Recharge — Science definition

Water entering groundwater storage.

Where it is taught

In use

Pumping more water than recharge can lower groundwater storage.

Groundwater, Watersheds & Water Budgets

Questions using recharge

Problem 1

Pumping can change the gradient toward a wellPumping can change the gradient toward a wellPumping draws down a local water levelCompare withdrawal, recharge and nearby measured heads.
Original ideal unconfined pumping section. The lowered line represents drawdown in porous material, not an emptied underground bowl. Actual flow and drawdown depend on geological layers, boundaries and time; arrows are not a contaminant-travel prediction.
Interpret the supplied visual model. What records would help distinguish increased pumping from reduced recharge as a cause of declining well levels?
Answer and explanation

Compare pumping volumes/times, rainfall and recharge estimates, water levels in several wells and local geology. A single falling-level series cannot distinguish all causes.

Trace the arrows toward the pumping well and the lowered blue water-table line. The geometry represents an unconfined teaching model.

Compare pumping volumes/times, rainfall and recharge estimates, water levels in several wells and local geology. A single falling-level series cannot distinguish all causes.

Response criteria

  • Read the labeled quantities, reference frame or objects correctly.
  • Explain the relation between the visual evidence and the mechanism.
  • Keep the drawing’s stated assumptions and limits in the conclusion.

Problem 2

A catchment begins with 300 m³ of stored water. Over one month it receives 100 m³ and loses 70 m³ by outflow/evapotranspiration plus 45 m³ by withdrawal. Find storage change and final storage. Explain why high porosity alone would not guarantee fast recharge.
Answer and explanation

Storage change is 100−70−45 = −15 m³ and final storage is 285 m³. Transmission also depends on connected pathways, permeability, gradients and conditions; porosity alone is a storage fraction.

Combine outputs: 70+45 = 115 m³.

Change is −15 m³; add to initial 300 m³ to get 285 m³.

Distinguish pore-space amount from connected transmission.

Response criteria

  • Use the stated measurements or conditions, with correct units.
  • Connect the result to the physical mechanism or evidence relationship.
  • Identify the assumption, model limit or further evidence requested.

Problem 3

Recharge is 150 units; pumping is 110 and natural outflow is 55. Find storage change.
Answer and explanation

-15 units

150 − 110 − 55 = −15.

Problem 4

Independent chapter check: A catchment begins with 300 m³ of stored water. Over one month it receives 100 m³ and loses 70 m³ by outflow/evapotranspiration plus 45 m³ by withdrawal. Find storage change and final storage. Explain why high porosity alone would not guarantee fast recharge.
Answer and explanation

Storage change is 100−70−45 = −15 m³ and final storage is 285 m³. Transmission also depends on connected pathways, permeability, gradients and conditions; porosity alone is a storage fraction.

Combine outputs: 70+45 = 115 m³.

Change is −15 m³; add to initial 300 m³ to get 285 m³.

Distinguish pore-space amount from connected transmission.

Response criteria

  • Use the stated measurements or conditions, with correct units.
  • Connect the result to the physical mechanism or evidence relationship.
  • Identify the assumption, model limit or further evidence requested.

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