Water

Question 1

Given an example of a river with a simple regime. What is the main influencing factor?

Answer 1

The river Yensei in Siberia (or Arve of Chamonix) which experiences a period of high discharge during the spring and summer due to snowmelt

Question 2

Give an example of a river with a complex regime. What are the main influencing factors?

Answer 2

The river Mekong has a large catchment area and therefore experiences different climates across its basin as well as varying terrain and vegetation.
Close to its source in the Tibetan Plateau there are large mountains causing orographic rain whilst its mouth in in the tropics experiences conventional rainfall and the Asian Monsoon

Question 3

What caused the 2018 UK drought?

Answer 3

Mid-latitude blocking anticyclone

Question 4

What were the physical and human causes of drought in Brazil? What impact did this have?

Answer 4

PHYSICAL:
ENSO cycles (normal conditions and La Niña)
blocking anticyclones and high pressure systems

HUMAN:

• deforestation which lead to less evapotranspiration making the rainforest less resilient and casuing meteorological drought. Lead to the albedo effect
• over abstraction of groundwater lead to hydrological drought and therefore agricultural drought and then famine. Only 30% of wells were legal. 4 million people in the state of São Paulo were rationed on water.

Question 5

What were the physical and human causes of drought in the Sahel? What impact did this have?

Answer 5

PHYSICAL:
Strong teleconnection with El Niño
Blocking high pressure from Hadley cells along the STR prevented moisture from reaching the Sahel (Meteorological drought all the way to famine as crops died)

HUMAN:
- high poverty and low human development as well as extreme population growth mean that there is more pressure for food and water this means that already drylands are being over cultivated and over grazed causing desertification, especially in theNorth

Question 6

What were the physical and human causes of the millennium drought in SE Australia? What impact did this have?

Answer 6

PHYSICAL:
El Niño events in 2002/03 caused 2/3 of rainfall deficit in eastern AUS
High pressure systems along the STR blocked rain and storm pathways

HUMAN:

• changes within the Hadley Cells and STR can be attributed to anthropogenic climate change as global surface temps increased which intensifies the high pressure systems across the STR
• this also decreased the temperature gradient between the poles and the equator leading to a decrease in polar fronts along the jet stream bringing less rain

Question 7

How did the Aswan Dam influence the Nile drainage basin?

Answer 7

• Surface area of the reservoir is larger than the usual river leading to increased evaporation leading to a 20-30% reduction in discharge downstream
• dam regulates river discharge which evens out the natural yearly fluctuations leading to more localised drought during the ‘rainy’ season as water didn’t flow properly. Also impacts migratory birds

Question 8

What impact did the Soviet Unions over abstraction of the Aral Sea have on the drainage basin and people?

Answer 8

Water table was lowered leading to a decrease in groundwater flow
It was used to irrigate cotton farms but when it dried up it led to salt crystallisation and pesticides drying up. Now when the wind blows it takes these chemicals and salts to nearby towns causing respiration issues

Question 9

What impacts does drought have on forest ecosystem functioning (California Oregon pine forests)?

Answer 9

Dries out the wood leading to vascular damage and growth stunting which reduces its timber value
Also reduces its efficiency as a carbon sink and therefore its atmospheric function
Even more extreme during forest fires of August and September 2020

Question 10

What impact did drought have on Minsmere (Suffolk) wetlands ecosystem functioning?

Answer 10

Less river flow into wetlands meaning plant species dry up which means they cannot clean the water for streams and human use leading to salt crystallisation and eutrophication also more vulnerable to erosion
Also loss of aquatic bird habitats

Question 11

What were the physical and human causes of flooding in Cumbria 2015? What impact did this have?

Answer 11

PHYSICAL:
- jetstream brought depressions from across the Atlantic e.g. storm Desmond
- mild mountainous terrain in the Cumbrian Fells lead to orographic rain
HUMAN:
- urbanisation increases impermeable surfaces as well as deforestation and land use change to arable farmland decreases the rate of interception
- river channelisation lead to increased peak discharge but further downstream the river could not cope e.g. confluence at Carlisle

IMPACTS:
- 5200 homes flooded 
-£450 mil in damages
- closed the United Biscuit Factory for several weeks which is the cities largest employer
-

Question 12

What human influences caused flooding in Haiti?

Answer 12

• deforestation of 98% of its forests

Question 13

What caused flooding of the Mississippi River?

Answer 13

River channelisation and artificial levees constructed the water and put pressure on the levees until they burst