Droughts and heatwaves

4 important questions on Droughts and heatwaves

What could cause water scarcity in Iceland?

  • Small villages in Iceland rely on drinking water from their direct area and are not connected to a DW network.
  • Quality issues and hence purification obstacles

How does KNMI measure the drought index?

Precipitation deficit: P-ETpotential (from 1st of April each year). This is based on the Makkink method.

NL is changing towards SPI, not necessarily good step forward, but internationally wider used.

Each country might measure this differently based on their climate and socioeconomic needs.

Explain several drought indices that are often used (internationally, e.g. EU):

Percent of Normal (pN):
pN = Pact/Pnorm*100

Agricultural, meteorological, ...


Standardized indices (SPI, SGI, SPEI, SRI): drought as st dev from normal, thus taking into account the spread.

Long term precip record (monthly data), fit a stat model to this precip TS bc it is not yet normally distributed. Typically a Gamma distribution is used (check in case min 37).
  • Higher grades + faster learning
  • Never study anything twice
  • 100% sure, 100% understanding
Discover Study Smart

What do we know about drought changes on both EU and global scale?

Trend towards dry:
Basins that are not heavily influenced by humans show a negative trend in streamflow across most of EU. It may be due to increased ET.  

Trend towards increased ET on the long term, found by Teuling (global scale). Previous paper found decreasing ET, but Teuling found this trend was ENSO influenced and the scale was too small.

The question on the page originate from the summary of the following study material:

  • A unique study and practice tool
  • Never study anything twice again
  • Get the grades you hope for
  • 100% sure, 100% understanding
Remember faster, study better. Scientifically proven.
Trustpilot Logo