Watersheds and Water Movement

The image shows how water travels through a flower pot. How can this model be used to represent watersheds?

• This model represents surface water runoff because the water moves from the surface of the dirt to the bottom.

• This model represents groundwater because the water seeps from the surface into the bottom of the pot.

• The model represents a reduction in erosion, which allows more groundwater pollution.

• This model represents how the roots of crops eliminate pollution by filtering all moisture in the ground.

Answer explanation

This model illustrates groundwater as it shows water seeping from the surface into the bottom of the pot, similar to how water infiltrates the ground in a watershed.

Using your answer from Part A, where this model represents a watershed, which of the following statements demonstrates the significance of watersheds?

• Pollutants, such as fertilizers and gasoline, end up in major waterways via watersheds.

• Pollutants, such as fertilizers and gasoline, are isolated in small areas because the dirt traps them.

• Groundwater is unaffected by pollutants because it is a self-renewing resource.

• The potted plant demonstrates that humans have little negative impact on the environment through pollution.

Answer explanation

The correct choice highlights that watersheds play a crucial role in transporting pollutants like fertilizers and gasoline to major waterways, demonstrating their significance in environmental health.

In an agricultural area, a heavy rainfall caused a flash flood. The topsoil from a freshly fertilized field washed into a local stream. As a result, the amount of nitrogen in the water drastically increased, causing the algae to grow to record levels and cover the surface of the stream. What effect did this bloom of algae have on the stream?

• The animal life in the stream was benefited since most fish eat algae.

• The algae upset the balance of carbon dioxide and oxygen in the water, causing fish to die.

• The algae acted as a blanket on the stream, causing the water temperature to increase and the fish to thrive.

• The algae brought in a predator that ate the local fish.

Answer explanation

The algae bloom disrupted the balance of carbon dioxide and oxygen in the water, leading to hypoxia. This condition can cause fish to die due to lack of oxygen, making this the correct choice.

A company known as Husvar Industries is wanting to build a factory in the watershed that is pictured. The company wants to limit the ecological impact it has on surrounding areas. Which locations would be the worst locations for the factory to be placed?

• Near the river source and on the hilltop.

• In the valley and near the river source.

• On the hilltop and near the forest.

• Near the forest and in the valley.

Answer explanation

Placing the factory near the river source risks contaminating water and disrupting ecosystems. The hilltop location can lead to erosion and runoff issues, making these the worst choices for minimizing ecological impact.

Pollution from human activity often ends up in lakes and oceans due to watersheds. Which part of the diagram is most responsible for this movement?

• Precipitation

• Condensation

• Runoff

• Evaporation

Answer explanation

Runoff is the process where water moves over land, carrying pollutants from human activities into lakes and oceans. This makes it the most responsible part of the watershed diagram for the movement of pollution.

A company known as Husvar Industries is wanting to build a factory in the watershed that is pictured. The company wants to limit the ecological impact it has on surrounding areas. What location would limit the ecological damage?

• At the top of the river.

• Away from the river.

• At the middle of the river.

• At the bottom of the river.

Answer explanation

Building at the bottom of the river minimizes ecological damage by reducing disruption to the watershed. This location is less likely to affect upstream habitats and water quality compared to other options.

Based on the chart, what approximate percentage of the items result from the action of people?

• 25%

• 50%

• 65%

• 75%

Answer explanation

The chart indicates that 75% of the items are a result of people's actions, making this the correct choice. The other percentages do not accurately reflect the data presented.

Ft. Worth and Dallas are in the same drainage basin. What is the most likely reason that the water in the Trinity River is dirtier in Houston than it is in Dallas?

• Ocean pollutants are entering the river.

• Pollutants are entering from other drainage basins.

• The river basin picks up more human pollutants.

• The water goes through a salt dome and gets more polluted.

Answer explanation

The river basin picks up more human pollutants in Houston due to higher population density and industrial activity, leading to increased contamination compared to Dallas.

A local gardener puts fertilizer on his plants. The plants are very healthy, but what is a negative effect the fertilizers have on the environment?

• Excess fertilizer is washed into local streams, causing an overgrowth of algae.

• The fertilizer builds up in the soil and causes more weeds to grow over time.

• The fertilizer evaporates, causing acid rain to fall on the neighborhood.

• The fertilizer pollutes the groundwater causing an overabundance of producers.

Answer explanation

Excess fertilizer can run off into local streams, leading to nutrient pollution. This causes an overgrowth of algae, which depletes oxygen in the water and harms aquatic life, making it the most significant negative environmental effect.

Marine dead zones can form when nutrient run-off causes certain types of algae to grow very quickly and then die off. As dead algae decompose oxygen is removed from the water. With less oxygen available, fish and other marine animals can die. What would be one practical way to reduce dead zones?

• Add bacteria that are able to eat the fast-growing algae.

• Harvest marine fish in dead zone areas to reduce oxygen use.

• Pump oxygen into the water using equipment on fishing vessels.

• Prevent fertilizer and other wastes from entering rivers and streams.

Answer explanation

Preventing fertilizer and waste from entering rivers and streams directly addresses the root cause of dead zones by reducing nutrient run-off, thus limiting algae growth and subsequent oxygen depletion.