Intro: Humans have been diverting water for irrigation, flood control, and a constant drinking supply for thousands of years. When populations were small, the diversions were small. Over the last 150 years human populations have grown rapidly and our technological abilities have vastly improved. These two changes, worldwide, have led to many large-scale projects that have altered the environment of sizable regions. This investigations focuses on three major water diversions: the Salton Sea, Aral Sea, and the Colorado River.
Materials: World atlas, encyclopedia, Internet access
Part 1: The Salton Sea
1. The Salton Sea is located in California. The summers are hot and dry and the winters are rainy.
2. In 1905, humans dug canals from the Colorado River to irrigate farmlands in the Imperial Valley, but huge precipitation and snow melt in the mountains flooded the Colorado River. The water rushed through the canals and filled up the Salton basin, leaving most of the town of Salton under water.
3. Water in the Salton Sea is only lost by evaporation, which leaves salt behind causing the salinity of the sea to go up causing fish to die. Also the sea’s elevation has gone up and has flooded homes and businesses.
4. The Salton Sea has provided a new ecosystem of fish and migratory birds. There has been a boom of fish making it one on the most successful fishing grounds in the world. The stability of the sea is worsening due to the high salt concentration. The salinity of the sea will keep going up until something is done.
5. The formation of the Salton Sea has provided a great fishing industry, recreational use, and bird watching. The formation has impacted the environment by bringing in many new species of birds, increasing the fish population, and has produced an increase in rainfall.
6. There have not been many huge steps taken to remediate the Salton Sea and many people say it would be very unlikely that a restoration could be done because of the massive amounts of water that would be needed to be pump out to reduce the salinity level.
7. Lake Chad is rapidly disappearing and the Salton Sea is becoming saltier. They both are in trouble and need to be resolved before further damage occurs.
Part 2: The Aral Sea
a. Kazakhstan and Uzbekistan
b. Amu Darya and Syr Darya
2. The World Bank Uzbekistan Mission.
3. In the 1960s Soviet planners built a network of irrigation canals to divert their waters into fields to water their crops.
4. The Aral Sea provided fish and water to grow crops in the Aral region.
5. The sea basin was degraded, fish were killed due to high salinity in the water, and pollution has created violent dust storms.
6. The fishing was completely destroyed, many people lost food and water, and the water was unusable making recreational use not available.
7. They are the same because their salinity levels are increasing dramatically.
8. It is mostly a dry riverbed with some water with high salinity. The dry area is very toxic and weapons are tested on it.
9. The life expectancy has dropped dramatically, infertility rose, there was an increase in birth defects, a high rate of anemia, and more cancer cases.
10. There is the possibility that if canals are dug to resupply the basin with water there may be a chance of rehabilitation.
a. In 1941, Los Angeles began to divert fresh water from the streams that flow into the lake. By the late 1980′s, the diversions provided 17 % of the city’s water supply. As a result of these diversions, the surface elevation of the lake dropped, the volume and surface area were decreased, and the salinity of the lake rose substantially.
b. They both have water that has a higher salinity than the ocean causing no