Environmental Science: How to Find Fresh Water
To effectively use freshwater resources, people must find ways to control the water flowing on the Earth’s surface or access the groundwater below. There are various ways to access the Earth’s fresh water.
Through the hydrologic cycle, water constantly moves among the oceans, the atmosphere, the Earth’s surface, and underground. Of all this water, only 3 percent is fresh water.
Most of this fresh water (about 69 percent of it) is currently stored as ice in glaciers and ice sheets; the rest is stored and flowing as lakes, ponds, and rivers (about 0.3 percent) or as groundwater beneath the Earth’s surface (about 30 percent). Less than 1 percent of the world’s fresh water is located in the atmosphere (in the form of precipitation).
To use the fresh water that flows along Earth’s surface as rivers and streams, people change where it flows, or divert it. Diversion projects are basically just manmade structures that take water from one area and bring it to areas that need it. Two of the most common diversion projects are
Aqueducts: Aqueducts are canals or pipelines that carry water from its natural source to an area that needs it. Both New York City and Los Angeles use aqueducts to divert fresh water from distant sources (the Catskill Mountains for New York and the Colorado River for Los Angeles). This type of water diversion goes all the way back to ancient Greece and the Roman Empire, though today’s versions are much more efficient.
Although diverting fresh water through aqueducts solves the problem of supplying water to large urban areas, doing so also creates problems. For one, the diverted water is no longer available in the ecosystem it originally flowed through for the organisms that depend on that water source for survival.
Using aqueducts is also likely to negatively affect people outside the urban center who depend on the natural flow of the water for their fresh water.
Dams: A dam is a structure that blocks the flow of a river, creating a large reservoir, or lake behind it where the water is stored for human use. Humans use dams for many purposes, including the production of electricity through hydropower.
But as with any manmade change to a natural system, creating dams has some negative consequences. For example, because of the way they’re constructed, dams flood large areas of land behind them, upriver, where the reservoir is located. In some instances, this flooding destroys villages and important ecosystems.
Dams also obstruct the natural flow of water and sediment downstream, and this obstruction, in turn, affects fish migration and changes the natural evolution of river habitats.