I applied five mathematical models to USGS aquifer data. Four of six major US systems are in overdraft. Here are the overshoot ratios

I collected depletion rates, withdrawal volumes, and recharge data from USGS, the Edwards Aquifer Authority, Kansas Geological Survey, and California DWR for six major US aquifer systems. Then I applied five standard models (carrying capacity, Lotka-Volterra competition, Bass diffusion, critical slowing down, Day Zero projection) to answer two questions: how far past sustainable yield is each system and what happens when multiple users compete for the same declining resource.

The overshoot ratios (annual withdrawals divided by annual recharge):

- Ogallala: 4-11x. Natural recharge cycle: ~6,000 years. ~9% of total storage depleted since the 1950s

- Edwards (Texas): ~8.6x during current drought. J-17 index well at 628.2 ft (Feb 13, 2026). Springs intermittent at 620 ft, cease at 618 ft. That is 8.2 feet of buffer

- Central Valley (California): ~1.2x. Sounds modest until you note 28 feet of irreversible subsidence since the 1920s, ongoing at 1-2 ft/yr

- Sparta: ~1.25x. 200+ ft local declines since 1920s

- Memphis Sand: ~1.0x. At limit. Primary risk is contamination, not volume (6 confirmed breaches in protective clay layer)

- Floridan: ~0.35x. Below capacity, but saltwater intrusion advancing 200-300 ft/yr

The Lotka-Volterra competition model shows agriculture at 70-87% of withdrawals is the structural driver of overdraft in every system analyzed. Data centers are 1-5%. Both facts are true simultaneously.

I also applied Bass diffusion to drought emergency declarations (61 events, 45 jurisdictions). The q/p ratio came out at 4,386, meaning declarations are overwhelmingly imitation-driven. Climate creates the physical precondition; politics determines timing. 16 new jurisdictions declared in Q1 2026 after 29 in all of 2025

I am not a hydrologist. The models are standard (carrying capacity is textbook, Lotka-Volterra dates to 1925, Bass to 1969). The work is applying them together to publicly available data and presenting results for a non-specialist audience. Full methodology, sources, and limitations are in the writeup.

Full article with all source links and model limitations: https://alexnik2.substack.com/p/the-physical-layer-02-the-overshoot?r=604nis

Corrections welcome. If you work in hydrology and see errors in the methodology or data, I want to know