Drought and desertification Flashcards
what is a drought
“a drought is an extended period of dryness; usually any period of moisture deficiency, that is below normal for a specific area”.
what is a Meteorological drought
is when the precipitation is less than normal
what is Agricultural drought
is when the moisture in the soil no longer meets the needs of a specific crop.
what is Hydrological drought
when surface and subsurface water levels are below normal.
what is Socio-economic drought
when water scarcity starts to affect people.
what is The Palmer Drought Severity Index
Measures how far a region is below normal precipitation, using the variables of precipitation including snowfall, surface air temperature, soil moisture, evapotranspiration, and runoff.
what do negative and positive numbers show on the PDSI
Negative PDSI numbers indicate drought and positive numbers indicate moisture.
what are the four classifications of droughts using the PDSI
- Mild drought -1 to - 1.99 PDSI
- Moderate drought -2** to -2.99 PDSI
- Severe drought -3** to -3.99 PDSI
- Extreme drought- -4 PDSI or less
2 good things about the palmer drought severity index
The PDSI is the first comprehensive drought index and it is also standardised
3 pros of the Plamer drought severity index
- First comprehensive drought index
- A ‘standardized’ drought index,
- Effective in determining long‐term drought, especially over low and middle latitudes.
why is it good that the drought severity index is standardised
makes easier comparison at different locations/times
what are the two cons of the drought severity index?
- it may lag emerging droughts by several months
- doesn’t account for delayed runoff from snow/ice.
what is the global drought monitor
The global drought monitor takes into account various measures of droughts to calculate the return interval for various severities of droughts.
what are 6 economic impacts of droughts
droughts can lead to loss of livestock production loss of crop production increased energy demand loss of tourism income loss for farmers decreased land prices etc.
3 environmental impacts of droughts
droughts damage animal species, plant species, wetlands.
impact air quality due to dust.
Increased stress on endangered species or even extinction
3 social impacts from droughts
food shortages
mental and physical stress
migration,
increased conflict,
where had the biggest drought, what country, what year how many people died
China has the greatest number of drought fatalities, with 3 million people dying in 1928.
how many people died in sudan, what year.
Recently, 150,000 people died in Sudan in 1985.
years that are generally warmer have what
Years with higher temperatures generally have higher overall mortality rates.
what is the response to droughts in the global south, what is good about it what is bad about it?
there is often a call for international aid, partly in the form of food rations. This is crucial during times of famine but can flood local markets and put farmers out of business.
what response is common to droughts in the global north
governments put water-saving measures into place such as hosepipe bans.
what are some of the effects of droughts in the global north,
Droughts can cause ground subsistence which can damage building foundations and cause railways to buckle.
what is desertification
the degradation of a semi-arid region caused by natural or human factors resulting in more extreme arid conditions.
what is normally associated with droughts
It’s often associated with droughts as droughts can accelerate the degradation of non-desert land so that it becomes a desert.
