Water in the rocky layer cake beneath us

Konza Prairie Biological Station

Featured Image: Konza Prairie near Manhattan, Kansas, USA. Credit: David Litwin.

Paper: Toward a new conceptual model for groundwater flow in merokarst systems: Insights from multiple geophysical approaches.

Authors: Sullivan, P. L., Zhang, C., Behm, M., Zhang, F., & Macpherson, G. L.

The dissolution of limestone by atmospheric water forms a set of recognizable features collectively known as karst: enormous caves with stalactites and stalagmites, sinkholes, chasms, and narrow, towering  columns of rock. The hydrology of karst landscapes is often incredibly complex, as water can flow rapidly through dissolution-formed conduits below ground, and topography offers fewer clues to groundwater flow than in most other landscapes. While dramatic karstic landscapes have received a lot of scientific attention, even smaller limestone units can host karst features that affect hydrology.

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The Fate of Aquifers, and What Controls It

Paper: Divergent effects of climate change on future groundwater availability in key mid-latitude aquifers

Authors: Wen-Ying Wu, Min-Hui Lo, Yoshihide Wada, James S. Famiglietti, John T. Reager, Pat J.-F. Yeh, Agnès Ducharne, and Zong-Liang Yang

The ground I’m standing on feels solid, but it’s really full of porous rocks. The holes in these rocks are all different sizes, and water can flow through and between those with larger holes. Together, bodies of rocks that are saturated with water form aquifers. As groundwater supplies more than a third of the water humans use, groundwater and the aquifers that contain it are vital. They are especially vital in mid-latitude arid and semi-arid regions without enough surface water. In their recent research, Wen-Ying Wu and their collaborators studied the future of aquifers in such regions and what factors control it.

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Looking below ground for secrets to drought resilience

Santa Ynez Mountains

Featured image: Oak savanna near the Santa Ynez mountains in California. Clyde Frogg, public domain.

Paper: Low Subsurface Water Storage Capacity Relative to Annual Rainfall Decouples Mediterranean Plant Productivity and Water Use From Rainfall Variability

Authors: Hahm, W. J., Dralle, D. N., Rempe, D. M., Bryk, A. B., Thompson, S. E., Dawson, T. E., & Dietrich, W. E.

Between 2011 and 2016, a severe drought killed over 100 million trees in California. However, not all places responded to this drought in the same way. In some locations, trees and other plants seemed hardly affected, while in other places mortality was widespread. What caused this difference? In a 2019 study, Hahm and colleagues explored the role that water storage in ecosystems has on their resilience to drought. With extreme droughts becoming more common due to climate change, understanding why certain areas are more vulnerable is important for making predictions and improving forest management.

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Do Microbes Release Fluorine from Rocks?

Image of soil microcosm

Featured Image used with permission of photographer (Cassi Wattenburger)

Paper: Indigenous microbes induced fluoride release from aquifer sediments

Authors: Xubo Gao, Wenting Luo, Xuesong Luo, Chengcheng Li, Xin Zhang, Yanxin Wang

My science textbook taught me that fluorine (F) was really important for dental health, and I’ve since learned that both excessive and insufficient amounts of fluoride in groundwater can cause health issues. While the chemistry behind the release of fluoride ions from rocks or sediments into groundwater is well understood, the microbiology of this process is not. Specifically, scientists have been wondering whether microbes could speed up the release of F from sediments into groundwater. 

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The Extraction of Hidden Waters: 11th century Persian scientist laid the foundations for hydrology and water engineering

Qanat: Aerial View

Featured Image: Areal view of the vertical shafts of a qanat in Jupar, Iran. S.H. Rashedi / CC BY-ND via UNESCO.

Paper: The millennium-old hydrogeology textbook The Extraction of Hidden Waters by the Persian mathematician and engineer Abubakr Mohammad Karaji (953 CE–1029 CE)

Authors: Ataie-Ashtiani, B., & Simmons, C. T.

Reliable sources of water are essential for every civilization. However, the Western science of hydrology is relatively young. It started perhaps at the turn of the 19th century when John Dalton completed the first water balance for England and Wales by estimating the amount of water that fell as precipitation and left as evaporation and flow from rivers to oceans. Since ancient times, civilizations have built water infrastructure like aqueducts and wells, and writings by Aristotle and Plato suggest that the ancient Greeks had a basic understanding of the water cycle. Though in many respects, the study of hydrology in Europe and the Mediterranean stagnated between the time of these early philosophers and the 19th century.

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Thickets and patches: woody plants are changing water availability in dry landscapes

Featured Image: Sparse woody plant encroachment, known as xerification, occurs here in the Chihuahuan Desert north of Coyame, in Chihuahua, Mexico. Source: Ricraider / CC BY-SA via Wikimedia Commons.

Paper: Woody Plant Encroachment has a Larger Impact than Climate Change on Dryland Water Budgets

Authors: A.P. Schreiner-McGraw, E.R. Vivoni, H. Ajami, O.E. Sala, H.L. Throop, and D.P.C. Peters

Almost half of the land on Earth is arid, with little precipitation. Arid lands are home to roughly 20% of the world’s human population, and to much of the world’s livestock as well. Arid lands are changing rapidly, both with respect to land cover and water availability. While the effects of climate change on arid places have attracted a lot of attention, the encroachment of woody plants into grasslands is also rapidly transforming arid landscapes. New research shows that the effects of woody plant encroachment are even more important than climate change for the water budget of arid ecosystems.

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