Geography - Rivers and Oceans - Lesson #4

Question 1

• What is river diversion?

* What are the three types of river diversions?

Answer 1

• River diversion is changing the course of a river in order to meet a need.
• The three types of river diversions are canals, dams and river channels.

Question 2

What are canals?

Answer 2

A canal is an artificial waterway built to allow the passage of boats or to divert water.

Question 3

What are the benefits of building wells? (3)

What are the negative effects of building wells? (1)

Answer 3

Benefits:

• method used for transporting materials.
• used to supply cities with water.
• can create environmental benefits.

Negative effects:
-may harm the environment. (e.g. a canal that diverts water from a river can change its flow and alter the local habitats, both in the river and on the land nearby)

Question 4

What are dams?

Answer 4

A dam is a barrier that is built across a river.

Question 5

What are the positive effects of dams? (2)

Answer 5

Positive effects:

• as the water passes through the dam, it turns blades on a turbine, which converts the energy from the falling water into electricity.
• the dam raises the water level behind it. The higher water level widens the river or even creates a new lake. Known as a reservoir, this water can be supplied to farms, industries and communities.

Question 6

What are the harmful effects of dams? (4)

Answer 6

Harmful effects:

• they change the flow and levels of rivers, which can affect erosion. This can damage the river ecosystems and those that might feed into, such as wetlands or bogs.
• many native species of animals and plants cannot survive.
• invasive species may move in.
• people living in what will be the new reservoir area are forced to move away.

Question 7

Why do people create new river channels? (2)

Answer 7

• People create new river channels to redirect the flow of water from rivers.
• Sometimes this is done to bring water to farmland.

Question 8

What are the Aral Sea’s negative results when they created a new river channel in it? (4)

Answer 8

• the Aral Sea’s water begin to evaporate, and the sea begin to shrink.
• caused the salt levels to increase which caused all the fish to die because of the saltier environment
• part of the seabed became a desert.
• millions of tonnes of salt from the seabed were carried by wind and rain onto a wide area of pastures and farmlands, harming local vegetation and crops.

Question 9

When is water polluted?

Answer 9

water is polluted when people change it in a way that makes it harmful or poisonous for people or other living organisms to use.

Question 10

• What human activities can cause pollution. (3)

* What does water pollution harm

Answer 10

Human activities that can cause pollution:

• factories
• fertilizers
• pesticides washing off lawns and farmers’ fields, and car and airplane exhaust which is burned gas from an engine

water pollution harms the whole global environment, including people, wildlife, and plants.

Question 11

• What is sewage?

* how many people does it kill a day?

Answer 11

Sewage is the waste liquids from sinks, bathtubs and showers, toilets, and other drains in households, schools, offices, and businesses. It kills 14 000 people a day.

Question 12

In some communities sewage is treated from contaminants before it is returned to waterways, but sometimes it is not.

• what can untreated sewage in waterways contain? (2)
• how can this effect people and can other living species be effected by it?

Answer 12

• untreated sewage in waterways can contain bacteria or viruses.
• This can cause people to become ill or die if they consume it. Other living species can also be affected by the poor-quality water.

Question 13

How do people change oceans? (3)

Answer 13

• when people harm rivers he damage flows downstream, to the lower part of the stream or river. Eventually this damage arrives at the ocean.
• people also change oceans directly. How we manage out fisheries affects the survival of species and ocean habitats.
• we are contributing to climate change which affects oceans, and we are also polluting oceans.

Question 14

How do people destroy ocean habitats?

They destroy coral reefs, what are coral reefs?

Answer 14

• peoples activities can destroy habitats that border the oceans, such as sea grasses and mangrove swamps.
• coral reefs: complex environments that are underwater ridges made up of living coral and their skeletons, and they are also communities of other organisms, such as plants, fish, turtles, starfish, and so on. They are home to over a quarter of marine life on earth and are important for nurseries for fish and also provide protection during storms. They grow slowly in clear, shallow, warm water.

Question 15

Why can loss of habitat happen? (5) (mainly about coral)

Answer 15

• fish nets dragged along the ocean floor break the coral and disturb sediment. The sediment smothers nearby reefs.
• poor farming practices result in large amounts of soil washing off the land into oceans. These sediments also smother reefs and sensitive ocean bottoms.
• tour boats collide with the fragile coral reefs, breaking the coral. Divers may break off chunks of the reef for souvenirs.
• people mine coral to use as road-fill or bricks in new buildings.
• many kinds of toxins dumped into the ocean or carried there by rivers are poisoning the reefs. Some chemicals such as nitrogen, are fed on by algae. When the algae multiply in large numbers, they block the sunlight, which the coral needs to grow.

Question 16

What are the four ways pollution ends up in oceans?

Answer 16

It can be dumped directly into oceans from the land, which is what sometimes happens with sewage, or from ships or ocean drilling rigs. It can also enter the ocean from rivers, from the air, or through natural forces such as tsunamis and hurricanes.

Question 17

What are the three other important types of ocean pollution (besides garbage and sewage)

Answer 17

• Toxic wastes: They are poisonous chemicals such as pesticides, and metals, such as mercury. Many chemicals are used by industries to make products. They are dumped into the water as waste and eventually end up in the oceans. Toxic chemicals can dissolve out of plastic, and many of them never break down. These chemicals become more concentrated as animals eat each other. Some animals cannot reproduce, or they get sick, and they can die.
• Fertilizers: Farmers put fertilizers on their fields to help their crops grow. Over time a water system such as a stream or a river, brings the fertilizers to the ocean. These nutrients make algae in the water grow quickly, which will make the algae use up all the oxygen in a zone of water so there is none left for other animals such as fish.
• Oil: Oil spills happen when oil tankers or drilling platforms are damaged. Much more oil is released into the water on purpose through ships flushing out their oil tanks. Other sources of oil pollution in oceans are oil-drilling activities and runoff from highways and parking lots.