Geography

• Drainage basin


  An area of land drained by a river and its tributaries
• Watershed

  The line that divides two drainage basins, usually a range of hills
• Source


  The starting point of a river
• Mouth


  Where the river enters the sea
• Tributary


  A smaller river that joins a bigger one
• Confluence


  Where two rivers join
• Oxbow lake


  Parts of a river end that have become cut off from the rest
• Marsh


  An area of low-lying land which is flooded in wet seasons or at high tide
• Meander


  A massive bend in the river
• Waterfall


  Rivers sometimes have large waterfalls across them
• Valley


  A low area of land between hills or mountains
• Types of river erosion

  • Attrition
  • Abrasion
  • Hydraulic action
  • Solution
• Attrition


  Pieces of rock hit against each other, breaking into smaller pieces and becoming smoother
• Abrasion


  The grinding of rock fragments caused by a river against the bed and banks, widening and deepening the river
• Hydraulic action

  The sheer force of the water, which can undermine riverbanks on the outside of a meander or force air into cracks
• Solution


  The process by which river water chemically reacts with soluble minerals in rocks and dissolves them
• Types of river transport

  • Traction
  • Saltation
  • Solution
  • Suspension
• Traction

  Rolls the heaviest rocks along the river bed
• Saltation


  Medium-sized rocks bounce along the river bed
• Solution


  Some chemicals dissolve in the water
• Suspension


  Smallest particles are carried along in the water
• Deposition takes place when a river slows down and no longer has the energy to carry the materials it is transporting
• Larger rock fragments are dropped first due to their greater weight, while finer materials are deposited later when the river has even less energy
• Formation of a waterfall

  1. Water flows over two layers of rock, eroding the softer rock faster than the hard rock

  2. The bed of the river gets steeper, and the flow of water becomes steep enough to be considered a waterfall

  3. Water continues to fall against a back wall, which also continues to wear away under cutting the soft rock and creating an overhang

  4. Enough water moving over one hard rock will undercut it and break it away, causing big pieces of rock to collapse and fall into the plunge pool, which makes it even bigger and deeper than before through abrasion and hydraulic action

  5. As hard rock is slowly eroded by the constant flow of water, it falls into the plunge pool and creates a large gorge
• Types of rocks

  • Metamorphic
  • Igneous
  • Sedimentary
• Metamorphic rocks


  Igneous or sedimentary rocks that are altered or changed by heat and pressure, without melting
• Metamorphic rocks


  • Marble
  • Slate
• Igneous rocks


  • Basalt
  • Granite
• Sedimentary rocks


  • Limestone
  • Sandstone
• Metamorphic rocks sometimes contain fossils, but they are usually squashed out of shape
• Factors affecting where we live

  • Positive: Pleasant climate, good water supply, good soil for farming, established medical facilities, flat or gently sloping land, good food supply
  • Negative: Too hot or too cold, dense forest, poor transport links, poor soils for farming, steep slopes, too wet or too dry, lack of investment, wars and fighting, few natural resources
• Factors affecting birth and death rates

  • Positive: Good healthcare, medicine, better education, vaccinations (young-age), clean running water and sanitation, healthy lifestyle
  • Negative: War, natural disasters, diseases
• Several storms hit the UK, bringing lots of rainfall and strong winds, with 400mm of rainfall falling in less than two months, 200mm above normal levels
• The rivers were usually cleared out, making the river deeper, but this hadn't been done in years, making the risk of flooding higher
• Sedimentary


  The river transport bits of rock, and deposit them on the bottom of the river bed. Deposited rocks build up in layers, and the weight of the top layers compresses the bottom layers. The compression squeezes out water leaving the salt crystals that cement the rocks together.
• Sedimentary rocks


  • chalk
  • limestone
  • shale
  • sandstone
• Igneous


  The inside of the earth is very hot - hot enough to melt rocks. Molten (liquid) rock forms when rocks melt. The molten rock is called magma. When the magma cools and solidifies, a type of rock called igneous rock forms.
• Basalt


  • Cools quickly. It forms from explosions and is called extrusive igneous rocks. They have small crystals.
• Granite


  • Cools slowly. It forms underground and is called intrusive igneous rocks. They have large crystals.
• Some villages were completely surrounded by the flood for weeks and elderly people struggled to access clean water and food, dozens of people were evacuated