Review of world water resources

Date:
March 15, 2023
Source:
University of Texas at Austin
Summary:
A recent review study provides an overview of the planet's
freshwater supplies and strategies for sustainably managing them.


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FULL STORY ==========================================================================
A recent review study led by The University of Texas at Austin provides
an overview of the planet's freshwater supplies and strategies for
sustainably managing them.


========================================================================== Published in Nature ReviewsEarth & Environment, the study highlights the connections between surface and groundwater and calls for diversified strategies for managing them both.

"I like to emphasize a lot of solutions and how they can be optimized,"
said lead author Bridget Scanlon, a senior research scientist at the
UT Bureau of Economic Geology, a research unit of the Jackson School
of Geosciences.

The study draws on data from satellites, climate models, monitoring
networks and almost 200 scientific papers to analyze the Earth's water
supply, how it's changing in different regions and what's driving these changes. The study's co- authors include almost two dozen water experts
from around the world.

According to the research, humans primarily rely on surface
water. Globally, it accounts for 75% of irrigation and 83% of municipal
and industrial supply annually. However, what we see at the surface is
tightly connected to groundwater flow. In the United States, about 50%
of annual streamflow starts as groundwater. And globally, surface water
that seeps into the ground accounts for about 30% of annual groundwater supplies.

Human intervention can strongly influence the exchange in water between
surface and groundwater sources. About 85% of groundwater pumped by
humans in the U.S.

is considered "captured"from surface water, which leads to declines in streamflow. At the same time, irrigation sourced from surface water can increase groundwater recharge as irrigated water seeps through the ground
back to aquifers.

The study cites numerous examples of human activity affecting this flux
between surface water and groundwater supplies. For example, surface
water irrigation recharged aquifers in the early to mid-1900s in the Northwestern U.S.' Columbia Plateau and Snake River Plain, while global
models show that groundwater pumping has greatly reduced the volume of
water going to streams, with 15-21% of global watersheds at risk because
of the reduced flows.

Despite their inherent connection, surface water and groundwater are
frequently regulated and managed as separate resources. According to
the researchers, future water resilience depends on recognizing that
surface water and groundwater behave as a single resource -- and acting
on that knowledge.

The study describes different ways for managing water through both natural
and engineered solutions that can help increase water supplies, reduce
demand, store water and transport it. According to Scanlon, one of the
best ways to adapt to increasing climate extremes is storing water during
wet times and drawing on it in times of drought.

"We have droughts and we have floods," she said. "We are trying to
manage those extremes and a way to do that is to store water." Annually,
the world stores about 7,000-8,300 cubic kilometers, or about two Lake Michigan's worth of water, in surface reservoirs. The researchers
said it was important to continue developing groundwater supplies,
too, because they are more resilient than surface reservoirs during
long-term droughts. Managed aquifer recharge can help cities build up
their groundwater supplies by collecting surface water and diverting it underground into aquifers. Globally, about 10,000 cubic kilometers of
water is stored this way each year.

"This type of integrated research, linking surface and groundwater,
is exactly what is needed to develop lasting solutions to issues such
as fresh water use," said Scott Tinker, the director of the Bureau
of Economic Geology. "Too often studies are done in isolation, and well-intended applications have unintended outcomes." Matthew Rodell,
a hydrologist at NASA Goddard Space Flight Center who was not involved
in the study, said that the paper offers a useful compendium of research results and potential solutions for managing water supplies while also
keeping water quality -- a characteristic that's more difficult to
monitor remotely than quantity -- in mind.

"Water quality is one of the next targets in terms of being able to manage water resources," he said. "I like that this was incorporated as well."
* RELATED_TOPICS
o Earth_&_Climate
# Water # Drought_Research # Environmental_Issues #
Recycling_and_Waste
o Science_&_Society
# Resource_Shortage # Environmental_Policies #
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========================================================================== Story Source: Materials provided by University_of_Texas_at_Austin. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Bridget R. Scanlon, Sarah Fakhreddine, Ashraf Rateb, Inge de
Graaf, Jay
Famiglietti, Tom Gleeson, R. Quentin Grafton, Esteban Jobbagy, Seifu
Kebede, Seshagiri Rao Kolusu, Leonard F. Konikow, Di Long, Mesfin
Mekonnen, Hannes Mueller Schmied, Abhijit Mukherjee, Alan MacDonald,
Robert C. Reedy, Mohammad Shamsudduha, Craig T. Simmons, Alex Sun,
Richard G. Taylor, Karen G. Villholth, Charles J. Vo"ro"smarty,
Chunmiao Zheng. Global water resources and the role of groundwater
in a resilient water future. Nature Reviews Earth & Environment,
2023; 4 (2): 87 DOI: 10.1038/s43017-022-00378-6 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2023/03/230315143846.htm

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