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infinity-project.orgThe Caruth Institute for Engineering Education

Engineering Education for today’s classroom.

Engineering Earth



Unit 2: Water and the Environment



Unit 2: Objectives

Students will investigate how water availability affects our lives.

Students will learn about watersheds and their relevance to people.

Students will discover how different factors contribute to water quality and how water quality is monitored.



Section 1: Water and Watersheds



The Water Cycle and Water Balance

326 million cubic miles of water on Earth Each cubic mile represents over a trillion gallons. Over 90% of water on Earth is salt water. Less than 10% of water on Earth is freshwater.

33% of freshwater is groundwater ~65% of freshwater is ice Less than 1% in rivers, lakes, and streams



Water Concerns

Globally Conserved Does Not Mean Locally Conserved Fluctuations in precipitation and loss of vegetation can

dramatically affect local water availability. The loss of groundwater and meltwater creates vulnerabilities.

Examples: Sahara: desertification Lake Superior: shrinking



What Is a Watershed?Land Areas That Shed Their

Water into a Particular River Elevation of land and the

composition of soil and rock help to determine where water goes.

Ridgelines outline watersheds.

Networks Small streams combine to form

larger streams, which combine to form rivers.

Not Just Surface Water Water infiltrates soil and rock to

become groundwater.



The Physics of Watersheds I

Potential Energy: PE = mgh Stored energy Arises because of gravity Changes with elevation

Kinetic Energy: KE = 0.5mv2

Energy associated with water movement Strongly associated with water velocity

Total Energy: PE + KE + frictional

losses As PE is lost, KE is gained and vice versa. Some energy is lost due to friction between

the water and the streambed.



The Physics of Watersheds II

Stream Course Water pursues the course of least resistance, always descending if possible. Streams can change course over their lifetime due to erosion and fluctuations in

water volume. “Meanders,” the sinusoidal curves characteristic of many streams, serve to control

stream velocity and are a sign that the stream is in equilibrium.

Continuity Equation: Changes in the cross-sectional area of a stream also change its velocity, all else

being equal.

Discharge: Discharge is the volume of water passing a given point along the stream per unit

time and is often used instead of velocity, since velocity can be misleading.

A1 V1 A2 V2

Q AV



The Physics of Watersheds III

Manning’s Equation: Relates discharge Q to:

Slope, S Hydraulic radius, R Perimeter of the cross section in contact with water, PW Stream bed roughness, n

Includes frictional and energy effects on the stream Applies to open water channels in general

Erosion Collisions between flowing water and the streambed or streambank cause the

stream to lose energy while picking up sediment, causing erosion. Erosion increases with velocity, as does debris carried.

Q AR0.66 S0.5 / n , where R A / P

w



Exercise 2.1

The Physics of Watersheds Exercise 2.1

Use physics to solve problems involving stream mechanics.



Activity 2.1

The Physics of Watersheds—LabVIEW Activity 2.1

Use LabVIEW to compare the energy equation to Manning’s open change flow equation to see how well each equation models water discharge.



Activity 2.2

Water Erosion Prediction Project Activity 2.2

Have the class split into teams and compete to see who can use the USDA WEPP software to engineer a slope with the lowest annual soil erosion.



Ecosystem ServicesProvisioning Services

Regulating Services

Cultural Services

Support Services

Provisions that come from biological productivity: food, fiber, forage, fuel, and biochemicals

Freshwater

Water purification and regulation

Pollination and seed dispersal

Climate regulation through vegetation cover and carbon storage

Recreation and tourism

Cultural identity and diversity

Cultural landscapes and heritage values

Indigenous knowledge systems

Spiritual, aesthetic, and inspirational services

Soil formation and development

Primary production

Nutrient cycling



Water Footprint

Use Principles for Calculating Ecological

Footprints to Determine Water Footprint Industrial and agricultural use: 278 billion gallons/day Domestic residential use: 4 billion gallons/day Cutting back requires:

A reduction in “visible” water usage Increased efficiency in products or services that are water

intensive

Ways to Conserve Water Industrial/agricultural: renewable energy sources, drip

irrigation, and no-till farming Residential: no-flush toilets, automatic sinks, and low-

pressure shower heads

infinity-project.org the caruth institute for engineering education engineering education for...

Documents

water volume

volume of water

water quality

flowing water

water balance326

water movement

salt water

water velocitytotal