speed at which it is increasing.
• What is peak flow in a hydrograph?

  Peak flow is the highest discharge recorded during a storm or flood event.
• What is lag time in the context of hydrographs?

  Lag time is the time interval between peak rainfall and peak discharge.
• What is base flow in a hydrograph?

  Base flow is the seepage of groundwater into the channel, providing long-term discharge.
• What factors affect the recessional limb of a hydrograph?

  The recessional limb is influenced by basin size, geological composition, and behavior of local aquifers.
• How does climate affect flood hydrographs?

  Climate affects flood hydrographs through rainfall total, intensity, and seasonality.