Field notes
Well hydraulics
Specific capacity, drawdown, step tests and aquifer versus well loss: how a water well’s hydraulics are measured, and what a change in them means.
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Well interference: what a neighboring well costs yours
A neighboring well lowers yours by an amount set by its rate, the distance, time, transmissivity and storativity. Every added foot of lift costs…
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Transmissivity from a pumping test: aquifer or well?
Transmissivity comes from the drawdown slope of a constant-rate, recovery or step test. Read with well loss, it shows whether the aquifer or the…
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Step-drawdown test or constant-rate test? What each one tells you about a well
A step test splits drawdown into what the well costs you and what the aquifer costs you. A constant-rate test measures the aquifer. Which…
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How often should a water well be tested? Let the well’s own decline set the schedule
Most districts test wells on a calendar. The right interval comes from how fast each well is losing capacity. A simple rule, a schedule,…
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Is it the pump, the well or the aquifer? How to tell why a well is making less water
Three wells lose 10% of their flow for three different reasons, with three different price tags. Four readings tell them apart before anyone spends…
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Specific capacity: the first number to watch on any water well
Specific capacity (gpm per foot of drawdown) is the earliest honest sign a water well is plugging. How to measure it, compare it fairly…