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River environments - Coggle Diagram

- - - - the point at which a tributary joins the main river
    - - this marks the edge of a drainage basin
    - - this is the point at which a river enters the sea
- - - - lag time
        
        the time between peak rainfall and peak discharge
      - rising limb
        
        the start of the storm is a slow rise in discharge as only small amounts of water falls into the channel. this is the upwards line on the graph
      - falling limb
        
        the discharge starts to all slowly as water is added from throughflow and groundwater flows which are much slower. this is the downwatrd line on the graph
      - base flow
        
        the base flow supplies the river with water between storms and the minimum amount of water needed to keep the river flowing
    - - vegetation cover
        
        more vegetation means high rates of interception meaning less surface run-off meaning a longer lag time
      - relief/slopes
        
        high slopes means more surface run off meaning shorter lag time
      - rainfall intensity and duration
        
        lots of rainfall means more water meaning more surface run off meaning a shorter lag time
      - land use
        
        more urbanisation means more concrete (impermeable) meaning more surface run off as there is less infiltration so a shorter lag time
      - geology
        
        softer rock types means more infiltration meaning less surface run off meaning a longer lag time
      - temperature
        
        low temperature means snow which takes longer to melt, meaning more surface run off but longer lag time
      - lakes and reservoirs
        
        interventions which hold back discharge means less surface run off and a longer lag time
      - drainage basin
        
        more tributaries means more surface run off so water reaches a river slower so longer lag time
      - soil type and depth
        
        deeo soils means more water stores so more throughflow so less surface run - off so a longer lag time
- - - - the atmosphere
      - the land
      - the sea
  - - - water is converted from a liquid into a gas
    - - when plants take up liquid water from the soil and 'breathe' it into the atmosphere as water vapour
    - - when water vapour cools and changes from a gas to a liquid
    - - transfer of water in the form of rain, hail, sleet or snow from the atmosphere to the land or sea surface
    - - the movement of water over the ground surface until it eventually enters the sea, river of lake
    - - the vertical transfer of water downwards through rock into the aquifer or groundwater store
    - - when water moves slowly under the influence of gravity horizontally through the soil until it reaches a stream or river
    - - this takes place in the aquifer and is the horizontal underground transfer of water to rivers, lakes and the sea
    - - the vertical movement of water from the surface into the soil
- - - - A small stream will naturally follow small' depressions in the landscape. As the small stream flows downhill steeply, the bedload will erode downwards and
        scrape away the bottom of the channel (vertical erosion). This vertical erosion deepens the valley, making the sides steeper and exposed. Over time, weathering and gravity wear away the steep valley sides, forcing
        material into the stream, which it uses to cut the valley deeper.
    - - Interlocking spurs are projections of high land that alternate from either side of a V-shaped valley. They are formed by fluvial erosion and are found in the upper course of a river where rocks are hard. Formed when the river is small and has less erosive power. It does not remove the hillsides (spurs) but instead winds around them. Erosion is vertical and headwards (towards the mouth).
    - - waterfalls occur when harder rock overlays softer rock. Over time, as the soft rock is eroded, is is undercut and a ledge of hard rock is formed, as well as a plunge pool. the ledge collapses and the debris is used in abrasion to speed up the process. this is repeated over many years and as the waterfall moves upstream, a gorge is formed
  - - - as the river erodes, horseshoe like loops are formed, called meanders. these gradually migrate downstream and a river cliff and slip-off slope are formed. over time, the horse shoe becomes tighter until the ends become very close together. as the river breaks through, and the ends join the loop is cut-off from the main channel. the cut off section is called an oxbow lake
  - - - the tidal part of a river, where freshwater river meets the salty ocean, resulting in brackish water
      - estuary vs delta
        
        a delta forms triangular deposits whereas the estuary forms minimal deposits
        
        deltas formed in regions of low tides, whereas an estuary is formed in areas of high tide
        
        deltas are fertile land, estuaries are not
    - - this is a wide area of flat land found on either side of a river. when a river floods, it deposits silt. layers of silt build up to provide a thick layer of fertile alluvium, making these areas perfect for farming
    - - a levee is a raised river bank formed after many flood events. when the river overflows its banks, the velocity decreases and sediment is deposited. larger material is deposited closer to the river and finer silts are carried further. over the years the levees are raised
- - - - steeply sloping towards the lower section of the river
    - - shallow slopes towards the mouth of the river
    - - almost flat, at sea level, very gentle sloping towards its mouth
    - - channel width and depth
        
        increase as you go downstream as the velocity f the river is faster meaning increases energy, therefore increased erosion so wider and deeper river channel
      - gradient
        
        decreases as you go downstream as the source of the river is in mountainous areas, which have a high gradient, which uses vertical erosion. as it travels down, the gradient slopes as it gets closer to the sea
      - velocity
        
        increase as you go downstream as more energy is lost through friction on the bed and banks, whereas in the lower cource, there is a lot larger space, meaning less water is touching the bed and banks
      - discharge
        
        increases as you go downstream and the channel depth and width is bigger, so more erosion takes place, making it wider so more water can flow. tributaries also join
  - - - steep sided v-shaped valley. thin river channel and shallow
    - - V-shaped valley remains with a wider valley floor and the river begins to meander across it. the river channel begins to widen and becomes deeper
    - - wide, shallow valley with large flood plains and meanders. the river channel is wide, deep and smooth sided