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(Activities and demonstrations are in italics)

• Purpose
• Objectives
• Introduction
• Water: the marvelous molecule
• Electrolysis of Water
• Availability of Water
• Physical Properties of Water
• Changes of State Demonstration
• The Water Cycle
• Rio Grande Watershed
• Delineation of Rio Grande Watershed
• Analyzing River Flow Graphs
• Calculating River Flow: a field trip activity
• Environmental Impact of Dams and Channelization
• Population Pressures on the Environment
• Residential Water Conservation: a month long homework assignment
• Origin of Rock
• Continental Rise: an analogy
• Formation of the Aquifer and Rio Grande Rift
• The Intercontinental Separation: a demonstration
• Charging the Aquifer
• Impact of the City Upon the Aquifer
• City Planning: a new concept
• Final Project: Water is Infinite, Albuquerque is finite
• Summary
• Notes
• Materials
• Bibliography
• Student Reading

The purpose of this unit is to understand the water cycle. Students should understand where our water ultimately comes from, how it gets here, and its relationship with the environment once it arrives. The effects we shall examine are the erosion it causes, the growth it nourishes, and the rivers and aquifers it fills. In addition, we will study the effect that our human culture has upon the Rio Grande and the aquifer that underlies it. In order to understand the effects, we will study the geologic history and development of the aquifers and the surrounding rock formation.

Students will be able to

• draw a diagram showing the water cycle
• delineate the boundaries of a watershed
• compute an approximate measure of how much water is provided by a watershed
• graph and analyze river flow data
• draw a cross section of the Rio Grande Rift
• identify rock types and give characteristics of each
• calculate specific gravities of rock types
• diagram main features of an aquifer
• identify how water is used and/or wasted by Albuquerque’s Human Population
• Create a legislative plan or city policy to conserve water
• Individually practice water conservation

I teach at Rio Grande High School, which is situated in the Rio Grande Valley, about a mile from the Rio Grande. The student population comes from both an urban and rural background. Many students live on land that is irrigated by the acequias that tap the waters of the Rio Grande. All of us are dependent on the aquifer for our domestic water supply.

Albuquerque receives little rainfall, about 7-10 inches annually, and depends upon the higher mountains to the north of us to capture atmospheric water, tributaries of the Rio Grande to deliver it to us, and the aquifer to hold it in deposit so as to permit us to withdraw it as needed. However, there is a finite flow of water provided by the mountains. As the population dependent upon that supply has increased beyond the annual discharge of the northern Rio Grande, we have begun to deplete the aquifer that has been collecting water for thousands of years. Sooner or later, our inheritance will vanish. We see some consequences of a depleted aquifer today. As the aquifer is drawn down, water from the river channel percolates down to refill the unsaturated alluvium. At certain times and in certain areas, the river’s flow is so small, and the percolation so great, that the Rio Grande runs dry. This should and, at least partially, has served as a wake-up call to cities in the Rio Grande Basin.

The population of Albuquerque exploded after the Second World War, and is continuing to expand. As with all southwestern cities, Albuquerque is beginning to examine water issues. The city council recently began entertaining legislative ideas to

conserve water, such as not permitting watering of lawns between 10:00 a.m. and

6:00 p.m. We have water cops who issue tickets to flagrant water wasters. But still we generally live in a state of desert denial. The new county Court House has a vast, lush lawn, and an almost invisible xeric garden. A woman in a city subdivision attempted to replace her midwestern, water thirsty lawn with xeric landscaping and was blocked in that attempt by the subdivision’s board. Eventually, she did prevail, but only after public opinion scorned the idiocy of a policy that mandated water waste.

We see water waste every day; malfunctioning sprinklers misdirecting or geysering water straight up and out into the streets, lawns being watered during windstorms, or during the hottest time of the day, or consequently relying on automatic sprinklers to water during a heavy rainfall. Ironically, the water wasters are too often our government and our schools, the very institutions that preach and teach water conservation. The schools should not only educate but also model, and students should have the tools to observe wasteful practices and call the appropriate villains on their wasteful sins. Likewise, by studying the wasteful ways of our society, we will become aware of our own methods of utilizing water, and recognize our own individual sins. Too often we blame the nameless corporations for the depletion and contamination of our resources as we drain our radiator’s antifreeze into the streets and leave the water running as we brush our teeth.

Water is undervalued and unappreciated in those regions of the world where it has become too easy to obtain. By marveling at the life-giving characteristics of water, and its importance and scarcity in our environment, students should take away from the unit a sense of wonder at just how unique our planet might be, and perhaps a sense of responsibility that we are, in however small a part, her guardians.

We live on a water planet, though precious little of it is available at any one time to nourish the quarter of the planet that is terrestrial. Many factors contribute to the liquid state of water and its distribution. The earth rotates on its axis every 24 hours. This rotational time period keeps the different regions of the earth from overheating and freezing. Likewise, its distance from the sun and our atmosphere provide a temperature range in which H₂O exists primarily as a liquid. We presently have not found any other planet or moon in our solar system where water exists as a liquid, although Mars does show a past history of water flow.¹

But the earth also has regions that seasonally cool enough that the water will cool to a solid. This occurs most often at high latitudes and altitudes. It is the high altitude mountains in northern New Mexico and southern Colorado that form the watershed for the Rio Grande. The snows that fall there in the winter form a snowpack, a reservoir of H₂O. A large fraction of that snowpack will gradually melt, run off, and provide the lowlands with water during the warm summer months, thus serving as a time capsule for water transport to the desert environments.

Aquifers serve as even better time capsules. The material in the aquifers slows the water to a crawl, and serves to preserve water for decades and even centuries into the future.

A water molecule consists of two atoms of hydrogen and one of oxygen. Chemically, it is expressed as H₂O. We can show this recipe by setting up the following demonstration.

This demonstration should be set up at least one hour prior to class to allow enough gas to collect to provide the "oomph" of the experiment.

Bubbles will immediately begin to collect at the exposed electrodes in the test tubes. One test tube will accumulate gas at twice the rate of the other tube. One can question the students as to which test tube contains oxygen and which contains hydrogen. Have the students examine the charges on each of the collecting rods, and remind them that opposites attract. Given that information, query them as to which part of the molecule carries a positive charge and which carries a negative charge.

Finally ask students to guess what would happen if one were to put a match in each of the test tubes.

2 H₂ + O₂ > 2 H₂O + energy.

This demonstration perks the students up quite a bit. Always there are requests to do it again, even amidst complaints that it wasn’t a very impressive explosion. (‘Tis sad we need explosions to spark youthful curiosity, but we do what we must).

This simple molecule occurs in abundance on Earth. However, it is not spread out evenly, and much of it is not usable in the places that it does occur. The oceans contain 97% of the water on this planet and 2.7% is locked up in glacial ice. Only 0.3% of the planet’s water is liquid fresh water. This is distributed in lake, rivers, groundwater, and atmospheric water vapor.²

Fresh groundwater holds 0.76% of the planet’s water, and only 0.0002% of water is in our planet’s rivers at any one time. Soil water and lakes contribute another 0.014% water. Thus, prior to the invention of the windmill and the water pump, terrestrial life on this planet had to make do on about 0.02% of our planet’s water. It is simply amazing to this author that the Earth could do so much with so little in the middle of so much.

Water does not behave like most substances. Unlike most substances, water expands when it freezes, and thus decreases its density. This decreased density allows it to float to the top of the remaining H₂O occurring in the liquid state. This ice cap insulates the body of liquid water. Much energy is required to transform H₂O from its solid state to its liquid state.

Prior to class, place similar containers of olive oil and water in a freezer and allow them time to solidify. Although olive oil will solidify in a freezer, it is important that they begin their change of state at the same temperature. Although both substances start thawing at the same temperature, and although olive oil liquefies at an even higher temperature than water, the olive oil will liquefy much faster. One can also see that olive oil solidifies from the bottom up, while H₂O solidifies (freezes) from the top down. In addition to forming an insulating layer of air trapped between the ice and the liquid water, it exposes the ice to the spring sun so that it warms up first and then melts. It is this phenomenon that keeps lakes and northern oceans from freezing solid, something they would do if water behaved like other liquids.

It also requires a lot of energy to freeze H₂O. The latent heat of fusion for H₂O

is 80 calories/gram. This means that it takes as much energy to freeze a single gram of water as it does to lower the temperature of 80 grams of water by 1^o Celsius. (A calorie is the energy required to raise the temperature of one gram of water by 1^o C. A food calorie is actually a kilocalorie or 1000 calories). It takes an equal amount to liquefy water from snow or ice.

Likewise, water has a high "latent heat of vaporization". This is the amount of energy required to change water from its liquid state to water vapor. At 35^o C., a warm summer day (95^o F.), it requires 580 calories to evaporate a single gram of water. To you and I this means that one-gram of sweat cools 580 grams of water (slightly more in body mass) by 1^o C. In familiar terms, a teaspoon of sweat will cool 12 pounds of body mass by 1^o F., lucky for us.

Water will fall as snow when the temperature approaches 32^o F., something that frequently occurs in the southwestern mountains. That the temperature range of the earth’s climate allows H₂O to fall as snow, and thus accumulate during the winter, is vastly important to the arid southwest.

The earth’s surface is three quarters water. This affects the earth’s climate in several factors. First, water is a wonderful heat sink. As mentioned earlier, it takes a lot of energy to heat water. You notice this every time you go to a swimming pool or the beach on a hot summer day. The sand or the pavement leading to the water is almost unendurably hot, but the water is deliciously cool. This characteristic serves to moderate the temperature of the earth. It is because Seattle, New York City, and much of Europe are near large bodies of water that they have mild winters, though they are located in the northern latitudes.

The same atmosphere that captures and retains the solar heat also plays a vital role in the transportation and distribution from the oceans to the land.³ The vast oceans provide a lot of surface area for water to evaporate into the atmosphere. Air is evaporated from the oceans, and is carried by the winds to the continents. The forces behind the winds are the temperature gradient between the polar regions, and the rotation of the earth from west to east. The winds carry this water-laden air over the landforms. Warm air holds lots of water, cool air less. For every 1000’ that air rises, it cools off 3.6^o F. The San Juan Mountains rise to heights of more than 14,000’. Wheeler Peak in the Sangre de Cristos rises to over 13,000’. As the air hits these barriers, it is forced to rise. As it rises, it cools. If the air is saturated with water vapor, it must rid itself of this as it cools. In the winter, this precipitates out as snow. It is this characteristic that allows water to be stored in the mountains, and then released in the spring and early summer when plants and agricultural societies can use it to grow and irrigate plants, as well as to quench our thirst. The latent heat of vaporization and latent heat of fusion also moderate or slow down the rate at which snow melts or sublimates (passes directly from solid to vapor), and thus serves to create the aforementioned "time capsule" of water flow.

When water falls, it takes a variety of paths. Initially, much of it will percolate into the soil, where it will be bound to the soil or travel down into the aquifer. Plants will absorb this water through their root systems and transpire it or incorporate it, along with CO₂ into carbohydrates. When the soil become saturated, it will form rivulets (runoff) and flow into arroyos, creeks or gullies. Water in the creeks and arroyos will obey Newton, forming tributaries to ever larger bodies of water, such as rivers or lakes. Roots, humus or organic matter, and vegetation, slow the water’s velocity and hold the soil in place. Disturbances to the plant community increase erosion and add to the siltation of the rivers and reservoirs. In times of flooding, the rivers will overflow their channels and deposit material that they have carried from the uplands. In the past, this flooding has rebuilt and revitalized the fertile floodplain soils, simultaneously adding material to the underlying aquifer.

The Rio Grande does indeed have a deep aquifer underlying it. It was the Rio Grande and ancient rivers that created this aquifer, carrying loose eroded material from the highlands, and depositing it in its channel. Before the Cochiti Dam was built, the Rio Grande had to be dredged to allow the river clearance to flow. At times, the bottom of the Alameda Bridge was but a meter above the riverbed. The Rio Puerco, which remains undammed, is responsible for half of the sedimentation of Elephant Butte Reservoir, though it contributes only 6% of the water flow. ⁴ The dams have not stopped erosion. They have merely changed the depository of the sediment. We still have alluvial fans flowing from the canyons. But flood plains have been replaced by alluvial lakes that underlie all the great reservoirs of the world. As of 1987, Elephant Butte Reservoir had 20% of its storage capacity replaced by siltation, the process by which river water deposits its load of sediment when its energy is stopped by the still backwaters of a reservoir.⁵

Today, the Rio Grande, along with a myriad of other western rivers has been leveed, channelized and dammed. These developments have led to changes in the riparian communities downstream. We shall examine these changes later.

The Rio Grande drains a huge amount of real estate, much of it snow capped mountains that lay upstream of Albuquerque. It is this drainage, and the chemical properties of water, that have permitted societies to live in the arid Rio Grande Valley for a millenia.

2. Provide forest service maps of the Four Corners area, Gunnison Basin Area and Carson National Forest.⁶ Have students delineate the boundaries of the Rio Grande and Colorado River drainages. Also use this as an opportunity to explain the Continental Divide.

Data for river flows of the Rio Grande Basin in New Mexico can be accessed at the Adobe Whitewater Club website "http://www.thuntek.net/~trobey/awc.html". This site gives daily flow rates, and also displays graphs that show flows for the past week.^7,8

The river flows will dramatically show how dams affect the flow. A free flowing river shows gentler shifts in flow increases and decreases. The data for June 2 to June 8, 1999 show that the Rio Chama is flowing at about half its average flow for this time of year, while the Rio Grande is near average (above dam sites). This would lead one to believe that the Rio Chama drainage has a much smaller snowpack. But why is the Rio Grande near normal when the snowpack is less than normal? Students should be asked to hypothesize why this contrariness is being displayed. The snowmelt depends on both the surface area covered by snow, the saturation of the soils, and the temperatures. Perhaps the mountains had temperatures a bit above normal, and although the depth of the snowpack was small, the surface covered by snow could be near normal. If this is the case, because the snowpack is shallower, one would expect the river flow to decrease below average much more rapidly as the summer progresses.

If we look at river flow data below dam sites, we see something quite different.⁹ The Rio Chama below Abiquiu Dam has sharp, distinct drops as floodgates are partially closed. These changes in the river flow occur at the same time each day. The flow at times is 60% greater than normal, and four days later is about 25% below normal. This is not due to any weather events, but is caused by a human pushing a button that turns a wheel that opens or closes the floodgates.

The same situation can be observed by comparing data from the Rio Grande as it comes out of the Rio Grande Gorge at Taos Junction Bridge to the Rio Grande below Cochiti Dam. It would also be beneficial to analyze data of the Rio Grande at Albuquerque, several miles downstream from Cochiti, to show how irrigation diversions affect the river flow.

Calculating River Flow: A field trip activity

River flow is measured in cfs (cubic feet per second). By drawing a cross section of the river and measuring its current, we can calculate the flow of a river. Albuquerque has several pedestrian friendly bridges over the Rio Grande. Bridges at Central and at Montano would provide good measuring sites for this exercise.

1. Construct a cross-section of the river. Use a weighted line to measure the depth of the river at 5 foot intervals, using the bridge as a transect. Plot this information on graph paper (one grid = one foot). Students can connect the dots and count the grids the river occupies, thus estimating its cross-sectional area. To aid in this investigation, I would suggest placing different colored ribbons at one-foot intervals on the weighted line.

2. Measure the river current. The river current is not uniform. It is slower at the margins and above shallow sandbars, where the drag is large, and swifter in the main channel. A simple measure would be to drop a stick in the main channel and measure its distance traveled in 10 seconds and divide to get speed in feet/second. Multiply this by the cross-sectional area to obtain a crude estimate of cfs. A better measure would be to divide the river into sections and measure the current in each section. Calculate the cfs for each section, and sum the sections.

How has channelization and damming of the Rio Grande affected the riparian community? Three trees dominate the Rio Grande bosque: the indigenous cottonwood, the exotic tamarisk with its pink flowers, and the sweet smelling Russian Olive. If you observe the cottonwood orchards, you will notice they are all of the same height throughout the entire length of the bosque. This would indicate a similar age. Cottonwoods live in a seemingly dry desert because they have tapped into the water table. In order for the tap root to reach the water table, it must have a time period where the soil above the water table is saturated with water. If the young root can then outrace the drying out of the upper level of soil moisture, it will have a permanent source of water. If it loses the race, it loses its life.

Floods were the source of this water saturation of soils in the bosque. By observing when cottonwoods release their seeds, the natural time of periodic flooding can be determined. Evolutionarily thinking, those cottonwoods that cast their seeds to the wind at the precise time that floods generally occurred would perpetuate their flood-timed genes in the gene pool. Those whose timing was somewhat flawed would have their genes removed from the population. Floods occur when today’s cottonwoods bloom. Rio Grande cottonwoods release their bloom in early June.

But dams have stopped the floods. The cottonwood orchards in Albuquerque date to 1941, the last year the river overflowed its levees and flooded Albuquerque. By 1957, the river had been thoroughly channelized. Cochiti Dam was completed in 1975.¹⁰ Barring some severe catastrophe I don’t even dare to contemplate, the Rio Grande will not flood in our lifetimes. This "benefit" to us, however, spells the doom of the cottonwood forests. Cottonwoods have a maximum life of about 130 years.¹¹ Thus, in 70 years, this rare cottonwood ecosystem may very well be history.

In order to thwart this prognosis, attempts are being made to establish young orchards of cottonwoods. If one strolls through the bosque, young cottonwoods can be seen uniformly spaced in clearings. A hole is augured through the soil to reach the water table, and a mature sapling is then placed in this hole. With its root immediately placed in the water table, it need not wait for the flood that will never come. This is an admirable attempt at restoring a healthy natural community in the bosque, but it is flawed. Cottonwoods set out billions of seeds each spring, and only those seeds that found prime spots, and had suitably adapted genes, would survive. We have decreased the gene pool, decreased the numbers of trial and error growing sites, and undone the evolutionary process.

In addition to undoing the natural cycle of the bosque, we have introduced exotic species into the bosque that dramatically change environment. Two introduced trees to the bosque are the Russian Olive and the Tamarisk or Salt Cedar. These trees grow extremely dense stands, and change the environment around them to exclude new growth by other species. As a result, dense thickets of salt cedar and Russian Olive are increasing their habitat at the expense of the open, aging, Cottonwood orchards.

Humans have lived in the Rio Grande Valley for thousands of years, but attitudes towards water and weather have not always been comparable. Weather forecasters today describe cloudless warm days as beautiful, and use "ugly" to describe days of lingering, cold rain. We live in a culture that contrarily worships ample sun, lush greenery, and water without rain. Nancy Griffith writes in "Trouble in the Field" about today’s young people who "never want the rain to fall, or the weather to get colder," because we are removed from the environment that is healed by the rains and rejuvenated by the winter. Because we turn a knob clockwise, and water flows effortlessly until we turn the knob counterclockwise, water is unappreciated and undervalued. It was not always so.

A visit to Kuau, a pueblo located on the banks of the Rio Grande in what is today Bernalillo, allows one to contemplate factors which were taken into account to determine settlement sites. Standing in the coolness provided by the sunken Kiva, one also comes to appreciate the reverence that the former residents bestowed on water. The wall of the Kiva is a circular series of murals. Streams of black dots fan out from the mouths of bird and human figures. My first impression was that the stream represents an energy source flowing either into or from the creatures. The explanation given by caption in the mural museum is that the expanding streams represent rain. And then I realize, perhaps wrongly, but it suits my psyche, that the artists believed rain to be the force responsible for the essence of life and of the soul.

Water signs are represented in almost every mural in the Kiva. Lightning bolts energize ollas, or water jugs. Clouds are formed into altars. The same form of water drops fanning out from mouths of living creatures also flow from painted pots. Outside we were given audio evidence of the reverence for water, music for a cloud dance, as we looked over the Rio Grande and the green ribbon of cottonwoods that ran along either bank.

Earlier inhabitants of the southwestern deserts lived in semi-permanent communities such as Kuau. They would settle by a water source, and live off the resources until they had depleted the neighboring land of firewood and game, and exhausted the soils of their nutrients and made their croplands saline with irrigation. They might live a few generations at one site before abandoning it for another watershed. In time, the land they had left would be rejuvenated by fresh growth, animal reproduction and migration. The river would flood, settling rich dirt upon the flood plains, junipers and pinons would once again grow to such a size as to provide firewood opportunities, and eventually, the people could rotate back onto its land.

Today, settlements are permanent. The lifestyles, property laws, and the sheer numbers of our society do not permit abandoning homes, much less, entire cities, every few generations. Today, we still deplete the soil, but rely on chemical fertilizers to provide the nutrients. We build homes in the flood plain, and then dam and channelize the river so as to protect our homes. The consequence of this action is that no new soil is added. In fact, our farming practices speed up wind and soil erosion so that our soil is disappearing, adding beauty, perhaps to the sunsets, but depriving our domestic plants of substance.

Also, our predecessors carried all their water. The practice of carrying water is a great teacher of water conservation. I have in the past lived in homes with no indoor plumbing. We carried our water from the city in 5-gallon containers. We cooked, drank, washed dishes, and sponge bathed with this water. (I must also admit that we took showers at the swimming pool and at friend’s homes). We made do on no more than 50 gallons/week. Contrast this to the average American today who uses 188 gallons/day, or even the much praised citizens of Tucson, who are revered for using only 105 gallons/day (a feat I actually do applaud). This use includes residential use, lawn and garden irrigation, and flushing the toilet. One flush of an inefficient toilet equals the amount of water I used in one day.

Because our predecessors carried their water, it was to their advantage to develop efficient uses of water. They planted crops native to the region for basically one reason: they had no choice. But the benefit of having their seed pool limited to native plants was that these plants had evolved and adapted water saving methods. Desert plants have evolved several strategies to conserve water: small leaves, succulent leaves, no leaves, leaves that grow quickly after a rain (ocotillo). They have also developed efficient methods of gas exchange (breathing) that serve to conserve water. Corn is a C₄ plant, so named because it absorbs CO₂ initially in a four-carbon chain, in contrast to a three-carbon chain that most plants utilize.¹² C₄ plants use water 50 to 300% more efficiently than C₃ plants. Cacti use an even more water efficient method of gas exchange by "breathing" at night when humidity is higher, and storing it until it can be utilized during the day. CAM plants, as these are called, are seven to 18 times more efficient than C₃ plants.

In addition to choosing water-conserving plants, they developed water efficient irrigation methods. The Zuni waffle garden sinks small foot square plots into the ground. Each plant receives its own dose of water, and each section of soil is less exposed to the drying sun than the soil around it.

Today’s farmers practice flood irrigation on water loving crops that are planted in furrows that are highly exposed to the sun. They take their water allotment when it is available, whether they need it or not. Agriculture is the largest user of water in the region.

In addition, the local communities have used water, our most limited resource (along with tax credits), to lure high water use industries such as computer chip makers (Intel) and dairy farms to settle here. Settle here, that is, until the water becomes appropriately valued or scarce, at which time, Intel and the other industries will revert to the ways of the pueblos and migrate to another watershed or tax base.

While city residents do not waste water on the massive scale that agriculture and certain other industries do, they (we) do not give it the reverence it deserves. The task, then, in this day and age when the average person feels so insignificant that they feel whatever one person does is useless, is to create an attitude that values water, and thus conserves it. We need to create a society that doesn’t water in the middle of a rainstorm, nor use water as a broom, to wash away dirt from their driveway (and move it to the next driveway or curbside downstream or downstreet).

Water is too marvelous a substance to be underappreciated. We can survive without cars and gasoline, without television and malls, and without the pollution which they all contribute to. We can not survive without water. The following exercise is designed to instill an appreciation of water and value its conservation.

4. The challenge, for extra credit, would be to reduce per capita use of water by 7% for 25 extra credit points, 12% would receive 50 extra credit points. Evaluation would be examination of monthly water bills. Students could earn these extra credit points any month of the school year. I would rationalize these additional points by the belief that this exercise is a better application of long lasting knowledge than a test listing ways in which water can be conserved.

Alternative: Many of my students live in apartments that do not have separate water meters. So as to not exclude them, I would have them identify areas of water waste around the school, or around the city, and have them write a letter to the principal, the mayor, or other appropriate person-in-charge, identifying the problem, suggesting solutions to the problem, and stating their opinion as to why this problem should be fixed.

The students will have several types of rocks on their table: quartzite, granite, basalt, limestone, and pumice. When asked to investigate the differences between rocks, students will remark on the patterns evident in the metamorphic quartzite, the crystals in the granite, the gray color and fossil presence in the limestone, the air holes and lightness of pumice, and the black color of the basalt. These observations are all evidence of the origins of these rocks.

Students will conduct a lab to determine the specific gravities of these rocks. In order to do this, they will need to determine the volume of a rock sample. Demonstrate displacement of water by dropping solids (coins) into a graduated cylinder and calculating their volume by the amount water rises in the tube.

Large rocks present a problem in that they don’t fit into a graduated cylinder. Guide students through process by which rock volume can be determined:

6. Calculate density: density = mass (grams)/volume (milliliters).

Students will determine specific densities for three types of igneous rocks; granite, basalt, and pumice. The lab data should show that basalt is denser than granite. The asthenosphere is partially melted and plastic¹³, and is thus influenced by the density of the plates that rest above it. Since basalt is denser than granite, oceanic basalt "floats" lower than the granitic continental plates.

Continental Rise: an analogy

A demonstration to show the differing altitudes of basaltic plates and granitic plates could be performed using a basin of water, a dense hardwood, and a less dense pine wood of identical thicknesses.

The water represents the asthenosphere; the hardwood, the basalt: and the pine represents the granite. Placing them in a basin of water illustrates that the granitic pine "floats" higher than the basaltic hardwood. This illustrates the continents (pine), composed of lighter granite, floating higher on the asthenosphere than the denser basalt (ironwood), that forms the oceans’ floors.

From the balcony outside my second story science classroom, I have a wonderful view of the Rio Grande Rift. It serves as a wonderful backdrop to a lecture and discussion on the formation of the present day landscape. A collection of rocks sits on the table at the edge of the balcony. Beyond the rocks, the students gaze at the Sandia Mountains, easily visible to the east, the valley floor directly north of us, and five volcanic cones that dot the horizon created by the West Mesa.

The collection of rocks that rest on the table include: gray, fossil-bearing limestone; pink, crystallized granite; black basalt; white, light pumice; pummeled alluvial representing eroded granite; sand collected from the Sandia foothills; and several sea shells. Also on the table are a magnet and a bottle of dilute HCl (Hydrochloric acid).

Students are asked where in the landscape they could find the rocks that are resting on the table. Basalt can be found on the West Mesa, granite forms the lower pinkish rock of the Sandias, and limestone can be found capping the Sandia Mountains. The gravel washes down from the mountains and can be found on the lower slopes of the Sandias, and sand is found in the arroyos.

To illustrate the origin of limestone, a drop of HCl is dropped on the seashells, and then onto the four rocks. Only one rock shows the same "fizz" that the seashells display. From this, students will deduce that seashells (or something like them) must have formed the limestone layer. Fossils that are found in the limestone give further evidence to its seafloor origin. But how did an ocean form at the top of mountains?

Using an Aquarium as a container, a fault block is demonstrated. Two sloping wooden blocks, representing the diverging fault.¹⁴ Three 3/4" layers of flour, each layer a different color to represent a different strata, are placed on top of the blocks. The teacher separates the wooden blocks. The energy that causes the separation comes from mantle convection. As one of the blocks is pulled away, the flour falls and becomes thinner, paralleling what has happened over the 25 million years the rift has been separating.

Twenty-five to thirty million years ago, the continent cracked and began to move apart. This separation created a rift that extends from central Colorado to northern Mexico. As the rift separated, the material in the rift zone dropped and spread itself thin to cover the enlarged area created by the rift. At the same time, the eastern section of the plate was uplifted. Thus the Sandia Mountains are capped by limestone at a height of 10,000 feet. The same strata of limestone dropped as the rift separated and can be found 15,000 feet below sea level. Further west, below the Rio Puerco, Pennsylvanean limestone is approximately 4000 feet below sea level. The volcanic cones are also a result of the continental plate separating. Magma is the source for the basalt, and lies below the continental plate. As the plate separates, fissures are created that form conduits that allow the magma to travel to the top of the plate and form volcanic cones. As the strata is the rift dropped, loose eroded material (alluvium) from the Sandia Mountains, and northern mountains (the Jemez, Sangre de Cristos, and San Juans) filled in the rift. This loose alluvium has formed the aquifer that now underlies the Albuquerque basin.

Give students a handout showing a cross section of the Rio Grande Rift. Have students color the granite strata pink (this granite was formed 1.4 Ga (billion years ago). Next students will color the limestone strata, noting that it is nearly the same thickness in all three zones. This limestone layer is approximately 300 million years old. This billion year unconformity was caused by erosional processes that occurred as overlaying rock was stripped away, exposing the granite, and then a sea forming and harboring the life that died and formed a cemetery of sea shells and diatoms that eventually created the limestone strata. Have students color in the other strata that overlay the Pennsylvanean limestone. They will note that the strata to the west of the rift and in the rift zone are approximately the same thickness and display qualities of sedimentary formation. These strata are absent in the Sandia Mountains, illustrating erosional processes that stripped them of these subsequent strata. The ducts that extend from the volcanic cones are shown unbroken. This is evidence of recent formation of the volcanic cones.

The headwaters of the Rio Grande begin in the San Juan Mountains, below Snidom Peak (elevation 14,084 feet). The Continental Divide runs through the San Juan Mountains. Runoff from the western slopes of the San Juans will flow into the San Juan and Animas Rivers, tributaries to the Colorado River. Water on the eastern slopes of the San Juans form the Rio Grande, which flows eastward through southern Colorado, dropping quickly until it reaches Alamosa, Colorado, in the San Luis Valley. At this point, it bends southward and follows the fault-bound valley of the Rio Grande Rift. The Rio Grande also collects water from the Sangre de Cristos and the Jemez Mountains. As the river flows through its channel, its waters percolate into the loose material that lies under it, until the material is saturated. Thus, the aquifer depends not so much on Albuquerque’s climate as it does on the precipitation that falls on the northern mountains in a process described earlier in the paper.

This process started millions of years before habitation by humans. Early human residents relied only on surface water, or on water near enough the surface to be accessed by shallow wells. Thus the aquifer remained fully saturated (charged). Technology provided a means to tap into this aquifer with water pumps. This technology has allowed populations to live in areas with no surface water, and to expand beyond population limits previously allowed by limited surface water.

Presently, Albuquerque is using more water than can be recharged by the Rio Grande, living beyond our means. As we draw groundwater from the aquifer, the upper alluvium, or aquifer, becomes unsaturated. The Rio Grande then percolates downward. At the same time, dams and irrigation diversions lessen the flow of the Rio Grande. At times, these factors are enough to dry up the Rio Grande between Albuquerque and Socorro. Species that depend upon the river for their existence are threatened. The Rio Grande Silver Minnow can not live out of water. The willow flycatcher nests in the willow trees that are dependent upon the river. As the willows die, the flycatcher loses habitat, and eventually passes into history. ¹⁵

Agriculture accounts for much of the water usage in the Albuquerque Area. Although much of the water used in irrigation comes not from the aquifer, but directly from the river channel, its removal depletes water that may recharge the aquifer, or keep the river’s volume adequate to sustain the riparian community.

Industry also competes for water use. Computer chip industries utilize much water for sanitation processes. Intel is a major employer in the area, and has much political power derived from its economic role.

As people immigrated to Albuquerque from more moist environs, they recreated, on their single home plots, the lawns they had grown up with. These plots used grasses that had evolved in areas where water was not the limiting factor. The desert has grasses that evolved where water was limiting, and adapted by evolving methods that conserved water.

Cities also demand neighborhood parks and golf courses, which generally have huge expanses of barefoot friendly grasses.

This is an exercise I have done in the past, adapted from "Project Learning". Each group of five students is given a section of butcher paper. They draw a landscape that reflects the Albuquerque environment. The Rio Grande runs from north to south and bisects the flood plain. An escarpment to the west defines the western limit of the flood plain. The eastern slope is defined by a series of benches, increasing in elevation to the foothills of the Sandias. Students are to then construct a semi-autonomous city upon this landscape. They must decide where to put farmlands, dairies, industries, a power plant, neighborhoods and parks, a wastewater treatment plant, and, yes, they must provide a place for schools.

Although we have a limited supply of life-giving water in our aquifers and flowing in the Rio Grande, that flow will continue long after Albuquerque has been abandoned. Our water supply, and along with that supply, the city of Albuquerque is finite, but time is infinite. Hopefully, Albuquerque will not be too finite, but its destiny rests in the hands of our predecessors, today’s residents, and the planning for and by the residents of tomorrow.

The group will then either vote or reach by consensus upon a plan to be implemented by the city. The mayor will preside over the meeting, and be responsible for drafting the final plan.

During the short course of this seminar, the local newspapers have had front page stories that address the conflicting pressures being placed upon the Rio Grande and its underlying aquifer. The Cottonwood bosque that exists for approximately 150 miles north and south of Albuquerque is a rare biome, but according to a recently completed report, will die if we do not radically change water use patterns. The recommendations were so daunting to officials of Department of Fish and Wildlife, the Army Corp of Engineers, and the Bureau of Reclamation, that they have ordered a new version of the report.

Symptoms of the River’s ill health are the decreasing populations of the Rio Grande silver minnow and the willow flycatcher. Biologists studying the bosque system have recommended, in part: spring flooding that mimic the natural cycle of the river and allow cottonwoods to reseed themselves, and trigger spawning instincts in the silver minnow; widening of the flood plain by moving levees away from the river; and limiting water storage in Elephant Butte Reservoir to keep it from flooding willow stands.

The Colorado River, which is fed by the opposite slope of the San Juans as the Rio Grande, is already a dead river. It dies many miles before it reaches the Gulf of California, and while not paralleling the natural environs, its cadaver should frighten us enough to seek to heal the disease of overdrafting the Rio Grande.

This curriculum unit, in a too short 3-week period, is being designed to give students a sense of the physical and chemical properties of water that permit it to create and host life; identify and appreciate the adaptations and strategies that plants have evolved to sustain themselves in a land of little water; understand human impact upon the aquifer and the Rio Grande riparian community; and finally, to develop the skills and a knowledge of the need to do something about it.

1. Merritts has a good graphic illustration on p. 44 of how temperature and atmospheric pressure affects state of H₂O. The earth is the only planet in the solar system that lies in the liquid water phase of the graph.

2. Also on p. 44 in Merritts are facts and figures of how water is distributed in the hydrosphere.

3. Chapter 2 of Young’s Sowing the Wind gives an easy to read explanation of how and why winds move, and the discovery of the jet stream by the Japanese in WWII and their application of that knowledge.

4. A photo of this is shown on p. 437 in Water in New Mexico, Clark, 1987. A photo on p. 280 shows a wide arroyo of the Rio Puerco.

5. For a list of diminishing capacities in western reservoirs, see pp. 491-2, Cadillac Desert.

6. Gunnison Basin Area Map shows Rio Grande Drainage in the San Juan Mountains. Carson National Forest Map shows Rio Grande Drainage of the lower San Juans in New Mexico and the Sangre de Cristos in northern New Mexico.

7. The Adobe Whitewater Club maintains a website at "http://www.thuntek.net/~trobey/awc.html" that shows weekly river flow information in graphic form, and compares it to average flows for the same time period. Whitewater clubs in other locations might contain similar information for rivers of local interest. If not, contact USGS (U. S. Geologic Service) for information.

8. Verner has a fine illustration on pages 9 and 10, showing the tributaries to the Rio Grande in Colorado and New Mexico north of San Marcial. Page 72 graphs annual discharge of the Conejos River at Mogote, Colorado, and the Rio Grande at Del Norte, Colorado. The Conejos River is a free flowing river, has few diversions, and is therefore most representative of precipitation and drainage patterns of the Upper Rio Grande Basin. Although much of this text is highly technical, pages 88-93 provide useful information on precipitation patterns in the Rio Grande Watershed and is easy (well, easier) reading.

9. I used five gauging stations: Rio Chama at El Puente, Rio Chama below Abiqui Dam, Rio Grande at Taos Junction Bridge, Rio Grande below Cochiti, and Rio Grande at Albuquerque. This can be on ongoing activity throughout the year. On Thursday of each week, students could analyze the graphs and reflect on the weather conditions that week that caused the river fluctuations.

10. The Bosque Education Guide, p. 43, has a time line of historic flooding of the Rio Grande.

11. Molles, in Ecology, pp. 192-3 describes graphically the aging of the "most extensive cottonwood forests remaining in the southwestern United States" that are growing (or dying) in the Middle Rio Grande Basin in central New Mexico.

12. Molles, pp. 138-40, has fine illustrations that show the strategies and physiology used by plants to conserve water.

13. Merritts, pp. 38-9, has explanation and cross sections of earth to show differing chemical physical properties of the layers of the Earth.

14. Merritts, p. 105, has an illustration upon which could construct the rift model. Using a 2 x 6 x 12" pine board, make diagonal cuts to create 3 sections of board, the middle section a "V" shape. Cut and remove the lower 3" of the middle section so that it may drop as the edges separate.

15. See "The Dying River Needs Changes," Albuquerque Journal, June 27, 1999; pp. 1, 12-13.

Electrolysis demonstration:

2 electrodes, a 6-volt battery, Barium sulfate (a salt necessary for the flow of electrons: distilled water is an excellent insulator, and thus will not allow electrons to flow through it), two test tubes and matches. It will take at least a full hour to collect the gases necessary to make a satisfactory "pop!" to amaze and amuse your students, so start this early on, and come back to it during your lecture on "the wonders of water" to explore what is happening and why.

Changes of State Demonstration

Two identical transparent containers: one containing solid H₂O (otherwise known as ice) and one containing solidified olive oil (place in freezer so that the beginning temperature is the same. This demo can be done in the same class period as the electrolysis demonstration, and it is a slow process. One will see the olive oil melts rapidly and from the top down, ice much more slowly and from the bottom up.

Watersheds

Maps of Colorado and New Mexico, showing rivers and dams. Forest Service Maps of the Gunnison, San Juans, and Carson and Santa Fe National Forests (the Jemez Mountains are located in the Jemez. A topographic map of a region students will be visiting on a field trip would be beneficial in locating their place, understanding contour lines and topographic features, and identifying drainages.

A transparent grid done on a scale one grid equals a township (6 miles square or 36 square miles). The instructor could use this as a taking off point to explain how the lands were platted and ownership distributed in the old West.

River flows:

Weekly data, in graph form, is available from the Adobe Whitewater Club’s website "http://www.thuntek.net/~trobey/awc.html". I would suggest tapping into the website on late Wednesday or early Thursday, thereby maintaining a complete set of data. For instructors outside of the Rio Grande Drainage, I would suggest contacting your local whitewater club. Their websites are great sources for this information, because of the importance of up-to-the-minute flow data necessary for calculating decision to call in sick.

Rocks

People outside Albuquerque will have to find their own rocks. In Albuquerque:

• limestone from the east side of the Sandias - it’s quite easy to find rocks containing fossils
• granite from the eastern slope of the Sandias;
• while on the eastern slope, also contain some loose gravel and sand (magnetite can be extracted from the sand with a magnet)
• basalt from the Volcanoes area;
• pumice and metamorphic rocks can be found in the Rio Grande flood plain.

You will also need the following equipment (one per group)

• graduated cylinder
• beaker (large enough to hold rock sample
• triple beam balance (or some other scale accurate to 0.1 gram)

Density demo

• Two blocks of wood, one pine and one dense hardwood. They must be of identical thicknesses.
• A basin of water.

Intercontinental Separation: Rift Demonstration

• Aquarium
• Wood or glass backing
• 2 x 6 x 12" wood
• colored flour

The Bosque Education Guide: An Environmental Education Program to Teach About the Riparian Forest Within the Middle Rio Grande Valley. Albuquerque: U. S. Fish and Wildlife Services, October, 1995.

Clark, Ira G. Water in New Mexico: A History of Its Management and Use. Albuquerque: University of New Mexico Press, 1987.

Merritts, Dorothy; DeWet, Andrew; and Menking, Kirsten. Environmental Geology. New York: W. H. Freeman and Company, 1998.pp. 29-60, 102-119. Good text and excellent illustrations of the hydrologic cycle and plate tectonics.

Parfit, Michael. Sharing the Wealth of Water. National Geographic Special Edition. November, 1993. pp. 20-36.

Parfit, Michael. When Humans Harness Nature’s Forces. National Geographic Special Edition. November, 1993. pp. 56-65.

Reisner, Marc. Cadillac Desert. New York: Viking, 1986.

Verneer, Jetton Elden. Climatology of the Upper Rio Grande Basin and the Development of Spring Runoff Forecast Equations. Ann Arbor, Michigan: U M I Dissertation Services, 1973.

The River: A Seventh Grade Inter-disciplinary Curriculum for the Rio Grande. 110 Vuelta Montuoso; Santa Fe, New Mexico 87501 ( 505) 983-5428. Project Crossroads, circa 1993.

Rosner, Hy and Rosner, Joan. Albuquerque’s Environmental Story. Albuquerque: Albuquerque Public Schools, 1985.

Taugher, Mike. Report: Dying River Needs Changes. Albuquerque Journal. 119th year, no. 178. June 27, 1999. pp. A1, A12-13

Young, Louise B. Sowing the Wind. New York: Prentice Hall Press, 1990.

Cadillac Desert. Corporation for Public Broadcasting.

Nova Water Crises. Time Life.

Merritts, Dorothy; DeWet, Andrew; and Menking, Kirsten. Environmental Geology. New York: W. H. Freeman and Company, 1998.pp. 29-60, 102-119. Good text and excellent illustrations of the hydrologic cycle and plate tectonics.

Young, Louise B. Sowing the Wind. New York: Prentice Hall Press, 1990.