Methodology
YEIP's two live composite indices, the exact weights and thresholds behind them, and the known data gaps that affect how they should be read.
Groundwater Monitor
A 0–100 composite score per district, combining three weighted components — designed so groundwater, the slowest-moving and most consequential signal, dominates the result. Recomputed weekly as new GRACE-FO and CHIRPS data arrives.
Known gap: aquifer depth data hasn't been sourced for any district yet, so that 15% component currently falls back to a neutral placeholder rather than a real measurement everywhere. The groundwater trend and "years to critical" figures shown on the dashboard are a linear projection from GRACE's relative anomaly, not a measured aquifer reserve.
Drought Monitor
The 3-month Standardized Precipitation Index (SPI-3, McKee et al. 1993): the last 3 months of rainfall, standardized against that same district's own 1981–2010 CHIRPS climatology rather than a flat regional threshold. That's what lets a given SPI value mean the same relative severity in a naturally arid district as in a naturally wet one.
