Landforms

One of the largest geographic physical structures in the United States is the Colorado River. Human activity and its interaction with this great river have an interesting history. The resources provided by the river have been used by humans, and caused conflict for human populations as well. One of these conflicts is water distribution, and the effects drought conditions have played in this distribution throughout the southwestern region. Major cities such as Las Vegas, Los Angeles, San Diego, and other communities in the southwest depend on the river. It provides water for over 20 million people, irrigation for 2 million acres of land, four thousand megawatts of hydroelectric energy, and over twenty million annual visitors for

The annual rate of precipitation, and elevational range once generated a strong foundation for a wide diversity of vegetation

Questions and charts are from Geoscience Laboratory, 5th ed. (p. 155–167), by T. Freeman, 2009, New York, NY: John Wiley & Sons. Reprinted with permission.

Exercise Lab 1. How much does temperature vary in large and small aquatic environments? Lab 2. What determines the water clarity of lakes, rivers and oceans? Lab 3. Where does the phosphorus go? Lab 4. How does human activity in watersheds affect the quality of lakes and rivers? Lab 5. Are the Great Lakes being influenced by the global greenhouse effect? Lab 6. How is the flow of the Red Cedar River influenced by the weather? Lab 7. What is the relationship between flow and turbidity in the Red Cedar River? Page 2 4 6 8 12 15 18

Arizona has an incredibly large dependence on the Colorado River and groundwater. In fact, 39% of all water usage in Arizona is comprised of Colorado River water. Any dependence of that scale on any resource that originates in another area is always a major risk, as any major disaster or drastic change to the source of the river can cripple the state’s water supply. Furthermore, while Arizona does house the majority of the Lower Basin of the Colorado, the Colorado’s Upper Basin is shared between 4 other states, all with their own water needs and all with a susceptibility to drought. On the other hand, another 40% of all water Arizona uses is from groundwater sources. However, the Colorado River and these groundwater sources in the Colorado River basins have lost over 65 cubic kilometers of water over the last 9 years, with nearly 2/3 of it from groundwater loss due to over-pumping. This is because

On average, the temperate deciduous woodland should receive around 750-1500mm of rain per year. If this number is greatly exceeded, then the soil will become saturated and the area will flood, suffocating the plants as they do not have access to sufficient oxygen and carbon dioxide. On the contrary, if there is not enough rainfall then the plants will also die because they do not have access to a plentiful supply of minerals that the water contains such as nitrogen and magnesium.

In his book, Cadillac Desert: The American West and Its Disappearing Water, Marc Reisner’s main thesis is to show the inefficiency, greed, and inherent difficulty in the American West’s never-ending struggle to turn its unwelcoming desert into a lush garden. One of his main sub-points is that the West is not meant to support millions of people. It has a wide range of geographic challenges throughout the entire region. Its inconsistency and diversity is a primary cause of its water problems. For example, Reisner notes that the West consists of “plains so arid that they could barely support bunchgrass; deserts that were fiercely hot and fiercely cold; streams that flooded a few weeks each year and went dry the rest; forests with trees so large it might take days to bring one down; . . . hail followed by drought followed by hail;” (23).

Heavy precipitation events that historically occurred once in 20 years are projected to occur as frequently as every 5 to 15 years by this late century. Short term droughts are expected to intensify in most regions. Longer term droughts are expected to intensify in larger regions in the Southwest. Flooding may intensify in many U.S regions. Climate change is affecting the groundwater availability also. Sea level rising and storms surges are expected to compromise the sustainability of coastal freshwater and

It is undeniable that climate change is drastically changing our current landscapes throughout the world. There are many individuals who consider climate change to be a natural and organic progression, but many studies indicate that due to excess greenhouse gas emissions, humans are accelerating global warming at an alarming rate. It’s convenient to continuously dismiss the studies and evidence that suggest climate change is real and it could have serious consequences, but when these drastic changes are taking place in our own backyard, it becomes a harsh reality. There is longstanding research, which indicates that the Colorado River has been in a drought since the early 2000’s and researchers allege that due to rising temperatures, the

The state of Michigan is a fascinating area. From its mitten-like shape, to its historical background, to the presence of the Great Lakes, Michigan has a story unlike any others. One very important part of Michigan’s story is how water has shaped the land making up the state. Seeing as the Great Lakes surround Michigan, it is obvious that the hydrologic system plays a great role in the water supply and the ecosystem of the Great Lakes. The hydrologic cycle includes evaporation, condensation, precipitation, groundwater, transpiration and runoff, all of which keep the Great Lakes functioning year after year. The University Corporation of Atmospheric Research developed an image to simply explain the hydrologic cycle as well as graphs explaining how each of the elements of the hydrologic cycle affects The Great Lakes on a monthly basis (located below).

Water is vital to the survival of man. Settlers fought over it, farmers depend on it, and communities rely on it. Fort Huachuca and Sierra Vista are no exception. Located in one of the driest states in the U.S., they rely on the San Pedro River watershed for water. Barbara Tellman and Diane Hadley’s (1999) book Crossing Boundaries, talks of travelers in the 1800s who were amazed to see cottonwood lined streams of the San Pedro after traveling for days in desert uplands (p.11). Fort Huachuca was established because of the water source at the foot of the Huachuca Mountains, needed by Captain S.M. Whiteside, his troops and their horses (Price, 2003, p31). In 1902 Congress enacted the National Reclamation Act, signed by President Theodore Roosevelt. The Act recognized the importance of water to western development. Sierra Vista continues to grow, the use of ground water increases causing the water table to drop. As the water table drops, more human, plant and animal life are affected. To understand the significance of water in the Sierra Vista/ Fort Huachuca area, it is important to know where the water comes from, why it is so important and how it can be protected. Sierra Vista’s water is not infinite. There may not be enough

As lack of water and a particularly dry climate out competes shrubs, trees, and grasslands across Colorado, erosion rates increase reducing the infiltration of moisture into the soil. Causation is believed to have come from heavy livestock grazing, fire suppression, and the introduction of exotic annual plants. Habitat problems for animals and communities that rely on ranching and hunting have been directly affected by these desertification effects. Desertification has had large ecological impacts on the state of Colorado. Vegetation and ecosystems are among the most crucially impacted by the effects of desertification. While Colorado continues its dry drought like climate, restoration of soil becomes one of the major solutions to fight off desertification. Because of the overuse of our land in past generations, we are continuing to see the harmful effects due to desertification. The overall impact on humans produced by desertification is best noticed by a diminishing food production as well as a wealth of water sources becoming dry. People in affected areas are likely to experience poor water quality, dust storms, and pollution. More importantly, as soil loses its nutrients, it no longer becomes farmable; thus, impacting local businesses, livestock, and the many people in that community. If desertification continues in Colorado, an increase of lost farmlands and livestock will pose an economic decease within agriculture markets, farmers will be forced to move to find better

Water is essential to life. It is a vital resource that makes up 70% of the earth’s surface. However, only 3% percent of the earth’s water is freshwater and two-thirds of that freshwater are frozen in glaciers and ice caps, leaving an incomparably small portion available for sustaining earth’s life forms (“How Much Water is in the Ocean?”). Rising surface temperatures, caused by greenhouse gasses that are released when burning fossil fuels, are threatening this water supply by accelerates the rate of water evaporation and limiting precipitation, which leads to droughts and water shortages. Furthermore, earth’s growing population is consuming an increasingly larger fraction of freshwater, which is causing the earth’s natural aquifers to dry up. This global water crisis is especially acute in the western United States where California is experiencing critical drought conditions that are endangering the state’s ability to sustain life. The current California water crisis will ultimately make the state uninhabitable because of several severe, long-term consequences.

The defining character of a desert is usually low levels of rainfall with under 25 cm per year. Additional to that, the relationship between rainfall and the evaporated and transpired water must be taken into consideration. “A desert is a biological community in which most of the indigenous plants and animals are adapted to chronic aridity and periodic, extreme droughts, and in which these conditions are necessary to maintain the community’s structure” (Phillips, Comus, 2000, p. 10). This means that it is the environmental and climatic conditions that have created an evolutionary pressure for the flora to develop.

HYDROLOGIC CYCLE The hydrologic cycle is a constant movement of water above, on, and below the earth's surface. It is a cycle that replenishes ground water supplies. It begins as water vaporizes into the atmosphere from vegetation, soil, lakes, rivers, snowfields and oceans-a process called evapotranspiration. As the water vapor rises it condenses to form clouds that return water to the land through precipitation: rain, snow, or hail. Precipitation falls on the earth and either percolates into the soil or flows across the ground. Usually it does both. When precipitation percolates into the soil it is called infiltration when it flows across the ground it is called surface run off. The amount of precipitation that infiltrates, versus the