Review of World Water Resources – Zoo House News
- March 16, 2023
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A recent review study led by the University of Texas at Austin provides an overview of the Earth’s freshwater resources and strategies for their sustainable management.
The study, published in Nature Reviews Earth & Environment, highlights the links between surface and groundwater and calls for diversified strategies for their management.
“I like to emphasize many 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 nearly 200 scientific papers to analyze the Earth’s water supply, how it is changing in different regions, and what is driving those changes. The study’s co-authors include nearly two dozen water experts from around the world.
According to research, humans primarily depend on surface water. Globally, it accounts for 75% of irrigation and 83% of municipal and industrial supplies annually. However, what we see on the surface is closely related to groundwater flow. In the United States, about 50% of annual runoff begins as groundwater. And globally, surface water that seeps into the ground accounts for about 30% of the annual groundwater supply.
Human intervention can greatly affect water exchange between surface and groundwater sources. About 85% of the groundwater pumped by humans in the US is said to be “captured” from surface water, resulting in a decrease in runoff. At the same time, irrigation from surface water can increase groundwater recharge as irrigated water seeps through the soil back to aquifers.
The study cites numerous examples of human activities affecting this flow between surface water and groundwater supplies. For example, in the early to mid-20th century, aquifers in the Columbia Plateau and Snake River Plains of the Northwest United States were replenished by surface water irrigation, while global models show that aquifer pumping limited the amount of water going into the streams , has greatly reduced by 15-21%. of global watersheds that are at risk due to reduced flows.
Despite their inherent connection, surface water and groundwater are often 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 avenues for water management through natural and engineered solutions that can help increase water supply, reduce demand, store and transport water. According to Scanlon, one of the best ways to adapt to increasing climate extremes is to store water during wet times and draw on it during droughts.
“We have droughts and floods,” she said. “We’re trying to manage those extremes, and one way we’re going to do that is by conserving water.”
Annually, the world stores about 7,000 to 8,300 cubic kilometers, or about two volumes of water, from Lake Michigan in surface reservoirs. The researchers said it was important to develop groundwater supplies as well, as they are more resilient than surface reservoirs to long-term droughts. Controlled replenishment of aquifers can help cities build their aquifers by collecting surface water and diverting it underground into aquifers. In this way, around 10,000 cubic kilometers of water are stored worldwide every year.
“This type of integrated research, connecting surface and groundwater, is exactly what’s needed to develop lasting solutions to problems like freshwater use,” said Scott Tinker, director of the Bureau of Economic Geology. “Too often, studies are conducted in isolation, and well-intentioned applications have unintended results.”
Matthew Rodell, a hydrologist at NASA Goddard Space Flight Center who was not involved in the study, said the paper provides a useful compendium of research and potential solutions for managing water supplies while maintaining water quality — a trait that’s more difficult to achieve is remote monitoring as a lot – keep an eye on.
“Water quality is one of the next targets in terms of water resource management,” he said. “I like that that was built in too.”