The availabilities and sources of our freshwater are drastically changing. Research by NASA points to major hydraulic change – wet lands getting wetter, and dry lands getting drier. This research includes a study which is the first of its kind by NASA scientists, tracking the locations of where groundwater is changing and the reasons behind it.
The Gravity Recovery and Climate Experiment (GRACE) tracked the movement of freshwater between 2002 and 2016. They used satellite precipitation data, irrigation maps and reports of human activity related to mining, agriculture and reservoir operations.
Where Do We Receive Our Freshwater Supply?
Freshwater is found in lakes, rivers, snow, groundwater, ice, and soil. It is one of the most essential resources on Earth that we use for drinking and agriculture.
During this 14-year period of the GRACE, South-western California lost four gigatons of freshwater. This is equivalent to 400,000 Olympic swimming pools. Most freshwater in California comes from rainfall and snow that collects in the Sierra Nevada snowpack. This rainwater then melts into surface waters through a series of reservoirs.
In Saudi Arabia, 6.1 gigatons of groundwater was lost between the 2002 to 2016 period. This may have been due to the growth of irrigated farmland from 1987 to present.
Conversely, the NASA team also found large trends in terrestrial freshwater storage that was not directly related to human activity in Africa’s western Zambezi basin and the Okavango Delta – a crucial water source for wildlife in Botswana. In this region, water storage increased at an average rate of 29 gigtaons per year between 2002 to 2016. This wet period came after two decades of dryness.
The Xinjiang province of north-western China, which is bordered by Kazakhstan experienced undocumented water declines throughout the first decades of this century. Specifically, they experienced a loss of 5.5 gigatons of terrestrial water storage per year, and it was not due to less rainfall.
Patterns in Groundwater Supplies:
In fact, additions to surface water occurred from climate change and glacier melting, as well as pumping groundwater out of coal mines. These additions were offset by depletions that are caused by an increase in water consumption. This is caused by irrigation and evaporation of river water from the desert floor.
Groundwater patterns are ever-changing. They are constantly subject to both environmental and human impacts. The research is significant because it illustrates some of the major aggressors in depletion and strategies that lead to increases in water production. In the end, all the research is to aid us to take better care of our water supply.