What is a drought? When it rains, does that mean the drought is over?

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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)

Drought is the name given to a weather effect that is significant in that it isn’t typical for the climate

Climate means long-lasting dependable weather patterns that are usually stable trends for a specific area

Because the natural plants (or the planted crops) are usually suited and adapted to the climate that they exist in, a sudden weather event can kill them by changing the living conditions temporarily – but even if the change is only temporary, the dead (or very sick) plants can’t recover, and that can result in problems to the whole ecosystem that sits on the pyramid that exists on top of that producer

Rain doesn’t always end a drought, the rain needs to be back at a level that is either back to typical climate pattern, or at a level to sustain plant life to a recovery, it depends on the definitions you want to use, farmers and scientists will care about different things

When there is a drought many plants die, native, farmer planted. When it does rain the drought is not over. You need a long term period of consistant rain rather than a one off rain event. Things like introduced weeds have adapted to drought conditions so can be the first plants to appear. Not good for anyone.

One rainfall won’t end a drought. Under normal conditions in my home area in Central Europe, during summer it will surely be dry, but if you are digging, there would be a certain amount of humidity being left in the soil deeper down.

When there is a drought, even the humidity deeper down is lost. And even if it is raining then, only the topmost layers of soil are getting wet before the humidity evaporates again. But to have a healthy plant life and enough crops there needs to be enough humidity in the deeper layers. And this is missing more often in the past years.

a drought means that less water falls to sustain life over the year.

It effects the natural vegetation, animal life and even fish in the ocean.

A single rain is welcome but it doesn’t catch the ecosystem up with where it should be. AND with a serious dry spell, much of that water is likely to just run off and not get absorbed into the ground.

(if you let a container plant get toooo dry, the soil will pull away from the pot so when you do water it, most of it runs down the gap on the sides and out the bottom, you have to put the pot in a tub and let it soak up from the bottom till it loosens and swells again)