Impact of Urbanisation

Question 1

How does urbanisation impact the water cycle ?

Answer 1

Summarise how urbanisation has impacted the water cycle
It interrupts and rearranges the inputs,storage and transfer water
There is a link between urbanisation and problems of declining water resources, ^ pollution and ^ flood risk.

Vegetated soils are replaced with impermeable surfaces which cover 20% of postwar urban areas but in a city centres can be as high as 90%
Suburban detached housing it can be 5%

Question 2

Risk factors human

Answer 2

• deforestation
• urbanisation
• agriculture
• ice melt

Question 3

risk of physical factors

Answer 3

• Drainage density
• Precipitation
• Rock type
• Relief of drainage basin

Question 4

what is a storm hydrograph?

Answer 4

shows variation in a river’s discharge (or channel flow) within a short period of time

Main purpose = record how a river responds to precipitation

Question 5

How does vegetation impact flood hydrograph shape?

Answer 5

If you have more
* More trees intercept the rain
* Evapotranspiration ^ → less water reaches the river
* Water used by vegetation → less water in river

Question 6

What are the scales of vegetation on shape of hydrograph?

Answer 6

• Broad Leaved vegetation intercepts more
• Winter winter less interception takes place as loss of leaves

Question 7

vegetaiton -graph effects

Answer 7

• Longer lag time as more time for water to reach the river
• Lower peak discharge → as less water within the river

Question 8

Shape of basin impact on flood hydrograph

Answer 8

• Smaller drainage basin respond more quickly to rainfall conditions
• Circular basins respond more quickly than linear basins → river responds much more quickly to a flood

Question 9

How does steepness of profile affect flood hydrograph shape?

Answer 9

• Steeper slopes generate more overland flow → more water immediately after a flood event
• Gentler profile → takes longer to reach river / water may be lost causing lower discharge

Question 10

steepness of profile -graph effects

Answer 10

• Shorter lag times
• Higher peak discharge

Question 11

Drainage density affect on hydrograph shape

Answer 11

Basins with high drainage density such as urban basins with network of sewers and drains are quick to respond

• Networks with low drainage density have a low drainage density → longer lag time