In other words, humans have been depleting our underground water storage to the point that in the process, we are creating unsustainability in our water use, as well as adding to climate change. With economic development and population growth, many regions of the world are seeing the demand for freshwater rapidly increase while at the same time, many of those water sources are becoming scarce.
We have already seen studies on the Indo-Gangetic Basin that accounts for a quarter of the Earth’s groundwater reserves. With 60 percent of its water contaminated and not fit to drink, the sustainability of this large terrestrial water reserve is of great concern.
And in two studies published in 2015, researchers from the University of California at Irvine, using data from the NASA Gravity Recovery and Climate Experiment (GRACE) satellites, found that one-third of the world’s 37 groundwater aquifers were in distress from over-exploitation.
In the latest study, Professor Zhenghui Xie and Dr. Yujin Zeng from CAS Institute of Atmospheric Physics incorporated a model of anthropogenic groundwater exploitation into the Community Earth System Model version 1.2 to conduct a series of simulations on a global scale.
The researchers were looking for any impacts on the ecohydrological processes and climate system caused by over-exploitation of our groundwater resources. Areas that stood out in the study were the central United States, the north China Plains and northern India and Pakistan, according to Science News Line.
“Quantifying the hydrologic and climatic responses to anthropogenic groundwater extraction not only advances our understanding on the hydrological cycle with human intervention but also benefits effective human water management for sustainable water use,” said Prof. Xie.
The study found that groundwater exploitation in some of the most vulnerable regions caused drying of the deep soil layers and increased wetting of soil near the surface. And of course, they found that heavy extraction of groundwater was causing a rapid decline in the water tables.
Keep the wetting of soil in the upper layers in mind, because this impacts cooling and increased precipitation over these areas. The study found the atmosphere also cooled where groundwater was exploited, with cooling seen over large areas in India and Pakistan and a large area in the north of China and central Russia.
Precipitation was increased in northern China because of increased evapotranspiration from groundwater irrigation. Evapotranspiration is the process by which water is transferred from the land to the atmosphere by evaporation from the soil and other surfaces and by transpiration from plants.
Decreased precipitation was seen in northern India because water vapor from the annual monsoon was weaker due to the atmospheric cooling from groundwater exploitation. “Local terrestrial water storage was shown to be unsustainable at the current high groundwater extraction rate,” according to the study.
“To address these difficulties, measures such as large-scale water diversion, improvements in irrigation efficiency, and water recycling should be implemented. Northern India may require the most urgent interventions because the monsoon circulation is weakened by groundwater use here, and both precipitation and runoff are being reduced concurrently,” according to the researchers.
This research, entitled “Hydrologic and Climatic Responses to Global Anthropogenic Groundwater Extraction” was published in Journal of Climate.
