Rivers and Coasts

• Attrition is a type of river erosion that occurs when rocks and sediment carried by the river collide and break into smaller pieces.
• Hydraulic action is a type of river erosion that occurs when the force of the water against the riverbed and banks dislodges and carries away loose material.
• Sediments are small particles, such as sand or gravel, that can be transported by water.
• Solution is a type of weathering where soluble minerals are dissolved by rainwater, resulting in the breakdown of rock.
• Rivers are formed through the process of erosion, where water wears away the land and carries sediment downstream.
• abrasion - the wearing away of the surface of a rock by the action of water or other agents
• traction - large particles are rolled along the river bed
• suspension - when a liquid is mixed with a solid, the solid particles are suspended in the liquid
• saltation - Small rocks or pebbles which are too big to be carried within the water are transported and bounce along the bottom of the river bed.
• suspension - when a liquid is mixed with a solid, the solid particles are suspended in the liquid
• Hold the line - maitnain or change the current standard of protection to keep the shorline in its current position.
• Integrated zone management - a way to manage the coast and the land behind it sustainably, by involving everyone that uses it in the decision
• Shoreline management plan - a plan which assesses the risk to a piece of coastline and how to manage these.
• No intervention - no investment in defences against flooding or erosion.
• Managed realignment - allow the shoreline to change naturally, but manage and direct the process
• 1. Advance the line - build new defences on the seaward side
• Hard engineering: involves the placement or artificial structures which are used to stop or slow the natural process of erosion, sea level rise and flooding.
• Soft engineering: working with the nature to manage the coastline.
• Natural Flood management (NFM) - is used to manage coastal flood risk and erosion
• Deposition - When the sea loses energy, it drops the sand, rock particles and pebbles it has been carrying.
• Dune fencing - built seaward side of the dunes, fencing inhibits trampling from beach users.
• Dune planting - Plants such as lyme or Marram grass help to stablalise the dunes with their roots.
• Dune thatching - Covering the face of dunes with bundles of straw, branches and even old Christmas trees in some areas, increases sand accretion and protects dune vegetation.
• cliff stabalisation - to reduce the slope of the cliff and revegetate the cliff top. Planting vegetation helps to strengthen the cliff structure and increase cohesion, which will help to keep the cliff in place
• Beach nourishment - This is when the sand is spread over the beach where the erosion is occurring compensate for shore erosion and restore the recreational value of the beach.
• Revetments - are sloping structures built on embankments or shorelines, along the base of cliffs, or in front of sea walls to absorb and dissipate the energy of waves in order to reduce coastal erosion.
• Groynes - Groynes trap sediments from longshore drift so that the coast behind the sand layer is protected from erosion.
• Breakwaters - It reduces incoming wave energy, provides a sheltered beach area
• Sea walls - a solid barrier made from concrete, masonry, or gabions and are designed to prevent high tides and inland flooding
• Long shore drift - Continual swash and backwash transports material sideways along the coast in a diagonal motion.
• Rock Amour - piles of bolders on the coastline to prevent erosion
• Dredging - The process of removing sediment from the bottom of a river or lake deepening it.
• levees

  • Levees occur in the lower course of a river when there is an increase in the volume of water flowing downstream and flooding occurs.
  • Sediment that has been eroded further upstream is transported downstream.
  • When the river floods, the sediment spreads out across the floodplain.
  • When a flood occurs, the river loses energy. The largest material is deposited first on the sides of the river banks and smaller material further away.