GCSE Geo- rivers

GCSE Geo- rivers

1. Hyrographys

   • vocab
     • discharge: the colume of water pasing a given point in a river at any moment in time
     • lag time: the time it takes for rainfall to get to the river
     • falling limb:water is still reaching the river but in decreasing amounts
     • rising limb:the normal flow of the river starts to rise
     • Flashy responce: river that responds quicky to rain to is has a high peak and short lag time
   • Built up area
     • Higher Discharge
       • Due to: artificial surfaces - tarmac and concrete= less surface run off
     • Short Lag time
       • Due to: little interception by vegetation etc
       • little infiltration (small amounts of vegetation )
     • Flashy Responce
       • faster response = higher peak discharge
   • Forested Area
     • long lag time
     • low discharge
       • - Infiltration high. -Ground water flow slower than surface run off. -Water flows slower over vegetetation
     • subdued responce
       • slower response = lower peak discharge

2. CASE STUDIES - FLOODING

   • Bangledesh
   • CockerMouth

3. Hard/Soft Engeneering

   • HARD
     • Dams
       • disadvantages
         • resettlement
         • very expensive
         • Habitats effected
       • Advantages
         • turbines can be built into the dam to generate hydroelectric power
         • steady water release allows irrigation to land
         • the resevoir can be used for recreational water sports
     • Straightening and deepening of rivers
       • disadvantages
         • Flooding may happen downstream because flood water is carried there faster
         • more erosion occurs downstream
       • advantages
         • it time less time to nivagate the river because the channel is shorter
         • we can harness the extra power to make electricity
     • Levees
       • advantages
         • they allow flood plain to be built on
         • the river can hold mor water
       • disadvantages
         • they are quite expensive
         • if breached = risk of severe flooding
     • Others
       • Diversion spillways
       • Flood walls
       • Storage areas
   • SOFT
     • -Forecasts and Warnings -Preperation
       • advantages
         • enables time to evacuate = lives + possessions saved
         • sustainable + cheap
       • disadvantages
         • cannot always predict floods/ danger
         • people may ignore warnings
     • Floodplain zoning etc
       • advangages
         • there are no new buildings/ roads etc to be damaged so impact of flooding reduced
         • lives/ property saved
       • disadvantages
         • its restrics development ( big problem when there is a shortage on housing
         • it cant be used in areas that are already urbanized
     • Afforestation + Reforestation
       • disadvantages
         • takes time
         • large areas required to be effective/ land that could have been used for economic activity
       • advantages
         • very effective long term
         • creates wildlife habitats
         • vegetation protects against soil erosion

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