Zusammenfassung der Ressource
Rivers Floods and Management 1
- The Hydrological Cycle
- Open System
- Watershed
- Boundary of the drainage basin
- Inputs
- Precipitation
- Storage
- Interception
- Vegetation storage
- Groundwater storage
- Channel storage
- Flows and Processes
- Suface Runoff
- Water flowing over the land
- Infiltration
- Water soaking into the soil
- Groundwater flow
- Water flowing slowly in the water table
- Throughflow
- Water moving slowly downhill through the soil
- Percolation
- water seeping through the soil
- Outputs
- Evaporation
- water turning from a liquid to a gas
- Transpiration
- Evaporation from the leaves
- Evapotranspiration
- evaporation and transpiration together
- Water balance
- water surplus --> water depletion --> water recharge
- River Discharge
- The volume of water flowing in a river
- Hot weather can cause a decrease in river
discharge as more is being evaporated
- Abstraction can cause a reduction in discharge
- Storm Hydrographs show river discharge over time
- Rock type affects lag time and peak discharge
- Soil type affects lag time and peak discharge
- Precipitation affects peak discharge
- Temperature affects peak discharge and lag time
- The Long Profile
- Types of Erosion
- Abrasion
- Eroded pieces of
rock srape and rub
against the bed, the
sandpaper effect
- Hydraulic action
- The pressure of water breaks off rock
partiles away from the beg
- Corrosion
- The dissolving of rock by chemical processes.
- Transportation and Deposition
- Solution
- Dissolved material being carried along
- Suspension
- Silt and Clay are carried along in the water
- Saltation
- Material bouncing along the river bed
- Traction
- Large boulders roll along the river bed
- Deposition occurs when the river
doesnt have enough energy, this can
occur when the discharge decreases
- The Hjulstrom Curve
- The link between the
rivers velocity and the
competence
- Channel Charateristics
- Long Profile
- Shows the gradient of the river channel as the distance increasing
- The velocity and discharge of a river
increases as you go downstream
- Effiiency is measured by hydraulic radius
- Upper Stage
- Steep V shape. High
Vertical Erosion.
Large particles are
transported. Little
deposition.
- Middle Stage
- Wider Valley. More
later erosion.
Deposition causes
floodplain. particle
size decreases
- Lower Stage
- Very Wide Valley. Low turbelance. Smaller Particles