What is a drought? When it rains, does that mean the drought is over?
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The official definition of a drought is “a period of abnormally dry weather sufficiently prolonged for the lack of water to cause serious hydrologic imbalance in the affected area.”
So firstly it must be abnormal – as in it doesn’t rain as much as it normally does somewhere. If it rarely rains (e.g. a desert) and it still doesn’t rain it doesn’t count as a drought
And the second part is that it must last long enough and be dry enough for there to be a “hydrologic imbalance” which means it must be dry enough to actually impact the environment
This can happen in a few different ways –
Probably the most commonly thought about one is agricultural – when crops start to struggle to grow or die off
Then there is socio-economical which is where the water supply impacts the human population – either with increased cost to industry or a shortage of drinking water supply which can result in water restrictions (or in severe cases places running out of water completely)
There are also environmental droughts which is where the drought starts to impact the natural environment
Most droughts will be a combination of all three depending on where the occur and how severe they are
When it rains it certainly helps to end the drought (commonly referred to as breaking the drought) but it does not necessarily mean it’s over – a drought is not considered over until the “hydrologic imbalance” has been corrected. Which one period of rain might not be enough to achieve.
Or in severe, and cases (like we may see with climate change) until the dry weather is persistent enough to be considered the new normal (note that to be considered persistent enough it would have to be a drought for a very long period of time, probably a generation or two)
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