Watersheds and Wetlands

Env. Science and Ecology Standards 4.1

Lesson 1.1 The Blue Planet

Objectives:• Explain why fresh water is a precious

resource.• Describe the parts of the water cycle.• Identify and describe the major watersheds

of the U.S. and PA.• Describe the characteristics of streams and

rivers.

Water, water everywhere, but….

• Earth is known as the blue planet:– 70% of the Earth’s surface is covered in water.– The Earth and its atmosphere contain

~336million cubic miles of water!– Each person on earth could have 1 trillion

gallons if the water was divided evenly!!

Are we worried about water?Yes or no. Why?

• If there’s so much water…

• Why are water shortages a problem?– 97% of the Earth’s water is salt water!– Only 3 % is freshwater– Of that 3% of freshwater, 77% is frozen in the

ice caps/glaciers!– 22% is found in the ground.– Only 1% is surface water; found in lakes,

rivers, ponds, and the atmosphere.

Where’s the Water?

• Imagine….drinking a cool glass of water – ah….where did that water come from?

• Much of our water has been on earth since the Earth was first formed.

• Water is considered a renewable resource.• Water is endlessly cycled through the water

cycle.

The Water Cycle

• Water can exist as a solid (ice), a liquid, or as a gas (water vapor).

• These forms move through the environment through the water cycle.

• The water cycle is an unending circulation process powered by the sun that distributes water throughout the Earth.

The Water Cycle

The processes involved in the water cycle.

1. Evaporation occurs when the heat of the sun’s energy converts water on the surface from liquid to gas. Most evaporation takes place in the oceans.

The Water Cycle

2. Condensation takes place when the water vapor cools enough to return to a liquid or solid state. Clouds are made out of condensed water vapor.

3. Precipitation occurs when liquid (rain) or solid (snow & hail) water falls to Earth.

The Water Cycle

4. Transpiration occurs when plants release water vapor from their leaves into the air.

5. Runoff is the water that flows into streams, rivers, lakes, and ponds. (Surface water)

The Water Cycle

6. Infiltration/Percolation occurs when rain and melting snow seep into the ground. (Ground water)

Did you remember how much of the Earth’s fresh water is stored in the ground?

One of the main reasons people live longer today than

they did 200 years ago is clean water.

Do you agree or disagree with this statement?

What are some ways humans are affecting the water cycle?

In what steps of the water cycle should we be most concerned about?

The entire area of land that is drained by a

river is called it’s watershed or

drainage basin.

Characteristics of a Watershed• Watersheds are surrounded by topographic

highs called divides.– A divide can be several or thousands of feet

high. A divide is any ridge between two streams along which precipitation runs off.

– Where are the major continental divides located in the U.S.?

Topographical Map

*Lines show elevation.

(typically 20ft apart)

*From this information, you can determine(or delineate) which way water will flow.

(typically water flows perpendicular to contour lines.

Amazon Watershed

Major Watersheds in the U.S.

Turtle Creek Watershed

Watersheds of Pennsylvania

Pennsylvania Watersheds

• All of Pennsylvania’s water eventually drains into the Atlantic Ocean.

• The Pa State Water Plan organizes the state into 104 watersheds, which are divided into basins and sub-basins.

Pennsylvania Watersheds

Pennsylvania Watersheds

Pennsylvania Watersheds

Pennsylvania’s Watersheds

PA’s Watersheds Continued…

• Five Major Watersheds– 1. Great Lakes Basin

• A. Subdivided into two– 1. Erie Basin – empties into Lake Erie.– 2. Genesee Basin – empties into Lake

Ontario.

• 2. Ohio River Basin– A. We live in it!– B. Second Largest watershed in PA– C. Covers almost 16,000 square miles– D. Supplies Drinking water to about 13 million

people (3.5 million in PA)– E. Part of the Mississippi watershed.

• 3. Susquehanna / Chesapeake Basin– Largest Watershed in PA– Covers 46% of the state.

• 4. Potomac Basin– Even though the Potomac River doesn’t flow

through PA – a small portion of its watershed is in PA.

• 5. Delaware Basin– Third largest watershed in PA– Covers about 6,500 square miles

The amount of water that falls on a watershed varies from year to year and can have a

significant effect on the amount of water that a river

carries.

Origins of a River

1. A river (or stream) begins at a place called the source or headwaters.

2. The place where a river (or stream) ends by flowing into another body of water is called the mouth.

3. Water flows in either one of two ways:

1. Laminar flow is when the water moves in straight paths are parallel to the stream’s channel.

2. Turbulent flow occurs when water moves in tiny circular paths as it flows downstream.

Which one mixes the water the best?

4. A stream’s velocity often determines whether its flow will be laminar or turbulent.

• Faster velocity results in turbulent and slower velocity results in laminar.

• True laminar flow is rarely seen in natural streams.

5. River Sediment can be carried one of three ways:

• Dissolved load in the water (smallest) ex.

• Suspended load in the water (small) ex.

• Bed load carried along the bottom. (large) ex.

6. Rivers deposit sediment when there velocity slows.

-form bars near bends.

-in flood plains when it overflows or floods its banks.

-near the mouth of the river.

Major Rivers in PA

• Ohio• Allegheny• Monongahela• Youghiogheny• Genesee• Susquehanna• Juniata

• Delaware• Lackawanna• Lackawaxen• Lehigh• Schuylkill• Clarion