The Earth is blue for its oceans but green for its groundwater. We use wells to extract water from the ground. In this course we address questions such as: how well tests tell us if an aquifer can provide enough water? how can we use wells to dewater construction sites?
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Groundwater is the water beneath the ground surface. It is a vast freshwater reservoir often overlooked because invisible, yet 1000 times greater than all lakes and rivers.
The Earth is blue for its oceans, but green for the freshwater under our feet. Half of the world’s population rely on groundwater for drinking and almost half of the irrigated land now depends on groundwater, a ten-fold increase in the past 50 years. In order to use the water from the ground, we first have to extract it! This course introduces wells hydraulics. Wells are used to provide groundwater for domestic, agricultural or industrial uses. Wells are also used in applications to control groundwater flow and contamination. Pump and treat systems are designed to extract contaminated water before it can be treated. The treated water is released to the environment, sometimes using recharge wells that can replenish aquifers. Wells can also control salt intrusions in coastal environments or the water table level at a construction site.
This course addresses questions such as:
- How exactly do we extract groundwater?
- How do we know if an aquifer can provide enough water?
- How do we model underground flow to wells?
- How can we use wells to remove water from construction sites or water-logged fields?
This wells hydraulics course starts with a description of steady flow to wells. We introduce the notion of radial coordinates and steady flow to wells in confined and unconfined aquifers. We also introduce finite difference methods to model flow to wells. We introduce transient flows in confined, semiconfined and unconfined aquifers. We use graphic methods and semi-automated methods to calculate aquifer properties from well tests. We also introduce slug tests and their analysis.
After the well and slug tests, we introduce well fields and issues of dewatering. We review the superposition principle and problems of domain boundaries before focusing on dewatering examples. We continue to explore the topic of well fields in the context of extraction and injection wells, with an example of pump and treat design and an in-situ remediation design. We also show an example of a well model in MODFLOW.
What you'll learn
- Describe the steady-state flow to wells in confined and unconfined aquifers
- Explain the correspondence between linear and radial coordinates
- Derive the flow equations for steady flow to wells
- Build simple aquifer models
- Apply the flow equations to estimate aquifer parameters
- Design wells for steady water supply
- Describe the unsteady flow to wells in confined, semi-confined and unconfined aquifers
- Explain what well functions are
- Use graphical methods to calculate transmissivity
- Compare the (transient) flow behavior in (semi)confined and unconfined aquifers
- Explain slug tests
- Contrast slug tests and well tests
- Choose the appropriate analysis to calculate aquifer properties from slug tests
- Model aquifers and wells
- Apply analytical methods to steady state flows
- Use finite difference methods to model aquifers and wells
- Use computer models to automate calculations
- Relate mathematical models to numerical models such as MODFLOW
- Explain how well fields work
- Apply flow equations for multiple wells
- Explain how boundaries can be modeled with multiple (imaginary) wells
- Plan dewatering systems
- Interpret pump and treat systems from a hydraulics perspective
Syllabus
Week 1: Steady Flow to well
We start with the description of radial coordinates and steady flow to wellsin confined and unconfined aquifers. We also introduce finite difference methods.
Steady Flow to Well
Radial Coordinates
Steady Flow to Confined Well
Finite Difference
Week 2: Transient Confined and Semi-Confined Flows
We describe transient flows in confined and semiconfined aquifers. We use graphic methods and semi-automated methods to calculate aquifer properties from well tests.
Transient Confined Flow
Transient Confined
Transient Confined: Graphic Method
Transient Confined: Straight Line
Transient Leaky Confined
Week 3: Transient Unconfined Flows
We continue to describe well tests in unconfined aquifers to calculate unconfined aquifer properties. We also introduce slug tests and their analysis.
Transient Unconfined
Slug Tests:
Cooper Method
Hvorslev Method
Bouwer and Rice
Week 4: Well Fields and Dewatering
We start by reviewing the superposition principle and review the problem of domain boundaries. We then focus on dewatering examples.
Wells Fields
Superposition Principle
Boundaries
Dewatering
Week 5: Pump and treat / Capture Zones and MODFLOW models
We continue to explore the topic of well fields in the context of extraction and injection wells. We show an example of pump and treat design and an in-situ remediation design. We also show an example of a well model in MODFLOW.
Pump and Treat/ Capture Zones
MODFLOW
