Lesson 3: Water Above the Ground

Part One

Where do we find water?

Water on Earth is found either above the ground or below the ground.

Water found above the ground is called surface water. That’s because it is located or seen on the Earth’s surface. Oceans and rivers are examples of natural surface water bodies. Streams, lakes and ponds are other examples. In Florida, surface water bodies also include wetlands such as marshes and swamps.

Most surface water bodies are natural. Others are artificial, or built by man. Man-made lakes and ponds are often found at parks or golf courses.

Basins used to collect and store water are called reservoirs.

Reservoirs are often built near cities which do not have their own water sources. Water is piped in from rivers or lakes. It is then stored in a reservoir until needed.Reservoirs are often created by building a dam in a river. The water from the river is diverted (channeled) into a reservoir for storage. Sometimes dams are built on Florida’s rivers to divert water for storage. This does not occur often, because land surface is too flat in most places to store much water without taking up lots of land. Reservoirs are more common in hilly states like Georgia and South Carolina.

Part Two

The area where water drains off the land into a river or lake is called a drainage basin or watershed. Water that drains off the land is called runoff. Many things determine the runoff in a drainage basin.

Water moves slowly along flat land or a gently sloping hill. When the water moves slowly, it can evaporate or soak into the ground.

A steep slope will cause water to flow more quickly into a surface water body. That’s why drainage basins with steep slopes often flood.

Objects such as plants, trees and grass help to slow the water flowing through a basin. Water runs more swiftly over bare or paved surfaces. Can you guess why? There is nothing to slow it down. Trees and other plants also help to hold water on or above the ground. By doing so, they allow water time to soak into the ground or to evaporate.

Part Three

How does water move through soil?

Different kinds of soil have differing abilities to hold water — some more, some less. Water moves more quickly and easily through layers of sand and gravel than through clay. This is because clay is not as permeable as sand or gravel. Permeability has to do with how fast water can flow through an object. Because clay particles fit tightly together, water doesn’t flow through clay very easily. So clay is said to be impermeable.

What happens to all that rain?

The next time it rains, watch what happens to the water running off the sidewalk or street near your home. Then watch the water that falls on ground covered with trees, grass or other plants. Notice which type of surface has the faster-flowing water. Rainwater that runs off a paved or unpaved surface and does not soak into the ground is called stormwater runoff. This water usually flows into the nearest body of water.

Part Four

Stormwater runoff is one of the main causes of pollution of rivers and lakes.

When rainwater flows over paved surfaces, it picks up many things present on the ground. Examples include oil, gasoline, chemicals, pesticides and fertilizers. These materials mix with the rainwater and are carried back to water bodies.

This runoff causes pollution to our waterways. Later we will talk more about causes of water pollution and ways to stop it.

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