Comment by Jensson
1 month ago
Drought doesn't mean "abnormally dry" though, it means lack of rain resulting in water shortage. And California has had a lot of water shortages.
1 month ago
Drought doesn't mean "abnormally dry" though, it means lack of rain resulting in water shortage. And California has had a lot of water shortages.
It's not quite as simple as that though - in most places, especially California, water shortages are not a simple natural imbalance between the amount of rain that falls and how much flows out in rivers and streams.
If demand is far higher than supply due to overuse by industry that's definitely a water shortage - there isn't enough of it, and something is probably suffering as a result. I don't think that's a useful definition of drought though. If someone builds a massive factory consuming 100s of millions of gallons of water per day that's definitely going to cause a problem but I'm not sure it's reasonable to say that there's suddenly a drought.
I think the definition of drought is instead current rainfall compared to historical average - which then leads to the question of if the change is just that rainfall has now been low for so long the historical average has changed, or if rainfall has actually improved. I don't think the article addressed this, but I only skimmed it so maybe I missed it.
> If someone builds a massive factory consuming 100s of millions of gallons of water per day that's definitely going to cause a problem
Lots of factories in Washington, seemingly no problem.
Are you implying 800 miles worth of latitude, along with North Pacific weather in general, is irrelevant?
1 reply →
I think what he is getting at is : deserts are already dry, what makes a drought in the desert?
It isn't just, a lot of people moved to the desert, so now there is a drought because there isn't enough water.
I don't have reference, but I think there is some definition around change from average.
Drought it something like X months with Y% less precipitation than last 5 year average. or some such calculation.
If you have a fertile abundant landscape covered in old growth forests and marshes, and then cut all the forests, put roads everywhere, and plough up the marshes for farming, the landscape then holds a lot less water and the weather becomes less stable, which can exacerbate natural fluctuations in rainfall and temperature making droughts more common and more severe.
This is effectively what happened to large parts of the middle east that were once fertile and lush. It's a trend all over the world really.
There are many ways humans can work the opposite direction to increase the ability of the land to stabilize the weather and increase hydrological robustness to mitigate droughts, e.g. regenerative agriculture or projects in asia and africa to green the desert, I don't know enough about them but it's a good idea and I hope it's executed well.
All I'm saying is that people or no people, wet or dry, there is an actual calculation and a drought scale. The conversation seems to be wanting to place 'blame', but you can have droughts anywhere, under a lot of conditions (like people moved in) for lots of reasons.
I looked it up
Calculating drought involves comparing current conditions (precipitation, temperature, soil moisture, water levels) to historical norms using standardized indices like the Palmer Drought Index (PDSI) or the Standardized Precipitation Index (SPI), which measure water supply/demand imbalances over short or long periods to assign severity levels (e.g., D0 Abnormally Dry to D4 Exceptional Drought).
A common method uses indices that turn negative as drought intensifies, with thresholds indicating different drought stages, often combined with expert analysis for the official U.S. Drought Monitor.
Common Drought Indices
Palmer Drought Severity Index (PDSI):
Uses precipitation, temperature, and soil moisture. Calculates water supply and demand. Values: Below -0.5 indicates drought; below -2.0 is moderate.
Standardized Precipitation Index (SPI):
Focuses on precipitation deficits at various timescales (e.g., 1, 3, 6 months). Classifies drought: e.g., -1.0 to -1.49 is Moderate, -2.0 or less is Extreme.
Yes exactly, saudi arabia doesn't have an ideal amount of rainfall for providing water to people and growing crops, but nobody say it's in a "drought".
It would be nice if it rained more in california, but we can't base definitions on what we'd ideally like to happen