Comment by 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.