Changing Waterways PRACTICE

Explain how flooding affects rivers and how flooding can be influenced by human activity.

c. Flooding causes changes to the shape of rivers by eroding the river’s channels. Flooding also causes changes to floodplains, as sediments are deposited in floodplains during flooding. The building of levees and dams can cause flooding to be more damaging to floodplains and river courses, as they change the course and outlets of the river.

How can buffer strips have a positive impact on waterways?

Buffer strips can decrease erosion rates, as vegetation acts as an anchor to soil. They can also decrease the amount of pollutants entering waterways by slowing runoff from agriculture and soaking up some pollutants before they enter waterways.

Ocean and freshwater contamination _______.
a.
does not affect marine life
b.
is not affected by agriculture
c.
results from industrial activity
d.
is independent of human activity

c. results from industrial activity

Which of the following statements about the effects of pollution on marine ecosystems is true?

a.
Burning fossil fuels causes a direct increase in the temperatures of ocean water.
b.
Burning fossil fuels causes a decrease in the pH of ocean water making it more acidic.
c.
Pollution in marine ecosystems causes a decrease in the formation of algal blooms.
d.
Addition of warm water has no effect on marine ecosystems.

b. Burning fossil fuels causes a decrease in the pH of ocean water making it more acidic.

Thermohaline circulation _______.
a.
supplies heat to polar regions
b.
causes salt lake formation
c.
causes oxbow lake formation
d.
is unaffected by heat fluctuations

a. supplies heat to polar regions

Which of the following is not an effect of erosion on lakes?
a.
water leakage
b.
wearing away of sides
c.
increased water levels
d.
basin filling with sediment

c. increased water levels

Buffer zones _______.
a.
can help regulate the acidity of aquatic ecosystems
b.
help increase erosion rates
c.
are set up around natural resource areas
d.
all of the above

c. are set up around natural resource areas

Explain how thermohaline circulation is influenced by salinity and temperature.

Thermohaline circulation is influenced by changes in density gradients. These density gradients are affected by the salinity and temperature of the ocean’s water. Cold water is denser than warm water and salt water is denser than freshwater. As water cools off, it sinks. As water evaporates, the salt concentration of the remaining water increases because the salt from the evaporated water remains. This causes the water to sink and circulate.

Explain how pollution affects marine life.

Pollution affects marine life in a variety of ways. Pollution from fertilizers can cause an increase in phytoplankton, which can result in the formation of algal blooms. Pollution can damage coral reefs, which are vital to many forms of marine life. The introduction of toxic chemicals to ocean water can lead to the death of marine life. Ocean currents can carry pollutants throughout the ocean, affecting areas that may not be directly affected by human activity. Soaps and detergents can increase the pH of ocean water. Solid wastes can damage and kill marine organisms as well.

How can alternative practices reduce human impact on waterways?

Human activity has a great impact on waterways. Decreased amounts of vegetation leads to erosion of water banks. Increased fertilizer and nutrients levels in water from agriculture, sewage, and industry lead to the formation of algal blooms and subsequent decrease in other aquatic organisms. Chemical and oil spills in waterways leads to the death of aquatic organisms as well. Regulation of industry, agriculture, and recreational activity can help reduce human impact on waterways. An increased awareness of human impact on waterways through education can lead to a decreased impact as well.