CIP session 3 & 4: Drought Risk Flashcards
Explain why droughts can occur more or less everywhere across the globe. Use the definition for droughts in you explanation.
Droughts are a sustained period of below-normal water availability. This refers to anomalies in water availability relative to the long-term mean water availability conditions, relevant for each place. As result drought can occur more or less everywhere across the globe. Only in places where water availability is so limited that we cannot quantify the variability we cannot depict droughts and we talk about aridity.
Drought indicators
function of risk
exposure x hazard x vulnerability
Bjerknes’ Ocean-Atmosphere Feedback
Clockwise in air, counterclockwise in ocean
- During El Nino: less upwelling in East leads to warmer East pacific, less evaporation and latent heat leads to cooler west pacific
This leads to a smaller temperature difference and weakened Walker circulation
- During La Nina: More upwellig in East leads to cooler east pacific, more evaporation leads to warmer pacific.
This leads to a bigger temperature difference and a strenghtened walker circulation.
Effect of La Nina
Downflow (drought) over horn of Africa, stronger Indian monsoons
Effect of El Nino
Horn of Africa tends to be wet and West US rain, drought in Indonesia and Australia.
Affects ENSO high latitudes
Southward shift of jet that interferes with normal westerlies. Jet stream brings rainfal to the united states, resulting in more rain in regions like Texas.
Which ENSO state is associated with most drought conditions over continents and name two regions that are strongly affected?
El Nino
Indonesia, Australia, Sahel, South Africa, Amazon
Horn of Africa drought from 2020 to 2022. What is the main source of internal climate variability behind this drought, and how does climate change affect this drought.
La Nina
Climate change intensifies droughts by enhanced evaporation due to a warmer atmosphere
Define Drought Risk and Elements
the probability of harmful consequences or likelihood of losses resulting from interactions between: drought hazard, drought expsure and drought vulnerability.
Drought hazard (and how to meausure)
The collective of prolonged deficiencies in hydro-meteorological variables that may cause loss of life, injury or other health impacts, property damage, social and economic disruption or environmental degradation. Indicators: SPI, SPEI, soil moisture, temperature anomalies etc.
Drought Exposure (and how to measure)
The people, infrastructure, housing, production capacities and other tangible human assets located in drought-prone areas. Indicators: population, land use, livestock, crop types etc.
Drought Vulnerability (and how to measure)
The conditions determined by physical, social, economic and environmental factors or processes which increase the sensitivity of an individual, a community, assets or systems to drought hazard. The degree to which system is susceptible to, or unable to cope with, adverse effects of droughts. Indicators: rural population, refugee population, literacy rate, GDP per capita etc.
water scarcity
Water supply shortage. When the demand outweighs the supply.
Difference between a meteorological and hydrological drought + example of drought indicator
- Meteorological droughts refer to precipitation deficiencies, possibly combined with increased potential evapotranspiration, examples are SPI or SPEI. They are short lived but cover a large area.
- Hydrological droughts refer to negative anomalies in surface and subsurface water systems. They are more local based on local conditions.
