W - 2.1 -> 2.4

Question 1

meteorological drought definition

Answer 1

occurs when LT precip much lower than normal.

• region specific, as atmospheric conditions that result in deficiencies of precipitation are highly variable between climate types

Question 2

agricultural drought definition

Answer 2

insufficient soil moisture to meet the needs of the agriculture in the area.

Question 3

hydrological drought

Answer 3

deficiencies in surface and subsurface water supplies as measured in rivers, lakes + groundwater, etc. originates with a deficiency of precipitation.

Question 4

socio-economic drought

Answer 4

when the water demand for socioeconomic purposes exceeds the water availability.

Question 5

drought in California

Answer 5

• 34% less rainfall in 2013
• 13 consecutive months of drought by 2014
• some rain in Dec 2014 improved this, but needed 5x more to recover
• climate variability accounted for 8-27% of this
• drought = farmers must over extract water - exacerbating the drought

Question 6

meterological causes of drought

Answer 6

ENSO leads to La Nina, which reduces rainfall

Question 7

longer trends

Answer 7

• 5 prev periods in last 500 years where snowpack levels have been equivalent to today

Question 8

Short term precipitation deficit

Answer 8

• south cali consistently below average rain from 13-16
• north has varied, but mostly lower than average

Question 9

hydrological causes

Answer 9

• CA relies on snowfall/ melt for its water supply
• Snowpack has reduced from above average - 136% in 05, to 5% in 15

Question 10

Millenium Drought - Australia

Answer 10

97- 09
- annual rainfall was 12.4% below 20th century mean
- disastrous impact on wheat, wool and meat exports
- prevailing El Nino conditions explain 2/3 of rainfall deficit, but human causes played a role

Question 11

Physical causes

Answer 11

• australia lies on sub tropical ridge - high pressure belt
• el nino events in 02/03 + 06/07, and natural climate change cycles (sunspots) enhance dry conditions
• current warming trend is reducing temp gradient between equator and poles - less energy for mid latitude storms
• 15% drop in rainfall by 2030

Question 12

deforestation

Answer 12

• 90% of basin original veg removed since 1800s
• reduces transpiration/ precipitation
• increases GW consumprion
• added 2 weeks per year onto drought period

Question 13

emissions

Answer 13

• anthropogenic greenhouse gas emission adding to natural variabilities
• climate model evidence most plausible

Question 14

surface water

Answer 14

• 94% of all rainfall evaporates from surface water
• 42% of leftovers are diverted/ pumped for human use through damns and reservoirs

Question 15

groundwater overextraction

Answer 15

• groundwater accounts for 17% of total accessible water resource and 30% of total water use - concentrated in certain areas of basin
• crops (nuts) and herds (cows) increase water demand

Question 16

resulting conflict

Answer 16

• 3.5 million people depend on limited water supply - 32.5k GL a year
• introduction of water cap and Murray-Darling Bain plan overshadowed by illegal over use from farmers above quota
• conflict with environmentalists over wetland water availability
• 16mil Kangaroos have died

Question 17

Mesopotamian marshes

Answer 17

• alluvial fan on Tigris-Euphrates rivers
• habitat for marsh-arabs
• drained from 50s-70s, then eviction of Shia Muslims in 80/90s
• in 03: 10% original size, 500k reduced to 20k
• 16: UNESCO world heritage site
• but turkey still dams the river

Question 18

key physical changes

Answer 18

• dams
• less infiltration
• less percolation
• less GW recharge
• evaporation increases
• transpiration increase
• aquatic + veg die

Question 19

In Iraq

Answer 19

• 250k marsh Arabs part of resistance movement
• lived in south
• Hussein cut off water supply from Tigris-Euphrates
• desertification
• since 03 recovery started

Question 20

why are they not resilient

Answer 20

• soil erosion removes key nutrients, so veg difficult to recover
• new water encourages more soil erosion
• vegetation cant establish itself and begin seres of succession

Question 21

Malaysia Floods 2014

Answer 21

• 200k affected, 21 dead
• NE monsoon heavy rain on 17th Dec
• by 20th dec, most rivers affected
• then road closures + foreign tourists stranded
• 21st dec, heavy rains, Padras river 9.26m above danger level, with heavy overflow

Question 22

flash floods

Answer 22

• intense rainfall, thunderstorm or tropical storm with no warning
• small basins - short lag time
• ground saturated quickly

Question 23

monsoons

Answer 23

• specific heat capacity differences between land and sea
• summer: LP over land, HP over sea, winds blow HP-LP, dragging moisture-laden wind from Indian Ocean

Question 24

prolonged rainfall

Answer 24

• mid latitude depressions queued up over the same place - result of jet stream sinuosity
• UK: two bands of rain
• Ground OK at first, then saturated, surface runoff
• capacity of river fills, then spills over the flood place
• worst in urbanised floodplains

Question 25

snowmelt

Answer 25

• siberia: snowmelt cant infiltrate frozen ground, or gets stuck behind ice dams which then burst
• Himalayas - glacial lake outburst flood
• Iceland - volcanoes melt ice sheets

Question 26

other examples of flooding.

Answer 26

• pakistan, 2010 - 9000m in one week (10x yearly average)
• Mozambique, 2000

Question 27

Pakistan physical causes

Answer 27

• climate change = heat wave = glaciers melt = more rain = exacerbate current conditions
• mainly caused by prolonged rainfall caused by monsoonal depressions ( meter ecological)