[lithocarpus]

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.

[FrustratedMonky]

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.