Geography: Theme A: Rivers

• Water Cycle


  The continuous circulation of water between land, sea and air
• Drainage basin


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


  A form of moisture in the atmosphere such as rainfall, sleet, snow, etc.
• Interception


  • The process whereby precipitation is prevented from falling onto the ground by plants
• Surface runoff/overland flow


  The movement of water over the surface of the land
• Infiltration


  The movement of water from the surface into the soil
• Throughflow


  Water moving through the soil
• Percolation


  The movement of water from the soil to the bedrock
• Groundwater flow


  Water moving horizontally through the bedrock
• Evapotranspiration


  When water is transferred from the land to the atmosphere by evaporation
• Watershed


  The boundary between drainage basins
• Source


  The starting point of a river, which may be a lake, glacier or marsh
• Tributary


  A stream which flows into a larger river
• Confluence


  The point where two rivers meet
• River mouth


  The end of a river where it meets the sea or ocean
• Gradient


  • The slope over which the river loses height
• Depth


  • The distance from the surface of a river to the river bed
• Width


  • The measurement from one bank of a river to the other across the river
• Load


  The sediment carried by a river
• River discharge


  The amount of water in a river which is passing a certain point at a certain time, measured in cubic metres
• Erosion


  The wearing away of the landscape by ice, water or wind
• Attrition


  • A process of erosion where transported particles hit against each other, making the particles smaller and more rounded
• Abrasion/corrasion


  • A form of erosion caused by the grinding of rock fragments carried by a river against the bed
• Hydraulic action


  • A form of erosion caused by the force of moving water
• Solution/corrosion


  The process by which water reacts chemically with soluble minerals in the rocks and dissolves them
• Suspension


  The transportation of the smallest load e.g fine sand and and clay, which is held up continually within river or seawater
• Saltation 


  The bouncing of medium sized load, like small pebbles and stones, along the river bed
• Traction 


  The rolling of boulders and pebbles along the river bed
• Deposition 


  The dropping of materials on Earth's surface
• River landforms


  Large scale features found along the course of a river, such as waterfalls and meanders
• Waterfall


  A steep fall of river where its course crosses between different rock types, resulting in different rates of erosion
• Meander 


  A river landform. Asweeping curve or bend in the river's course
• Slip-off slope


  A small feature seen on the outside of some meander bends which is caused by erosion of the river bank
• River cliff


  The outer bank of a meander in a water channel, which is continually undergoing erosion
• Floodplain


  An area of low-lying ground adjacent to a river, formed mainly of river sediment and subject to flooding
• Levees


  Raised banks along a river that help to reduce the risk of flooding
• Flooding 


  A temporary covering by water of land which is normally dry
• River management strategies


  The management of water resources of a basin a part of the natural ecosystem and in relation to their socio-economic setting
• Hard engineering methods

  Strategies to control a natural hazard which does not blend into the environment
• Soft engineering methods


  A strategy to control a natural hazard which does blend into the environment so is often sustainable