Agua es vida (Water is life [1])—that statement adorned the logo of a water-well-drilling company I worked with many years ago in Puerto Rico, and to me, the phrase highlights the importance of water on Earth. Remember that 78% of a human baby's body is composed of water, as is 55–60% of an adult's body; obviously, water is a truly critical component of sustaining life on Earth.
Water covers ~70% of Earth's surface. Most of this is in the oceans, a realm of Earth not covered in this course. However, the global ocean is more than peripheral to the Critical Zone. Ultimately, all of the water that bathes the Critical Zone was evaporated from the ocean surface, transferred to the continents as vapor via the atmosphere, and deposited on the land surface as liquid or solid precipitation, depending on regional climate. In this unit, we will learn about water's role in the Critical Zone. We will accomplish this in Lesson 6 by first considering in some detail the so-called water cycle. Because of the role of the atmosphere, we will revisit some aspects of atmospheric processes. This should serve to demonstrate the intimate link between the various "spheres" (our last unit with this one) that overlap in the Critical Zone!
The water cycle involves much more than the transfer of water from the ocean to the land surface. Once precipitated, water can flow across the land surface, infiltrate into the subsurface as soil pore water or groundwater (remember that the base of the Critical Zone is defined as the depth to which groundwater freely circulates), or be evaporated or transpired by plants (the top of the Critical Zone!) back to the atmosphere. In this lesson, we will consider the many processes involved in the flow of water through the Critical Zone.
Water is known as the universal solvent—rarely is it found in a pure state because many substances will readily dissolve in it. Thus, we will include brief considerations of water chemistry and quality (we will return to this topic again when considering landforms and biota) and the role human society has played in degrading this invaluable resource. In our landform unit, you will also learn about the role water plays in transforming and sculpting the land surface, while in the biota unit we will explore the many interactions between water and life in the Critical Zone, thus further linking the Critical Zone "spheres."
Finally, because of the somewhat mysterious nature (out of sight, out of mind) of groundwater, you will study various aspects of groundwater flow in Lesson 7, and complete the water unit by reading about links between water and Critical Zone science. Enjoy.
In an earlier lesson, I described soil as the "heart" of the Critical Zone. With that analogy in mind, perhaps you can consider water to be the “blood” of the Critical Zone. Once precipitated onto a landscape, water can be stored at the surface in various reservoirs depending on the climate of a region, flow across the surface, or infiltrate into and flow through the subsurface domain. Along the various pathways, water can transfer dissolved constituents from one portion of the Critical Zone to another. Those constituents may degrade water quality, precipitate minerals, or provide sustenance for life, among many other processes. As in earlier lessons, you should not be concerned with memorizing and repeating various definitions for the many processes you will read about and study. Instead, begin by securely grasping the concept of the water cycle. Once you have mastered the water cycle, move on to learn about the chemistry of natural waters and human influences on water in the Critical Zone.
What will we learn about in Lesson 6?
By the end of this lesson you should be able to:
Lesson 6 will take us one week to complete As you work your way through these online materials for Lesson 6, you will encounter additional reading assignments and hands-on exercises and activities. The chart below provides an overview of the requirements for Lesson 6. For assignment details, refer to the lesson page noted.
Please refer to the Calendar in Canvas for specific time frames and due dates.
ACTIVITY | LOCATION | SUBMISSION INFORMATION |
---|---|---|
Report on StreamStats | page 6 | Post to the Lesson 6 - StreamStats dropbox in Canvas dropbox |
If you have any questions, please post them to our Questions? discussion forum (not e-mail), located under the Discussions tab in Canvas. I will check that discussion forum daily to respond. While you are there, feel free to post your own responses if you, too, are able to help out a classmate.
The term "water cycle" does not refer to water craft you can peddle across water—instead the water cycle describes the transit of water through all of the components or "spheres" of the Critical Zone (atmosphere, hydrosphere, lithosphere, biosphere, and soil) and the processes involved in that transit.
The chemistry of natural water, aqueous chemistry (or aqueous geochemistry), is a complex subject well beyond the reach of this course. However, some very basic concepts of water chemistry are important to help understand the role of water in the Critical Zone.
Humanity's use of water has a long history for obvious reasons—agua es vida! Civilization is thought to have first arisen in the Tigris-Euphrates River Valley, where irrigation canals have been used for at least 6,000 years. In addition, the site of vast water bodies (lakes, oceans) or flowing water in rivers and streams, provide aesthetic appeal and comfort for many, as well as providing sources for food, waste disposal, and recreation. For these reasons among others, humans have lived and worked near water, exerting strong and important influences on the water cycle, water quantity, and quality.
USGS has placed much of its surface water gauging data online using a Web-based tool called Streamstats. In this exercise, you will learn to use Streamstats to gather information about a study site. Ideally, this study site will be the same as the soil site you identified in Lesson 2. However, you will see that not all of the states have fully implemented this tool, so if you are from a state other than Pennsylvania and chose a soil site in that state, you may not be able to use Streamstats to evaluate your soil site. Read on.
For this assignment, you will need to record your work on a word processing document. Your work must be submitted in Word (.doc) or PDF (.pdf) format so I can open it. In addition, documents must be double-spaced and typed in 12 point Times Roman font.
L6_surfacewaterstudies_AccessAccountID_LastName.doc (or .pdf).
For example, student Elvis Aaron Presley's file would be named "L6_surfacewaterstudies_eap1_presley.doc"—this naming convention is important, as it will help me make sure I match each submission up with the right student!
Upload your report to the "Lesson 6 - Surface Water Studies Activity" dropbox in Canvas (in the lesson under the Modules tab) by the due date indicated on our Canvas calendar.
You will be graded on the quality of your writing. You should not simply write responses to the questions and submit them to me. Instead plan on writing a short stand-alone paragraph (or page or whatever you decide is necessary considering any constraints I might have placed on you) so that anyone can read what you've written and understood it. You should strive to be specific and complete in responding to the questions. Your answers should be analytic, thoughtful and insightful, and should provide an insightful connection between ideas. The writing should be tight and crisp with varied sentence structure and a serious, professional tone.
The importance of water in the Critical Zone cannot be overstated. Water plays a primary role in physical and chemical weathering, erosion and transportation of sediments and dissolved ions, and the sustenance of life, to name a few processes. You should understand the water cycle and the various reservoirs in which water is stored and transported through the Critical Zone. You should also understand basic concepts linking water flow to the natural chemistry of water, and human influences on water resources. Finally, you should be confident in your ability to access widely available river and stream gauge data and should have used this data to learn about the surface water characteristics of your study site.
Here are some links to some Teacher's Domain resources (developed by Penn State!) that you might even want to use in your own classrooms:
You have finished Lesson 6. Double-check the list of requirements on the Lesson 6 Overview page to make sure you have completed all of the activities listed there before beginning the next lesson.
If you have anything you'd like to comment on or add to, the lesson materials, feel free to share your thoughts with Tim. For example, what did you have the most trouble with in this lesson? Was there anything useful here that you'd like to try in your own classroom?
Links
[1] http://www.teachersdomain.org/resource/ess05.sci.ess.watcyc.lifeessential/
[2] http://www.earthscienceworld.org/images
[3] https://water.usgs.gov/edu/watercycle.html
[4] http://en.wikipedia.org/wiki/Precipitation_(meteorology)#Ways_of_precipitation
[5] http://en.wikipedia.org/wiki/Atmospheric_circulation
[6] https://www.quora.com/Why-are-deserts-dry
[7] http://en.wikipedia.org/wiki/Monsoon
[8] http://en.wikipedia.org/wiki/Cryosphere
[9] http://earthobservatory.nasa.gov/Features/Water/
[10] http://www.epa.gov/safewater/kids/flash/flash_watercycle.html
[11] http://www.epa.gov/safewater/kids/
[12] http://www.teachersdomain.org/resource/ess05.sci.ess.watcyc.lp_watercycle/
[13] https://www.nsf.gov/news/news_summ.jsp?cntn_id=191016
[14] http://wikiwatershed.org/
[15] http://pubs.usgs.gov/wsp/wsp2254/
[16] http://en.wikipedia.org/wiki/Water_resources
[17] http://extension.usu.edu/waterquality/
[18] https://waterdata.usgs.gov/nwis
[19] http://water.usgs.gov/osw/streamstats/
[20] https://www.pbslearningmedia.org/resource/watsol.sci.ess.water.amdren/acid-mine-drainage-remediation/
[21] https://www.pbslearningmedia.org/resource/btl10.ela.early.itsaph/its-a-p-h/