- Created by: Pheebie
- Created on: 28-04-12 15:18
FLOWS: Through-flow, surface run-off, infiltration, percolation, groundwater flow and channel flow.
STORES: Interception, surface-storage, vegetation storage, soil water storage, groundwater storage and channel storage.
OUTPUTS: Transpiration, evaporation, river run-off.
Factors that effect storm Hydrographs
- Rock type
- Land use
- Drainage density
- Precipitation/ Tempreature
- Tidal conditions
- Rainfall factors
River Erosion Processes
Hydraulic Action: Turbulent flow lifts sediment out of the river banks leading to undercutting and eventual bank collapse.
Abrasion (Corrasion): Sediment scouring or rubbing along bed or bank from fine particles to boulders, eroding it.
Attrition: Reduction in particle size as they knock into each other becoming smaller and rounder further downstream.
Corrosion: Rocks dissolve in the water e.g. carbonate rocks (limestone/ chalk.)
River Transportation Processes
Traction: Boulders and rocks are rolled along the river bed.
Suspension: Fine particles are carried along by rive resulting in muddy colour of river.
Saltation: Smaller pebbles and rocks "Bounce" along the river bed.
Solution: Minerals e.g. carbonates (chalk/ limestone) are dissolved in the river.
Lower and Upper course of river Comparison
Upper Reaches Lower Reaches
Low discharge High Discharge
Coarse Sediment load Finer sediment load
Steep gradient Gentler gradient
Vertical erosion dominant Lateral erosion dominant
Head ward erosion also occurs
Closed V-shaped valley Open U-shaped valley
Meander Cross Section
Ox Bow Lake Formation
Meanders Vs Braided Channel
Less load Large load
Fine load Coarse load
Cohesive Banks Crumbling banks
Gentle slope Steep slope
Long Profile of a River
Cross Profile of a River
Rejuvination of a River
Carlisle Floods January 2005 (1)
Short term responses
- Resulting from 175mm of rain in 36hours.
- 3 dead.
- 125 Injured.
- Communication effected.
- 300 premises flooded
Carlisle Floods January 2005 (2)
Long term Impacts
- Homes had to be rebuilt.
- Some people who were uninsured were left homeless.
- Business trade was lost.
- Emotional impacts upon people.
- Final bill was nearly £250 million.
Causes of Bangladesh floods:
- Snow melting from the Himalayas..
- 80% of Bangladesh is a floodplain.
- Silt blocks river channels and make it difficult to discharge.
- Heavy monsoon rainfall.
- Trees have been cleared for rainfall.
- Two big rivers (Ganges and Brahmaputra) join in Bangladesh.
- 70% of land is less than 1m above sea level so water can't drain away.
- Cyclones coming of the see and huge rains in monsoon seasons.