geography paper 1 section c

• hydraulic action


  when the sheer force of fast flowing water hits the river banks and beds and forces water into the cracks
• abrasion

  small boulders and stones may scratch and scrape their way down a river during transport wearing down the river banks and bed
• attrition


  stones colluding with each other to knock off jagged edges to become smooth and rounded as they are transported downstream. smoother and more rounded means longer in the river
• solution


  dissolving of rocks with a chemical reaction to erode them
• traction 


  moving large boulders and rocks along the river bed, too large to be carried by the current
• saltation


  bouncing small pebbles and stones along the river bed
• suspension


  finer particles carried within the rivers flow
• deposition 


  process by which a river drops its load
• gorge


  vertical narrow steep sided valley, usually found immediately downstream of a waterfall. it is formed by gradual retreat of waterfalls over hundreds of years
• interlocking spur


  projections of high land that alternate from either side of a v shaped valley. they are formed by fluvial erosion and found in the upper course of a river
• waterfall


  sudden drop of the river. it forms when there are horizontal bands of resistant rock over exposed less resistant rock.
• what happens to the soft rock of a waterfall 


  it is undercut until the hard rock overhang collapses and falls into the plunge pool.
• tributary


  small stream that joins a larger river
• source


  start of the river
• watershed


  edge of a river basin
• drainage basin


  area of land drained by a river
• mouth 


  end of a river
• meander


  bend in the river found in lowland areas of the middle course
• how do meanders grow


  high velocity flow is more powerful than low velocity, the high velocity causes erosion which undercuts the river.
• thalweg 


  line of fastest flow
• riffle 


  shallow area
• pool


  deeper section of the river
• helicoidal flow


  a motion that corkscrews across from one bank to another.
• slip off slope


  where sand and pebbles are deposited on the inside bank where the current is slower forming and gentle slope
• river cliff


  where the bank has been undercut on the outside of the bend
• sinuous 


  a river with many meanders
• what does dine in eat out mean


  deposition is in the inside bend, erosion is on the outside bend
• estuary


  mouth of the river where the river meets the sea, water level is tidal
• flood plain 


  layers of silt builds up forming a deposit of alluvium
• levée


  naturally raised river banks prone to flooding

  
• what is the example for every landform in a river


  river tees
• what are the human factors affecting flood risk


  deforestation

  agriculture

  urbanisation
• what are the physical factors affecting flood risk

  precipitation

  relief

  geology
• how does deforestation affect flood risk


  more water is available and transfers to rivers. this is because lots of water is held in trees
• how does geology affect flood risk


  impermeable rocks encourage water to flow over land and into river channels. more water in a river leads an increased chance of flooding
• what does a hydrograph show


  volume of water flowing along a river in its discharge. they plot river discharge after a storm.
• what is the time between peak rainfall and peak discharge on a hydrograph called


  basin lag time
• what are the two limbs of storm flow on a hydrograph called


  rising limb and recession limb
• what does a flashy hydrograph say about a river


  small basin, impermeable rocks and urbanisation transfers water into the river channel quickly
• what does a low flat hydrograph say about a river


  large basin with permeable rocks, forests and dry soil to absorb most of the excess water