Geology Chapter 9 Flashcards

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Questions and Answers

What is an aquifer?

An aquifer is a permeable layer of rock and sediment that contains groundwater.

What is an unconfirmed aquifer?

An unconfirmed aquifer is an aquifer surrounded by a layer of impermeable rock or clay that impedes water flow.

What is a water table?

A water table is the uppermost level at which the water in a given area fully saturates rock or soil.

What is a spring?

A spring is a natural source of water formed when water from an aquifer seeps up to the ground surface. Signup and view all the answers

What is an artesian well?

An artesian well is a well created by drilling a hole into a confined aquifer. Signup and view all the answers

What is an Ogallala aquifer?

An Ogallala aquifer is the largest aquifer in the US with a surface area of about 450,000 km squared (175,000 miles squared). Signup and view all the answers

What is a cone of depression?

A cone of depression is an area lacking groundwater due to the rapid withdrawal by a well. Signup and view all the answers

What is saltwater intrusion?

Saltwater intrusion is the infiltration of salt water in an area where groundwater pressure has been reduced from extensive drilling of wells. Signup and view all the answers

What is a floodplain?

A floodplain is land adjacent to a river. Signup and view all the answers

What is an impermeable surface?

An impermeable surface is pavement or buildings that do not allow water infiltration. Signup and view all the answers

Which one is the largest river by volume?

The Congo Signup and view all the answers

When deep wells are heavily pumped, one result can be

A cone of depression Signup and view all the answers

Which is true of floodplains?

They have increased fertility Signup and view all the answers

Groundwater recharge

Is the result of precipitation Signup and view all the answers

How is a cone of depression formed?

A cone of depression occurs in an aquifer when groundwater is pumped from a well. Signup and view all the answers

How does saltwater intrusion occur?

Saltwater intrusion occurs by lateral encroachment from coastal waters and vertical movement of saltwater near discharging wells. Signup and view all the answers

Why is atmospheric water important?

Atmospheric water is the second most source of heat at the earth's surface. Signup and view all the answers

How do the recharge rates of a confined and unconfined aquifer differ?

Confined aquifers are fed by underground tributaries. Signup and view all the answers

Explain the difference between a confined and an unconfined aquifer.

A confined aquifer is an aquifer below the land surface that is saturated with water. An unconfined aquifer is an aquifer whose upper water surface is at atmospheric pressure and thus is able to rise and fall. Signup and view all the answers

Why is large scale use of water from a confined aquifer unsustainable?

Large-scale use of water from a confined aquifer is unsustainable because the withdrawal of water is not balanced by the recharge. Signup and view all the answers

Study Notes

Aquifers and Groundwater

An aquifer is a permeable layer of rock or sediment that stores groundwater.
A confined aquifer has an impermeable layer above it, restricting water flow; an unconfined aquifer is directly connected to the surface and water can move freely.
The water table indicates the highest level of water saturation in soil or rock.

Water Sources and Features

A spring occurs when aquifer water naturally flows to the surface.
An artesian well taps into a confined aquifer by drilling, allowing water to rise under pressure.
The Ogallala aquifer is the largest aquifer in the U.S. covering around 450,000 square kilometers (175,000 square miles).

Groundwater Impact and Challenges

A cone of depression forms around a well due to rapid water extraction, leading to a local drop in groundwater levels.
Saltwater intrusion can happen when freshwater groundwater is over-extracted, allowing saltwater to migrate into the aquifer.
A floodplain is the flat land adjacent to a river, which is prone to flooding and typically has fertile soil.

Water Management and Sustainability

Impermeable surfaces (like asphalt) prevent water infiltration, leading to increased runoff and potential pollution.
Groundwater recharge occurs primarily from precipitation, replenishing aquifers.
Confined aquifers receive water from underground tributaries, while unconfined aquifers are directly affected by surface conditions.

Key Water Dynamics

Large-scale extraction from confined aquifers can lead to unsustainable practices as withdrawals exceed recharge rates.
The rate of aquifer recharge varies significantly between confined and unconfined systems.
Atmospheric water is significant as it contributes to surface heat balance, influencing climate and weather conditions.

Trivia and Quiz Preparation

The Congo River is the largest river by volume, surpassing others like the Nile and Mississippi.
Depletion of groundwater from wells may lead to the formation of a cone of depression; this can impede groundwater recharge.
Floodplains enhance soil fertility, making them valuable for agriculture despite potential flooding risks.

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Description

Test your knowledge with these flashcards on important concepts from Geology Chapter 9, focusing on aquifers and water tables. Understand the definitions and differences between various types of aquifers and the water table's significance in groundwater. Perfect for reviewing key terms and concepts in geology.