Rivers Gcse geography

• Source - start of the river
• Mouth - end of the river
• Tributary - a small river that feeds into a larger river
• Confluence - where two rivers meet
• Watershed - boundary between one drainage basin and another
• River channel - part of the river that holds the water
• Catchment area - an area of land that a river system drains
• Drainage Basin - the area of land drained by a river and its tributaries. The catchment area or the river basin.
• Hydraulic Action - the water is forced into cracks and traps the air which causes pressure to build up causing mini explosions that break the rock
• Attrition - rocks being carried by water smash together and break into smaller particles
• Solution (erosion) - some rocks are soluble so the river water erodes then by dissolving bits of the rock
• Abrasion - the water flings sand , pebbles and large rocks during storms at the base of cliffs which wears land away
• Erosion - wearing away of land by the sea
• Transportation - movement of sediment by sea
• Suspension - fine materials such as clay and sediment are carried by the sea
• Solution(transportation) - dissolved minerals are carried by the sea
• Traction - large boulders and pebbled are rolled along the sea bed
• Saltation - small stones , pebbles and slit bounce along the sea bed
• Deposition - sediment is dropped by the river
• UPPER - Vertical erosion by hydraulic action with mostly traction
• MIDDLE - less vertical and more lateral erosion due to attrition abrasion and solution with suspension and traction
• LOWER - little erosion with only lateral occurring and suspension and solution
• Interlocking Spurs - River erodes vertically but doesn’t have the energy to widen channel at this point so river winds around bands of hard rock which are known as interlocking spurs
• Weathering - breaking down of rocks in situ
• V-shaped valley - found in the upper course where the river erodes vertically giving the valley a narrow base and the sides become unstable and freeze thaw and chemical wearing works away at sides giving a v-shaped appearance
• Carbonation - where weak carbonic acid attacks rock
• Hydration - where water swells the structure of rock
• Meander - the outside bend flows fastest as it has the furthest to travel so the energy is high so abrasion, hydraulic action undercut the outside creating a river cliff. On the inside bend , the flow is slower so deposition occurs creating a slip off slope.
• Oxbow Lake - Erosion on outside and deposition on inside leads to meander changing . Erosion narrows neck of the land so meander moves closer together. When there is high discharge river cuts across the neck and takes a shorter route. Deposition cuts off original meander
• Floodplain - a floodplain are flat areas of land covered mainly by grass which when there is a flood will be filled by water
• Floodplain- during a flood water contains river silt that pours over valley depositing sediment which slightly rises the floodplain. Also, when the outside bend meets edge of river valley erosion will cut into it which widens the valley as their position moves downstream.
• Levees - during a flood silt is transported and sediment is graded as fairest sediment deposited on channel edges and thinnest are deposited over outer parts as wetted perimeter increases. Therefore, natural levees build up
• Estuary - a wide sheltered body if water at the rovers mouth . It combines salt water and fresh water. As river meets the sea at high tide it causes deposition so mudflats and salt marshes form in these areas . Mudflats only seen at low tide and can over time be colonised by halophytes
• Human causes for flooding : Impermeable surfaces don’t allow infiltration which increases surface run off so lag time will shorten which increases risk of flood
• Aim - To investigate changes in a river as you move downstream
• Hypothesis- bed load size increases as you move downstream
• Ranging poles method : 1. Place the ranging poles either side of the river channel to create a transect 2. Pick up ten pieces of bed load using random sampling within transect 3. use a 30cm ruler to measure the long axis of rocks 4. Record measurements
• The location is only an hour away from the school and 40.5 miles away which allows us to travel back in case of emergency and it reduces cost
• With the location we can investigate 4 sites across the long profile.However, it isn’t enough as you should have gone to at least 20 sites.