Groundwater Depletion and Storage
Groundwater is an essential component of the country’s water supply, accounting for one out of every five gallons tapped for agriculture, energy and human consumption. According to the US Geological Survey’s first national assessment of groundwater depletion, the United States groundwater reserves dropped by nearly 264 trillion gallons between 1900 and 2008. That is enough water to fill Lake Erie twice, and researchers say that the problem is only getting worse.
Specifically, the study evaluated long-term depletion in 40 separate aquifers in the U.S., and shows that the rate of depletion from 2000 to 2008 was nearly three times greater than the average rate of depletion for the entire study period with the biggest declines occurring in the Southern Great Plains, the Mississippi Delta, and the Central Valley of California.
Leonard Konikow, a contributing hydrologist to the U.S. Geological Survey, notes that this trend in groundwater consumption is not sustainable in the long run, and can cause land to subside, cut yields from existing wells, and diminish the flow of water from springs and streams. Higher energy costs for irrigation and global sea levels are also affected.
Therefore, many states are trying hard to boost their reserves, and are looking towards innovative methods of water storage. For example, Wichita, Kansas is injecting flood waters underground, which is serving as a model for farmers in northeast Oregon who want to do the same with a small fraction of the Columbia River’s winter flows.
This underground water storage strategy has great potential because, “you don’t flood a bunch of bottomland hardwoods, or take thousands of acres of cropland out of service,” said James Dwyer, an engineer with CH2M Hill, a global engineering and construction company. In addition, water evaporation and the need to dam rivers would be reduced. In some arid areas, such as western Texas, more water is lost to evaporation than used by people.
Although underground reservoir technology is already tested and ready to go, some challenges still stand in the way. Underuse is mainly attributed to education, possibility of water contamination, and water ownership rights, but experts and supporters of the technology believe that it will become more relevant with climate change. As frequency and magnitude of extreme weather and natural disasters increases, securing clean freshwater water will be crucial.