Rivers, Floods And Managment Flashcards
What is vegetation storage?
Water that is stored in plants.
What does Transpiration mean?
Evaporation of water from plants.
The definition of Evaporation is?
Water that is heated by the sun and turns it in to water vapour.
Define the term stem flow?
Water running down stems and branches during and after rainfall to reach the ground.
Precipitation is…?
Water in any form that falls from the atmosphere. (Snow, rain, hail)
What does interception mean?
Process where rain is prevented from directly reaching the ground, can evolve vegetation.
Explain ground water storage?
When water is stored underground.
Infiltration is defined by…?
The soaking of water in to the soil (ground)
What does surface storage mean?
Where water is stored in places, such as lakes, reservoirs and puddles!
Define ground water flow?
Movement of water flowing slow below water table through permeable soil.
What is Percolation?
This is where water moves vertically down through soil in to the water table.
Through flow is…?
Water in soil flows down slopes and hills due to gravity.
What is mean by channel storage?
Volume of water held in a river in the drainage basin.
River runoff mean?
All water entering a river eventually flows out of the drainage basin.
What’s actual Evapotranspiration (AET)?
Amount of water lost at the time of evaporation and transpiration.
What is potential Evapotranspiration (PET)?
Amount of water lost assuming a continual supply of water is given.
Soil moisture utilization (U) is…?
When vegetation uses water stored as soil (common in winter).
What is mean by soil moisture surplus (S)?
When precipitation is greater than AET.
Explain soil moisture density (D)?
When there is NOT enough water for vegetation to survive.
Define soil moisture recharge (R)?
When there is enough precipitation to restore.
Field capacity is when…?
Maximum capacity of soil in terms of water.
What’s peak discharge?
This is the highest point on the graph when the river is at its greatest.
Lag time???
The delay between peak rainfall and peak discharge.
Part of the hydrograph that increases up to the peak discharge?
Rising limb.
Part of the hydrograph that decreases after peak discharge?
Falling limb.
What 7 physical factors affect the storm hydrograph?
1. Drainage Basin characteristics
(size, shape)
2. Antecedent Conditions
3. Rock Type
4. Soil Type
5. Vegetation
6. Precipitation
7. TemperatureWhat 2 main human factors affect the storm hydrograph?
- Urbanized impermeable rock (concrete)
2. Man made drainage systems
What are the 5 main river erosion happens?
- Hydraulic action
- Abrasion
- Attrition
- Corrosion
- Cavitation
What are the 4 ways a river transports its load?
- Solution
- Suspension
- Saltation
- Traction
What are the 3 processes the Hjulstrom curve graph?
- Erosion
- Transportation
- Deposition
What is a drainage basin?
Area of land, bordered by a watershed, drained by a river and its tributaries
What is the watershed?
Boundaries of a drainage basin
How does precipitation lead to flooding?
- Prolonged rainfall or heavy rainfall.
2. Snow acting as a store of water then melting
What is overland flow?
This is rapid form of water transfer over the surface of the ground
When will overland flow most likely happen?
- During heavy periods of rainfall
2. When the soil has become completely saturated.
What is permeable rock?
Rock which can absorb water or allow water to pass through the cracks and joints
What does vegetation do yo water transfer and why?
Vegetation slows it down. Some water is lost by evaporates purgation while some water is used for plant growth.
What causes a high runoff?
- Lack of trees
- Saturated soil
- Impermeable rock
What is impermeable rock?
Rock which cannot absorb water
Factors effecting the rivers discharge?
- Distance downstream
- Climate change
- Land use
- Water absorption
- Channel modification
What is a storm hydrograph?
A graph that shows the discharge of a river following a storm event.
The amount of energy available in a river to do ‘work’ depends on…..
- Height the water has to descend (gravity)
2. The mass of the water available
When the water starts to move downhill________energy is conveyed in to ________energy.
- First Potential
2. Converted in to kinetic
What is the rivers load?
The sediment carried by a river.
What is solution?
The transport of chemicals dissolved in the water. e.g. Calcium carbonate
What is suspension?
Fine grained silts and mud which is carried in the main body of the water. (Makes the river look muddy and murky).
What is traction?
Large material rolling along the river bed. E.g. Boulders.
What is saltation?
Material moving in a series of small bounces along the river bed (leapfrog!!) e.g. Pebbles
What even is erosion?
The picking up and removal of material in the river
When does erosion occur?
When the river has surplus energy available.
What is abrasion?
When particles of rock carried by the river scrape away at the river bed and banks. This dislodges rock to add to the load of the river (sandpaper effect).
What is hydraulic action?
When the power of moving water is able to dislodge loose particles of rock from the riverbed or banks.
