Unit 1- Floods Flashcards
x6
Where is water stored?
-Atmoshpere
-Vegitation
-Ground surface
-Soil
-Rocks
-Rivers/lakes
What is infiltration?
Water flows into soil
What is throughflow?
Water flows in soil underground due to gravuty
What is overland flow/surface run-off?
water flowing on surface
Wha is groundwater flow?
Water flowing in bedrock
What is precolation?
Water flows deeper into soil/ to bedrock
What is interception?
Water stopped/slowed by branches/canopy
What is a flash flood?
-High rainfall in short time
-sudden rise in water levels
What does a hydrograph show?
-River discharge over a period of a flood
What is the tall/steep line and the gradual decrease line on a hydrograph called?
-Rising limb
-Falling limb
What cuases the lag time?
-Slow water movement into river
-Groundflow/Throughflow
x3
Why do rivers flood (human)?
-Urbanisation (impermeable surfaces)
-Frozen or baked soil (impermeable)
-Afforestation (decreases lag time)
What is Soft engineering?
- Natural appraoch to maintenance
- Does not include artificial builings
- Often cheaper
x5
Soft engineering for rivers?
Washlands
Afforestation
River restoration
Flood plain zoning
Do nothing
What is Hard engineering?
-Artificial builing
-Often more expensive
-Often better results
x4
Hard engineering for rivers?
Flood relief channels
Channelisation
Building dams/ reservoirs
Embankments
What and why is doing nothing good a positive and negative management for flooding?
DESCRIPTION:
Letting the river flood naturally
POSITIVE:
-Deposition makes fertile soil
NEGATIVE:
-Can be damaging
What and why is afforestation a positive and negative management for flooding?
DESCRIPTION:
Vegetating/ planting trees around a river
POSITIVE:
-More interception and therefore less discharge
-Less soil erosion
-Low cost
NEGATIVE:
-Takes time for trees to grow
-Disrupts hydrobiological cycle
What and why is washlands a positive and negative management for flooding?
DESCRIPTION:
An area of land where water can flow into if there is a flood
POSITIVE:
-Slows flooding
-Creates fertile soil
NEGATIVE:
-Limmits land use in some areas ( as it will flood)
What and why is river restoration a positive and negative management for flooding?
DESCRIPTION:
Restores a rivers biodiversity in hopes it will prevent flooding.
POSITIVE:
- Natural
- Sightly
NEGATIVE:
- Flooding may still occur
- Changes to land could be negative
What and why is river **flood plain zoning **a positive and negative management for flooding?
DESCRIPTION:
The government stops building on places with flood risk
POSITIVE:
- Prevents damage to buildings in flooding
- Flooding isn’t costly as buildings aren’t destroyed
NEGATIVE:
- Not possible in already established cities
What and why are flood relief channels a positive and negative management for flooding?
DESCRIPTION:
A channel is built next to a river to contain the extra discharge when floods occur.
POSITIVE:
-Prevents overflow
NEGATIVE:
- Costly
-Unsightly
- Often unused ( floods aren’t that common)
What and why are flood is channelisation a positive and negative management for flooding?
DESCRIPTION:
River course is deepened and straightened
POSITIVE:
-Allows room for more discharge
NEGATIVE:
- Causes flooding downstream instead
- Costly
- Erosion downstream due to more water
What and why is building dams and reservoirs a positive and negative management for flooding?
DESCRIPTION:
Structures (walls) are built to hold water e.g in artificial lakes
POSITIVE:
-Store water
-Can be used for hydroelectricity and drinking water
NEGATIVE:
-Expensive
-Unsightly
-Floods can still occur
