Changing Waterways PRACTICE

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.

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.

c. results from industrial activity

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

a. supplies heat to polar regions

c. increased water levels

c. are set up around natural resource areas

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.

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.

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.