eq2 simple defini Flashcards
define drought
a prolonged period of time where rainfall hasnt been present.
what are the 4 types of drought
agricultural
meterological
hydrological
socio-economic
what is a hydrological drought
occurs when there is deficiencies in surface and subsurface water supplies.
what is meteorological drought
when long term precipitation is lower than normal
what is a argicultural drought
when there is not enough soil moisture to allow enough crops to grow
what is socio economic drought
the water demands fro social and economic purposes exceed water avaiblity
what are the 2 phases of ENSO
El nino
la nina
what is ENSO
EL NINO SOUTHERN OSCILLATION
Lareg scale climate pattern including el nino and la nina
what is el nino
naturally occuring large mass of very warm water in equatorial pacific ocean
trade winds weaken thus warm water moves to the middle of the sea, this causes high amounts of rainfall in the sea and sinking air to the East of Australia which will then receive dry conditions and drought
what is la nina
-when normal conditions are strenthened.
Here, trade winds are stronger which pushes warm water closer to Australia, here the increased heat causes air to rise which forms clouds and rainfall in Australia, sinking air occurs in South America causing drought/ dry conditions
what 5 factors icrease droughts- human
. abstraction
.changing land use
.deforestation
overgrazing
how does deforestation n lead to droughts
reduces vegetation cover- reduces evaportaranspiration rates- reduces atmospheric moisture and precipation
what is the itcz
is a band of low pressure around the Earth which generally lies near to the equator, it can move
what are the 3 physical causes of drought
The Intertropical Convergence Zone
Mid Latitude Anticyclone Blocking
El Niño Southern Oscillation Cycles (ENSO)
what are mid latitude anticyclone blocking and how do they cause drought
its a high pressure system so doesnt bring rain, prevents movement from itcz
what is a wetland
a land area saturated with water, either permanently or seasonally, including marshes, swamps and fens
give an example of a large and small wetland
Small-minsmere suffock
Large-Florida
what did the environment agency find about drought on wetland ecosystems
water and soil
reduction in water- areas of water dry up- resulting in progressive loss of habitat.
soil dry ups meaning soil ersion occurs and reduces ability to store water in times of flood.
organic soils may oxidise- releases carbon in atmosphere.
how do droughts negativelty affect the wet land ecosystem
can alter communities by elimintaion some species and creating gaps in the food chain
how does forest die-off cause drought?
deforestation=> less vegetation and thus less transpiration back into the atmosphere=> less humidity and recycling of water
what six factors are forest ecosystems highly valued for
.water storgae
.regulation of hydrological processes
.timber production
.wildlife habitat
.carbon sequestration
.recreational opportunities
what have researchers revealed about forests
average of two to four years to recover and resume normal growth rates- following a period of drought.
what has long term forest loss cuased due to droughts (3)
foliage loss
impairing growth
increased accumulation of pests
give an example of a forest ecosystem affected by severe drought
Pinion pines in the four corners region of the south west USA
What did drought do to the Pinion pines
in some areas more than 90% of the pinions died resulting in major ecosystem changes
what did the Global Footprint Network measure how much forests sequester per year
the GFN calculated that forests store an average of 0.73 tonnes of carbon per hectare per year, which is important for climate change
what is a flashflood
floods that occur very quickly without warning- may be caused by intense heavy rainfall.
name a place where flashfloods where evident and list the economic and social factors
saradinia
atleast 18 deaths
1.4b in damage
what are the meterlogical causes of flooding
monsoon and flash flood
what is a monsoon
a seasonal change in the direction of the prevailing windsof a region, causing wet and dry seasons in many sub tropical areas
where do monsoons occur and when is it peak
india and south east asia- peak in april and septemeber
what can human impacts of flooding being linked to (3)
population increase
urbanization
deforestation
how do urban drainage systems contribute to flooding
reduces the natural capacity of the floodplain
causing land to shrink as it dries out, getting lower and thus an even greater susceptibility to flooding
how does the population increase the risk of flooding
population pressure causes vegetation removal for agricultural development and living spaces- these land changes increase run off
how does the deforestation increase the risk of flooding
reduces interception and evapotranspiration- increasing surface runoff.
ensures precipitation reaches river channels faster-flashy hydrogrphs
how does deforestation affect the soil
expose to greater erosion, increasing river sediment load-reduces the capacity of river to carry water- increases flooding
how does the urbanization increase the risk of flooding
the expansion of impermeable surfaces (roads)increases surface runoff.
what does the IPCC predict about climate change and the hydrological cycle
predicts considerable changes to the global hydrological cycle as a result of increasing greenhouse gas concentrations
list some potential impacts of climate change on the UK water cycle by 2050
rainfall events will be much more intense (heavy downpour)
-more flooding expected
-Coldwater species will decline, this increases invasive species
-Estuaries at increasing risks from floods
-sea level will rise between 0.4m and 1m by 2100
-urban areas will see more flash flooding
-higher demand for water
give an overview on how climate change will affect the global hydrological cycle
warmer temperatures will increase the atmospheres ability to hold water vapour, thus rain will be more intense
change in storm patterns
as temperature rises, decrease in snow,permaforst
warmer temperatures will cause earlier snow melt, this means less water available for human use
more flooding
increased incidence of drought
what is the IPCC
The Intergovernmental Panel on Climate Change (IPCC) is the international body for assessing the science related to climate change
what are 3 reasons why predicting the impact of climate change is difficult
-climate dynamics- the way the atmosphere, ocean, terrestrial, cryosphere and biospheres interact is only partially understood
- the complexity of teh global climate system means its difficult to distinguish between the impacts of oscillation such as ENSO (El Nino Southern Oscillation) and climate warming
-Global records are very incomplete- there is no reliable evidence on trends on climate change in many parts of the world making firm predictions hard
-variables and uncertainty
what does the IPCC consistently predict about climate change and the water cycle
-precipitation will become more variable
-increased risk of droughts and flooding
-IPCC represent serious concerns over the security of water supplies in the future
