The Colorado River
Basin Overview:
The Colorado river has its origins in the mountains of Wyoming and Colorado, the headwaters of its principal tributary, the Green, and the main Colorado river, respectively. The Green and Colorado meet in the deserts of southern Utah, before flowing into Lake Powell, the reservoir that occupies Glen Canyon, and is held back by Glen Canyon Dam. Past the dam, the river flows through Lee’s ferry before making its way into The Grand Canyon, then out of the national park and into Lake Meade, where it is used to irrigate large swaths of the desert and provide hydropower for the southwest via the Hoover Dam. On the rest of its journey to the Pacific Ocean, the great river is depleted by agricultural use, including the irrigation if the imperial valley, one of the most productive growing regions in the country. This constant exploitation of the river take its toll, however, as the river no longer reaches the Gulf of California, petering out in its significant and once vibrant delta.
River Regime Graph:
System Components:
Inputs: Snowpack in the mountains of Wyoming, Utah, and Colorado is the largest component of input for the Colorado River. Out of the mountains, the majority of area surrounding the river and its tributaries are arid with very little rainfall in most places. Generally, flows are higher in the spring and the summer, as the snow in the high country melts quickly, boosting the flow of the river. This flow is controlled by the system of dams on the river. Last year, as seen in the data above, the upper basin had the highest snowpack recorded in the last 7 years, and it was retained longer than usual, with a fairly significant increase as late as the end of May. This meant that there was more water flowing, and at a later time of the year than usual.
Outputs: The Colorado River and its tributaries provide water to nearly 40 million people from different areas, including California, Nevada, Arizona and some Native American Tribes. Water from the river is used for many purposes, such as irrigation, agriculture, hydroelectric power, supply for urban areas, and transport. Approximately 80% of the water is used for irrigation and agricultural purposes, it irrigate nearly 5.5 million acres of land. On the river, there is a total hydropower generating capacity of 4178 MW, to generate electricity for the people living in the surrounding area. Water supplied for urban areas could be used for domestic purposes, means the uses of water for household, stock, municipal, mining, industrial, and other similar purposes. The Colorado River Basin is separated into two sections, the upper and lower basin. The upper basin is mostly within Wyoming, Utah, and Colorado, and the lower basin is generally Arizona, Nevada, California, and New Mexico. Each section of the basin has the rights to 7.5 million acre ft a year, with Mexico being allotted 1.5 million acre ft per year. This allotment is provides for all consumptive uses of the river by its beneficiaries.
Flooding:
Major floods have occurred in the lower Colorado River basin in every decade since the 1840s. Since then, floods occur approximately in every 15 - 20 years. Current flooding happened in Oct 2018. Heavy December rains caused extensive flooding upstream and downstream of the Highland Lakes. $500,000 fund from Colorado water conservation to continue the floodplain map and modernization program. Colorado recently experienced one of its biggest winters. There was a large amount of snowpack, and people were afraid that when it melted, it could've increased the risk of flooding in the area.
Although rain in the arid parts of the basin is not common, when a significant precipitation event occurs it can create intense and short-lived floods. Flash floods like these can harm people and property, but they also morph the landscape. Geologic change often occurs on a massive time scale, with landscapes being altered one millions of years, but in the Colorado River Basin and the American Southwest, change can occur on the opposite side of the spectrum. When water barrels down canyon systems, it has trouble absorbing into the dry landscape, and instead of meeting resistance of vegetation or soil, it destroys everything in its path, calving off weak layers of rock and moving boulders and sediment. This can result in changes in the landforms of the area with the span of minutes. Debris also occasionally alters the path of the main river, and because the main flood cycle is so limited by the dam system, the debris from tributaries has less opportunity to be swept away by the next years rapid snowmelt. An extreme example of the impact of this type of flood is Crystal Rapid in the Grand Canyon, where a flood narrowed the river drastically, creating a new and deadly challenge for boaters from the 70's onward.
Flood prediction map:
Human Impacts:
Steamboats on the Colorado river in the
Water from the river is used for many purposes, such as irrigation, agriculture, hydroelectric power, supply for urban areas, recreational uses and transport. Agriculture uses approximately 80 percent of Colorado River water to irrigate nearly 4 million acres, providing 15 percent of America's crop output and 13 percent of our livestock production. However, agricultural activities lead to salinization. Dams constructed on the Colorado river to generate hydroelectric power. On the river, there is a total hydropower generating capacity of 4178 MW, but many of the plants are already operating below their measured capacities because of the drought. Nearly 30 percent of the energy from Hoover Dam goes to the Metropolitan Water District of Southern California, which provides drinking water to nearly 19 million people of the United States. In the past, from 1852 to 1909, steamboats were considered as the most economical way to goods between the Pacific Ocean ports and settlements and mines along the river, putting in at landings in Sonora state, Baja California Territory, California state, Arizona Territory, New Mexico Territory, and Nevada state. Steamboats were the main transportation until the advent of railroads. The Colorado river is a tourist attraction, Grand Canyon river trips typically begin at Lee's Ferry and take out at Diamond Creek or Lake Mead; they range from one to eighteen days for commercial trips and from two to twenty-five days for private trips. Hiking, backpacking, camping, skiing, mountain biking, and fishing are also among the opportunities offered by the area around the river. The reservoirs of Lake Powell and Lake Mead also offer water sports recreation.
Engineering Techniques:
Hoover Dam
Some examples of hard engineering techniques on the Colorado River are dams and aqueducts, which work to trap, and then move, the water, both generating hydropower and providing water for consumption by industry, agriculture, and municipalities. Two of the largest and best known dams in the US are on the Colorado, Glen Canyon Dam, and the Hoover Dam. Soft engineering techniques on the Colorado are difficult to find, as it has been exploited by heavy handed powers that favor big engineering projects. One example of soft engineering techniques could be the system put in place to judge snowmelt, in order to adjust reservoir levels accordingly. This system was put into place following high flows in the early 80’s. Without this low impact systems in the alpine environments where the snowpack is, there would be greater uncertainty about potentially damaging high flows downriver.
Bibliography:
Atkins, William. (n.d.). Colorado River Basin. Retrieved October 21, 2019, from http://www.waterencyclopedia.com/Ce-Cr/Colorado-River-Basin.html
Flood Mitigation. (September 10, 2019). Retrieved October 21, 2019, from http://www.ncsl.org/research/environment-and-natural-resources/flood-mitigation.aspx
Bianchi, Chris. (May 11, 2019). High snowpack could increase Colorado flood risk. Retrieved October 22, 2019, from https://www.denverpost.com/2019/05/11/high-snowpack-colorado-flood-risk/
