River landscapes and processes [Part 3] 🌊 Flashcards
1
Q
What do storm hydrographs show ?
A
- storm hydrographs show the changes in river discharge, around the time of a storm.
1
Q
What does peak discarge mean ?
Hint: storm hydrograph
A
- peak discarge is the highest discharge in the period of time, you’re looking at in a storm hydrograph
2
Q
What does lag time mean ?
Hint: delay
A
- lag time, is the delay bewteen peak rainfall and peak discarge
3
Q
What does rising limb mean ?
Hint: as rainwater flows
A
- rising limb, is the increase in river discarge, as rainwater flows into the river.
4
Q
What does falling limb mean ?
A
- falling limb is the decrease in river discharge, as the river returns to its normal level.
5
Q
What is a dam ?
A
- a dam, is a huge wall that is built across rivers, usually in the upper course.
6
Q
What are two advantages and disadvantages of dams and reservoirs ?
A
- reservoirs reduce the risk of flooding, because they store water (especially during periods of heavy rain)- this means, water can be released in a controlled way.
- ; dams trap sediment which means the reservoir can hold less water.
- dams are also very expensive to build
7
Q
What is channelisation ?
A
- channelisation, is when the river channel is being widended, deepened or straightened. [as this is done to reduce the risk of flooding]
8
Q
What’s an advantage and disadvantage of channelisation ?
Hint: hold more
A
- channelisation means that deeper or wider channels can hold more water.
- ; flooding may happen downstream because water is carried there faster.
9
Q
What’s an advantage and disadvantage of floodplain zoning ?
A
- floodplain zoning is a cheap strategy that reduces the risk of flooding, because impermamble surfaces aren’t created.
- ; due to restrictions [preventing building on parts of a floodplain that are likely to ge affected by a flood], the expansion of an urban area is limited, if there aren’t other suitable buildings.
10
Q
What’ a advantage and disadvantage of washlands ?
A
- washlands reduces the flood risk in areas where floods could cause a lot of damage, because it stores water when river discharge is high.
- ; these flooded areas can’t be then used for anything else such as farming
11
Q
What is floodplain zoning?
A
- floodplain zoning, is when restrictions are put in place that prevent building on parts of a floodplain, that are likely to be affected by a flood
12
Q
What are washlands ?
A
- washlands are areas of floodplain that are deliberately allowed to flood, during wet periods, to reduce flooding elsewhere.
