Groundwater flows to well

Question 1

maximum rate of pumpage that can be allowed while ensuring that water-level declines are kept with acceptable limits.

Answer 1

Groundwater yield

Question 2

maximum pumping rate that can be supplied by a well without lowering the water level in the well below the pump intake

Answer 2

Well yield

Question 3

maximum rate of withdrawal that can be sustained by an aquifer without causing an unacceptable decline in the hydraulic head in the aquifer

Answer 3

Aquifer yield

Question 4

maximum rate of withdrawal that can be sustained by the complete hydrogeologic system in a groundwater basin without causing unacceptable declines in hydraulic head in the system or causing unacceptable changes to any other component of the hydrologic cycle in the basin

Answer 4

Basin yield

Question 5

WHAT CONTROLS GROUNDWATER FLOW?:

Answer 5

continuity equation

Question 6

Continuity Equation

Answer 6

Inflow – Outflow = Change in volume

Question 7

• Darcy flow in
• Recharge
• Exchange with SW

Answer 7

Inflow

Question 8

• Darcy flow out
• Evapotranspiration
• Exchange with SW

Answer 8

Outflow

Question 9

• Change in saturation (Variably saturated)
• Change in water level (Unconfined)
• Compressibility of the aquifer (Confined)

Answer 9

Change in volume

Question 10

Relates to compressibility of materials, water and solid rock/grains

Answer 10

Specific Storage

Question 11

What properties affect drawdown in an unconfined aquifer?

Answer 11

• Storativity
• Horizontal conductivity
• Vertical conductivity
• Specific yield

Question 12

Phase 1 of the Neuman Solution

Answer 12

Drawdown is controlled by the Ss of the saturated part of the aquifer

Question 13

Phase 2 of the Neuman Solution

Answer 13

Drawdown is controlled by the vertical conductivity of the aquifer

Question 14

Phase 3 of the Neuman Solution

Answer 14

Drawdown is controlled by the specific yield of the aquifer

Question 15

Assumptions for the Neuman’s Solution

Answer 15

1 Aquifer is unconfined
2. The vadose zone has no influence on the drawdown
3. Water initially pumped comes from the instantaneous release of water from elastic
storage.
4. Eventually water comes from storage due to gravity drainage of interconnected pores.
5. The drawdown is negligible compared with the saturated aquifer thickness.
6. The specific yield is at least 10 times the elastic storativity.
7. The aquifer may be—but does not have to be—anisotropic with the radial hydraulic conductivity different than the vertical hydraulic conductivity

Question 16

-Rate of recovery dependent on

Answer 16

well geometry and Hydraulic conductivity

Question 17

Rate of head fall in the piezometer =

Answer 17

Radial Darcy flow out of the piezometer

Question 18

Slug tests are generally performed in what

Answer 18

piezometers

Question 19

2 kinds of slug tests

Answer 19

-Falling Head Slug Test
-Rising Head Slug Test

Question 20

Limitations of Slug test

Answer 20

• Much smaller area of influence than a pump test:
  o On the scale of meters
  o Very local properties
  o Important for contaminant movement
• Different materials
  o Low K – won’t recover fast enough
  o High K – will recover too fast