“The History of Water Supply in the Great Basin: Surviving in one of the Driest Regions of the US”

An international team including Simon Steidl from the Quaternary Research Group in the Department of Geology at the University of Innsbruck has reconstructed the evolution of groundwater in the Great Basin of the United States – one of the driest regions on Earth – up to 350,000 years in the past with unprecedented accuracy.

The findings shed new light on the effects of climate change on water supplies and provide important insights into the sustainable use of groundwater resources. The study has been published in the journal Earth and Environment Communications.

The team led by Christophe Spotl has been investigating the famous “Devils Hole” cave system in Nevada since 2010 – during the Marvelous Expeditions. Using calcite deposits in the cave, the researchers have already reconstructed the evolution of the water level in the cave up to hundreds of thousands of years ago. In the current study, this information has now been combined with a digital groundwater model of this arid region.

“Based on our extensive sampling at Devils Hole, we have a large amount of data that provides information on the evolution of the water table. By combining this with groundwater models from the USGS, we can now draw quantitative conclusions about changes in precipitation for the area.” over the past 350,000 years using accurate data from the cave,” explains geologist Simon Steidl.

In drylands such as the southwestern United States, precipitation is particularly important and groundwater data is a mirror of changes in hydroclimate. “The results could be useful in developing water management strategies and sustainable use of groundwater resources, such as how much water can be withdrawn for agricultural purposes,” Steidel says.

Dehydration increases sensitivity

The new data indicates that upwelling at Devils Hole was three to four times more sensitive to groundwater recharge during drier climates than during wetter climates in the past. “Given that drought conditions will likely increase even more in the future due to the current climate crisis, our results highlight the vulnerability of large aquifers, thus altering the most important freshwater resource in this region of the United States,” Steidel said. .

The lowest groundwater level at Devils Hole during the peak of the warm interglacial periods was not more than 1.6 meters below today’s level, which corresponds to a decrease in groundwater recharge of less than 17% compared to today’s conditions. During glacial periods, the level was at least 9.5 meters above today’s level, which means an increase in groundwater recharge of nearly 250% compared to today’s conditions.

The new information is particularly relevant for the critically endangered Devils Hole pupfish, a fish only a few centimeters in size whose sole habitat is the waters in Devils Hole. The habitat of this species is thus the smallest of all known vertebrates (about half the size of an average class). Even small changes in water availability resulting from the extraction of groundwater for irrigation or due to climate change are of paramount importance to their survival.