Impact on Water

Impact on Water

Middle School

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Learning Objectives

• Explain how human population and consumption affect our water resources.

• Describe how Earth's processes cause uneven groundwater distribution.

• Analyze the environmental impact of changing water distribution.

• Identify major water pollution sources and their effects on Earth.

• Connect human impact findings to societal decisions and engineering solutions.

Key Vocabulary

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Salinity

Salinity is the measure of how much salt is dissolved in a body of water.

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Reservoir

A reservoir is a large, often man-made lake that is primarily used for a water supply.

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Aquifer

An aquifer is an underground layer of rock or soil that holds fresh groundwater for wells.

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Subsidence

Subsidence is the gradual process of the ground caving in or sinking over a large area.

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Algal Bloom

An algal bloom is the rapid and sudden increase in the population of algae in water.

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Dead Zone

A dead zone is an area in a body of water with low oxygen that can’t support life.

Key Vocabulary

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Gyres

Gyres are large, rotating systems of ocean currents that circulate water around the major ocean basins.

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Geoscience Process

A geoscience process describes the natural forces, like erosion or volcanic activity, that shape Earth's features.

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Per-Capita Consumption

Per-capita consumption measures the average amount of a specific resource that is used by each person.

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Non-renewable Resource

A non-renewable resource is one that is used faster than it can be replaced by nature.

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Human Water Use and Management

• A growing population uses more water for farming, transport, and recreation.

• The biggest use of water in the U.S. is for making electricity.

• Humans build dams across rivers to create reservoirs for storing fresh water.

• Reservoirs provide drinking water, irrigation, and generate hydroelectric power.

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Multiple Choice

What is the single largest use of water in the United States?

• Generating electricity

• Farming and irrigation

• Drinking and household use

• Recreation and transport

Multiple Choice

What is the relationship between a dam and a reservoir?

• A dam is a structure built to create a reservoir for water storage.

• A reservoir is a natural lake that a dam pumps water from.

• A dam filters water, while a reservoir distributes it to cities.

• A reservoir is a power plant, and a dam is the river it is on.

Multiple Choice

If a city's population grows quickly, which of the following best explains why that city might need to build a dam and reservoir?

• To meet the increasing demand for electricity and drinking water.

• To create new rivers for transportation.

• To prevent the population from growing any further.

• To lower the cost of water for recreational activities.

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Consequences of Altering Water Flow

Impacts of Dams

• Dams can increase erosion along stream banks and change the natural landscape.

• They act as barriers, preventing migratory fish from reaching their spawning areas upstream.

• Water blockage can cause rivers, like the Colorado River, to nearly dry up.

The Aral Sea

• In the 1960s, rivers feeding the Aral Sea were diverted for growing crops.

• As the sea shrank, its saltiness increased, which destroyed the local fishing industry.

• Wind spread contaminated salt from the dry lakebed, harming nearby crops and people.

Multiple Choice

What is the main outcome of significantly altering the natural flow of water?

• It can cause major changes to the environment and human activities.

• It helps to clean pollutants from rivers and seas.

• It increases the number of fish in all bodies of water.

• It makes the land surrounding rivers better for farming.

Multiple Choice

How can the construction of a dam lead to a decline in migratory fish populations?

• They increase the water's saltiness, which harms the fish.

• They create barriers that stop fish from reaching their upstream spawning areas.

• They wash away the food that the fish would normally eat.

• They make the river water flow too fast for the fish to swim.

Multiple Choice

If rivers that feed a large, freshwater lake were diverted for agriculture, what is a likely long-term consequence for the region?

• The local fishing industry could be destroyed by the lake becoming too salty.

• The soil around the dry lakebed would become very healthy for crops.

• The amount of fresh water available for people would increase.

• The river would flow faster and cause less erosion along its banks.

Groundwater and Geologic Processes

• Earth's freshwater is unevenly spread out due to long-term geologic processes.

• Groundwater is stored in underground aquifers, formed by past geologic processes.

• Groundwater is a limited resource that can take thousands of years to replenish.

Multiple Choice

According to the information provided, where is groundwater stored?

• In underground aquifers

• In rivers and lakes

• In oceans and seas

• In clouds and vapor

Multiple Choice

What is the relationship between geologic processes and the location of freshwater resources?

• The long-term geologic processes that create them happen unevenly.

• Some areas get much more rain than others.

• Humans use water faster in certain locations.

• Rivers carry all the water to one place.

Multiple Choice

If a town pumps large amounts of water from an underground aquifer, what is the most important long-term risk they should consider?

• The aquifer is a limited resource that could be used up because it takes thousands of years to refill.

• The water is likely contaminated from ancient rocks and is unsafe to drink.

• The geologic processes that formed the aquifer could reverse and make it disappear.

• The water will eventually flow into the oceans and become salty.

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Impacts on Groundwater

• Much of Earth's freshwater is groundwater, stored underground in layers called aquifers.

• We use wells to access this water for about 20% of our daily needs.

• Taking too much water can cause wells to run dry and the land to sink.

• The empty space underground can collapse, creating dangerous sinkholes.

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Multiple Choice

What is groundwater?

• Freshwater stored underground in layers called aquifers

• Water that flows in rivers and lakes on the surface

• Saltwater found deep within the Earth's oceans

• Water frozen in glaciers and ice caps

Multiple Choice

What is the relationship between human water use and groundwater levels?

• It can cause wells to run dry and the land to sink.

• It increases the total amount of freshwater on Earth.

• It cleans the pollutants from the underground layers.

• It prevents the ground from collapsing.

Multiple Choice

A small town relies entirely on well water. If the town's population doubles, what is a likely long-term consequence for the land?

• The town may be at a higher risk of developing sinkholes.

• The aquifers will likely expand to hold more water.

• The groundwater will automatically become cleaner.

• The land level will rise as more water is removed.

Sources of Water Pollution

• Runoff from farms contains fertilizers and pesticides that pollute water.

• Factories and mines can release harmful chemicals into our water.

• Rain washes oil and other pollutants from cities into rivers.

Multiple Choice

What is the common factor that makes farms, factories, and cities sources of water pollution?

• The release of harmful substances from human activities

• Natural purification processes in rivers and lakes

• The seasonal migration of aquatic animals

• The process of water evaporation and condensation

Multiple Choice

How do pollutants like fertilizers from farms and oil from cities typically reach rivers?

• They are buried deep underground.

• They evaporate into the atmosphere.

• Rain washes them into the water.

• They are absorbed by plants for food.

Multiple Choice

A community is built on a hill above a river. During a heavy rainstorm, what is the most likely impact on the river?

• The river's water level will decrease significantly.

• The river will become cleaner due to the extra water.

• Pollutants from the community will be washed into the river.

• The rainstorm will have no effect on the river's water quality.

Ocean Pollution and Dead Zones

• Pollution, mostly from land, enters the ocean through runoff and from the air.

• Excess nutrients from pollution cause large, harmful algal blooms to grow.

• When algae decompose, they use up oxygen, creating deadly "dead zones".

Multiple Choice

What is the direct cause of large, harmful algal blooms in the ocean?

• Excess nutrients from pollution

• A lack of oxygen in the water

• The decomposition of marine animals

• Runoff from clean rivers and streams

Multiple Choice

What is the relationship between the decomposition of algae and the creation of 'dead zones'?

• Decomposition uses up oxygen, which creates dead zones.

• Decomposition releases nutrients, which algae use to grow.

• Decomposition cleans the water, which removes pollution.

• Decomposition makes the water colder, which fish cannot survive.

Multiple Choice

If a community successfully reduces the amount of pollution and excess nutrients flowing into the ocean from its land, what would be the most likely long-term effect on the nearby marine environment?

• A decrease in the frequency and size of dead zones.

• An immediate increase in the fish population.

• An increase in the number of harmful algal blooms.

• A decrease in the oxygen levels in the water.

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Monitoring and Minimizing Impacts

• Science explains the impact of human actions on the environment.

• Society uses engineered solutions and laws to reduce these impacts.

• The U.S. Clean Water Act is a law created to reduce water pollution.

• You can help by conserving water and recycling plastics.

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Multiple Choice

What is the primary goal of creating engineered solutions and laws like the U.S. Clean Water Act?

• To reduce the negative effects of human actions on the environment.

• To provide more resources for building factories.

• To make it more difficult for scientists to study pollution.

• To encourage people to use more water and plastic.

Multiple Choice

What is the relationship between the U.S. Clean Water Act and the action of recycling plastics?

• Both are examples of actions taken to reduce environmental harm.

• The Clean Water Act is a law, while recycling is a scientific theory.

• Both actions are exclusively focused on creating more plastic.

• Recycling plastics is a cause of water pollution.

Multiple Choice

A scientific study shows that a new factory is causing pollution in a local river. Based on the information provided, what is a logical conclusion about how this problem could be handled?

• Society can use laws and engineering to address the factory's pollution.

• The only possible solution is for individuals to recycle more plastic.

• Science can identify the pollution, but cannot help create a solution.

• The problem is not related to human actions and will fix itself.

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Common Misconceptions

Misconception	Correction
Most ocean pollution comes from oil spills at sea.	Over 80% of ocean pollution originates from land-based activities like urban runoff.
The effects of diverting a river are only local.	Altering a river can change a region’s climate and affect distant economies.
There is an endless supply of freshwater.	Only 3% of Earth’s water is fresh, and much of it is non-renewable.

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Summary

• Rising population and consumption increase the demand for limited freshwater.

• Earth's processes have unevenly distributed water, making it a limited resource.

• Altering water flow with dams and overuse of groundwater can harm the environment.

• Societies use science, engineering, and laws to manage and conserve water.

Poll

On a scale of 1-4, how confident are you about the concepts covered in today's review?

• 1

• 2

• 3

• 4