Altering the Environment Answers

The Aswan Dam’s benefits include flood control, dependable water storage, expanded irrigation, hydroelectric power, and improved navigation. Its costs include the displacement of Nubian people, loss of fertile silt downstream, increased soil salinity and waterlogging, ecological damage, and reduced fish populations.

Three technologies are irrigation canals, which carry Nile water to farmland; devices such as shadufs and water wheels, which lift water to fields; and boats, which allow transportation and trade along the river. These technologies helped people farm, obtain water, and connect communities.

Technologies such as chinampas allowed the Aztecs to create fertile artificial farming plots in the shallow lake. Aqueducts and canals brought water to homes and fields, while dams and drainage systems helped control flooding. In modern times, pumps and wells provide additional water, and tunnels and drainage channels remove wastewater and storm water. These technologies helped Mexico City grow, but groundwater pumping has also caused the land to sink and contributed to water shortages.

Two important technologies are desalination plants, which remove salt from seawater to produce freshwater, and air-conditioning systems, which cool indoor spaces and make Dubai’s hot climate more livable.

The technologies used in Dubai have significant environmental costs. Desalination requires large amounts of energy and releases concentrated salt brine that can harm marine ecosystems. Air conditioning consumes substantial electricity and increases greenhouse-gas emissions. Watering landscaping and maintaining artificial green spaces uses scarce freshwater, while large construction projects can destroy or disturb coastal habitats.

Responses may vary but should include some or all of the following information: Humans face two major environmental challenges in Dubai. The first is the lack of freshwater resources. The second is the warm and dry climate, which exacerbates pressure on scarce freshwater resources. Rapid population growth due to the discovery of petroleum in the 1960s has dramatically increased the demand for freshwater. Two technologies have helped humans survive in Dubai despite these significant environmental challenges. The invention of climate control technologies like evaporative cooling and air conditioning have allowed humans to survive in a climate with an average daily temperature of 90 degrees. The technology of desalination, which transforms saltwater into freshwater resources through the process of reverse osmosis (the heating and filtering of saltwater), has provided Dubai with 90 percent of its freshwater needs.

Responses may vary but should include some or all of the following information: The construction of the Aswan Dam in Egypt has provided many benefits, but they have come with a cost. Benefits include the creation of Lake Nasser, one of the world’s largest artificial lakes; the production of hydroelectricity to supply 15 percent or more of Egyptian energy needs; and the elimination of unpredictable seasonal flooding. Costs associated with the dam include the displacement of thousands of Nile Valley residents in Egypt and Sudan; the reduction of fertile soil deposits, which has changed native plant species and required the use of more artificial fertilizers in agricultural production; and the billion-dollar price tag of the dam’s construction.