Boundaries and Superposition

1 / 21

# Boundaries and Superposition - PowerPoint PPT Presentation

Boundaries and Superposition. Groundwater Hydraulics Daene C. McKinney. Introduction. Review Continuity in Aquifers Steady flow to a well in confined aquifer Superposition Two Wells in an Aquifer Image Well for an Impermeable Boundary for a Constant Head Boundary

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

## Boundaries and Superposition

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

### Boundaries and Superposition

Groundwater Hydraulics

Daene C. McKinney

Introduction
• Review
• Continuity in Aquifers
• Steady flow to a well in confined aquifer
• Superposition
• Two Wells in an Aquifer
• Image Well
• for an Impermeable Boundary
• for a Constant Head Boundary
• Multiple Wells in an Aquifer
Continuity in Aquifers
• Confined aquifer
• Unconfined aquifer
• Linear equations
• If h1 and h2 both satisfy a linear equation
• Then another solution is

h3 = Ah1 + Bh2

• where A and B are constants

(For unconfined aquifer, everything is in terms of h2)

Steady Flow to a Well in a Confined Aquifer

Q

Ground surface

Pre-pumping

Pumping well

Drawdown curve

Observation wells

Confining Layer

h0

r1

hw

h2

b

h1

Q

Confined aquifer

r2

Bedrock

2rw

Point of interest (x,y)

Well at = (xw,yw)

Steady Flow to a Well in an Unconfined Aquifer

Q

Ground surface

Pre-pumping

Water level

Pumping well

Water Table

Observation wells

h0

r1

hw

h2

h1

Q

Unconfined aquifer

r2

Bedrock

2rw

Example

Q = 2x10-2 m3/s, T = 5x10-3 m2/s, Ho = 25 m, rw = 0.25 m

y

x

600 m

Well 1

pumping alone

Well 2

pumping alone

Both wells

pumping together

Example
• How much does the pumping in well 2 affect the head in well 1?
• With both wells pumping
• With only Well 1 pumping
• Difference = 1.54 m

x

Summary
• Review
• Continuity in Aquifers
• Steady flow to a well in confined aquifer
• Superposition
• Two Wells in an Aquifer
• Image Well
• for an Impermeable Boundary
• for a Constant Head Boundary
• Multiple Wells in an Aquifer