Groundwater plays a critical role in ecosystem health

Groundwater, a critical water resource around the globe, has been largely unstudied in its importance and role in sustaining ecosystems, especially in dry regions. However, a new study highlights the vital relationship between groundwater and ecosystems.

The research team used satellite imagery and groundwater monitoring data to identify thresholds of groundwater depth and seasonal change that can support sensitive ecosystems throughout California under the state’s Sustainable Groundwater Management Act framework.

The study, led by Dr. Melissa Rohde from the SUNY College of Environmental Science and Forestry (ESF), in partnership with the University of California Santa Barbara (UCSB), Cardiff University, and Desert Research Institute (DRI), was recently published in Nature Water.

Groundwater’s role in nature and ecosystems

Dr. Rohde emphasizes the importance of groundwater, stating, “A vast majority of our planet’s freshwater is groundwater, but we don’t acknowledge or manage it sustainably, resulting in serious consequences for humans and natural ecosystems.”

She continued, “Groundwater is critical for many ecosystems, but water agencies and conservationists rarely account for their water requirements. To reconcile that, our study provides a simple and practical approach to detect ecological thresholds and targets that practitioners can use to allocate and manage water resources.”

Vegetation health and groundwater depth

The study examined impacts on key plant communities using 38 years of Landsat satellite images (1985–2022) and statewide groundwater well data.

The team applied a common data transformation method in a new way to identify thresholds of vegetation greenness and groundwater depth over time, helping to inform decisions about water use and planning.

Dr. John Stella, study co-author and Vice President for Research at ESF, explained the importance of groundwater-dependent ecosystems.

“Groundwater-dependent ecosystems such as wetlands, floodplains, and riparian zones have very outsized importance on biodiversity. Upwards of 80 to 90 percent of species in a general region may be dependent on these ecosystems in some form or another,” Stella said.

“We applied a simple statistical approach to very large data sets to identify warning signs and conservation targets for a great diversity of ecosystem types,” he noted.

Drought refugia and the role of groundwater

The vast geographic scope and long timeline covered by the study allowed the team to evaluate how large-scale systems respond to major climate shocks.

These included the historical California drought from 2012–2016, and where individual groundwater-dependent ecosystems can serve as resilient drought refugia.

Co-author Dr. Christine Albano from DRI noted, “A key takeaway from this study is that we can use what we know about how deep the roots of different types of plants tend to be to approximate what groundwater levels are needed to maintain ecosystem health.”

She continued, “We found that vegetation was healthier where groundwater levels were within about 1 meter of maximum root depth, as compared to where groundwater was deeper.”

Informing water management decisions

The research team hopes that their approach and findings can help inform water management decisions in California and beyond.

“This study arms groundwater managers with an intuitive, site-specific measure that can provide a data-driven foundation to guide water allocation and ecosystem restoration efforts,” said Co-author and professor Kelly Caylor from UCSB.

“Globally, there are increasing efforts to manage groundwater resources for multiple purposes, not only to support drinking water needs or high-value agriculture,” Co-author Prof. Michael Singer from Cardiff University added.

“Our work provides a sound basis on which to develop clear guidelines for how to manage groundwater to support a wide range of needs within drainage basins in California and beyond,” he concluded.

Protecting ecosystems by preserving groundwater

This important research has provided a powerful tool for understanding and managing groundwater resources to support ecosystems.

By identifying critical thresholds and targets, this study empowers water managers to make informed decisions that balance the needs of humans and nature.

As we face the growing challenges of climate change and water scarcity, it is imperative that we act now to protect our precious groundwater resources and preserve the life they sustain.

This research serves as a call to action, urging us to recognize the vital role of groundwater in our ecosystems and to manage it wisely for the benefit of all.

The full study was published in the journal Nature Water.

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