UCSB Professor’s research details successful groundwater management systems around the world

SANTA BARBARA COUNTY, Calif. (KEYT) – Declining groundwater supplies are an issue for communities around the globe, but a UC Santa Barbara Professor's research shows there are solutions.

Almost all of the fresh water on Earth that isn't frozen, is groundwater and more than one third of the planet's largest groundwater sources, known as groundwater basins, are dropping in level due to human consumption, making them tougher to access and even tougher to refill.

UC Santa Barbara's Dr. Scott Jasechko and his team looked into 67 cases of aquifer recovery around the world and the results of their work were recently published in Science.

"Recent work has highlighted that groundwater depletion is not an inevitability and that interventions can slow, stop, and even reverse depletion trends," shared the study. "This work profiles dozens of cases of groundwater recovery, where groundwater levels rose after a prolonged period of decline. These cases span a wide range of climate and land-use conditions and highlight how groundwater recovery can take place in both urban and rural areas and in both wet and dry climates."

The image below, courtesy of the U.S. Geological Survey, shows what makes groundwater different than surface water.

Places were groundwater is confined or bound by a confining layer of material is known as an aquifer.

The image below from the U.S. Geological Survey shows how aquifers and wells work together to bring water to the surface.

Aquifers are found around the world and preserving them is of global interest.

According to the study published this week, successful interventions for aquifers came in three categories: offsetting groundwater demands with an alternative source, policy or market changes to reduce groundwater demand, and artificial groundwater recharging.

"The cases in this review are a reminder that groundwater depletion is not inevitable," noted Dr. Jasechko. "They highlight how humans have solved this problem in different places around the globe."

The cases included almost 1,700 aquifers around the world and drilled down on where groundwater systems not only met demands, but actually replenished.

What Dr. Jasechko found is that most successful cases involved multiple forms of intervention and that most cases saw recovery within a few years if the actions taken were sufficient in scale.

"I think this emphasizes the value of multi-pronged strategies to address groundwater level declines," shared Dr. Jasechko.

Replenishing groundwater can have tangible benefits beyond protecting a crucial source of water for area populations the study found.

One notable benefit of groundwater replenishment involves slowing or even stopping land subsistence or sinking detailed Dr. Jasechko's research.

Last year, a NASA-led study used satellites to measure the vertical changes in California alongside relative sea level rise to pinpoint areas that could face the biggest impact from changing sea levels.

Existing tools for measuring sea level rise rely on tide gauge measurements which don't capture the dynamics revealed by the satellite-based research mentioned above.

The impact of a notable reliance on groundwater in California's Central Valley region is shown in the image above and has been observed from surface level measurements as well as shown in the dramatic photo below courtesy of Dr. Joseph Poland with the U.S. Geological Survey taken in Mendota, California.

While many parts of California are experiencing sharp signs of sinking, one notable example of an uplift was spotted in the Santa Barbara groundwater basin.

In fact, the Santa Barbara County Grand Jury issued a report last year about the success of the County's water management system and the City of Santa Barbara issued its decades-long draft plan about adapting local water and wastewater systems to rising sea levels.

For more information about groundwater basins in California, visit here.

Dr. Jasechko's research did note that there is a risk of overfilling aquifers that can result in compromised building stability, salinization of soils, and increased flood hazards.

Properly scaling policies and tailoring them to the region's unique hydrology is part of the process to determine just how communities can respond to local groundwater depletion.

Increasing climate variability plays a critical role in groundwater systems the research showed.

At the over 24,000-acre Jack and Laura Dangermond Preserve along the Gaviota Coast the impact of rainfall on the region's groundwater was captured over a three-year period and is shown in the graph below.

The local preserve is the largest stretch of undeveloped coastline in Southern California and the demands from people have a demonstrable impact on ground water.

The diagram below from the U.S. Geological survey shows how over pumping can cause the water table in the area to lower and can mitigate how rainfall can help naturally refill subsurface water systems.

"As the world's largest perennial and distributed freshwater resource, groundwater will play a central role in one of the most critical scientific and political challenges of this century: improving human access to fresh water for the production of food and safe drinking water while sustaining key ecosystems in a warming world," cautioned Dr. Jasechko's report published in Science. "Altogether, many cases of groundwater recovery involve coincident implementation of multiple interventions, demonstrating the merits of multi-pronged strategies to reverse groundwater declines."