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Earth Systems Science · Module 5 · Station Lab

The Overdraft Simulator

HS-ESS3-3 HS-ESS3-4 HS-ESS3-6 4 stations ~45 minutes

An aquifer pumped just past its recharge rate looks fine for twenty years, then does not.

Phase 0 · The phenomenon

Twenty good years

Spring flow in the valley after pumping begins at 110% of recharge (model run). The decline slows down year after year, then the spring stops.

A line chart of spring flow against years. It starts at 100% of natural flow when pumping begins, falls steadily but more and more slowly over two decades, and reaches zero at about year 24, staying dry afterward.

A valley town drills wells into the aquifer that feeds its spring-fed creek. Engineers add up the rainfall that soaks in each year and set pumping just 10% above that figure. The wells keep producing. The water table falls, but slowly.

For about twenty years the wells keep producing and the creek keeps running, a little lower each summer. Then the spring that has run for thousands of years stops — and with it go the creek, its fish and the cottonwoods along its banks.

Nobody pumped faster that year. In this lab you will run the aquifer's water budget and find out why the failure came so late, and so suddenly.

Essential question

Why can an aquifer pumped only slightly faster than it refills look fine for decades — and then fail?

What this lab works toward

  • HS-ESS3-3Build a computer simulation linking how we manage natural resources to the sustainability of people and biodiversity.
  • HS-ESS3-4Evaluate or improve a technology that reduces human impact on natural systems.
  • HS-ESS3-6Use a computer model to show how Earth systems are linked and how human activity is changing those links.

Plain-English summaries. The course maps these performance expectations to this lab; the official wording is published at nextgenscience.org.

The stations

  1. Water BudgetIf pumping stays below recharge, is the aquifer's spring safe?
  2. Time LagWhat sets how many years an over-pumped aquifer looks fine?
  3. Fix BenchWhich combination of less pumping and added recharge brings the spring back?
  4. Drought YearsHow do droughts — and pumping more during them — change the outcome?

Each station runs the same loop: predict before you see any data, investigate the model and record runs, reveal what the measurements show, then explain the gap between your prediction and the result. A claim-evidence-reasoning checkpoint and an exit ticket close the lab.