An Aquifer-Safe Draw Bound for a Village Well Field: Why Recharge, Not Drawdown, Sets the Rate

This paper derives the largest sustained pumping rate for a three-well village field at 150 m spacing in an aquifer with transmissivity 200 m²/day and storage coefficient 0.08, over a 180-day dry season with an allowable drawdown of 8.0 m. Cooper–Jacob superposition gives a drawdown-limited rate of 796.9 m³/day per well — and a spacing–rate table in which widening spacing from 75 m to 300 m raises that limit only from 718.0 to 895.3 m³/day. The water balance is far stricter: at 100 mm/year recharge over the stated capture area the sustainable rate is only 16.44 m³/day per well, and at zero recharge every cubic metre pumped is mined from storage. The usable rule is therefore two-gated: take the smaller of the drawdown rate and the recharge rate, and print the no-recharge case as mining, not as supply. SIMULATED, NOT MEASURED.