Josh West on water’s life-sustaining contribution in the Amazon

By now National Geographic Explorer Josh West has a strong grasp on the role of nuance when it comes to nature's processes, and consequently, when it comes to proposing solutions to environmental issues. Even the natural world’s seemingly effortless operations rest on layers of interdependent variables. The rhythm is seen in the life cycle of a single raindrop.

“Once water falls as rain onto the Earth’s surface, it begins this incredible life passing through soils, rocks, and vegetation, before returning to the atmosphere,” West says. “There is still so much to understand about that hidden life of water, especially in a place like the Amazon where it’s so vital for ecosystems, and even for the global water cycle.” 

In the densely packed Amazon rainforest, trees sustain evapotranspiration at a rate like nowhere else on Earth. Roots sip up water that is eventually expelled back into the atmosphere — billions of tonnes each day. Eventually, legions of droplets form a sort of river in the sky. The invisible but mighty current reaches a saturation point, and rain is squeezed back down to the ground. Some scurries underground for vegetation to drink again, and some runs off the clay-like, low-permeability soil quickly, becoming one with streams and rivers. 

The journey of a single raindrop in this moisture recycling factory “is a microcosm of what’s happening globally,” West says.

(See how millions of years of rainfall formed Tepuis, unique islands with flat summits, thousands of feet above South American rainforests).

For decades, West, a geologist, researcher and educator has been studying how the earth’s topography develops and sets the stage for water’s journey through soils and vegetation. In the Peruvian Amazon, where West has spent many years, the interaction between landscapes, forests and water is especially vital for maintaining the ecosystem, which is home to at least a tenth of the planet’s species.

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In collaboration with fellow Explorers Jennifer Angel-Amaya, Hinsby Cadillo-Quiroz, and students in earth science at the University of Southern California, West investigates water’s fate and consequences in the Amazon, studying its pathways from raindrop to river flow, when and how vegetation uses water along the way, and the ways that streams and rivers transport carbon and nutrients.

Natural and human-caused environmental changes can halt or rush the flow of water, redefine the path it takes, and thus, transform the map of life-sustaining nutrients it delivers.

The Amazon makes for a unique study environment. Plant roots reuptake fresh rainfall and pump it back into the atmosphere in remarkable quantities. Some science suggests this system has far-reaching, global effects on rainfall and the earth’s temperature.

“There are many different connections in the climate system,” West highlights. Using climate modeling systems, “you can take out the Amazon and see how models respond, but there are a lot of other little links that you have to consider,” he explains. “Getting the right answer depends on properly understanding the details of the water cycle today.” Nuance.

For years, the foundation of this balanced hydrological system — the Amazon floor and its canopy — has been gradually disappearing. Experts have warned the Amazon is approaching a tipping point due to the stresses of deforestation, climate change and severe droughts. However, the magnitude of individual threats, and the roles that they play in contributing to the deterioration of the Amazon, are not well known. Understanding the implications of ripping root from soil, and soil from Earth, is one area where West and his colleagues are working to fill a gap.

Nature-based solutions

Since 2022, West, Angel-Amaya (a geologist specializing in the cycle of potentially toxic metals) and Cadillo-Quiroz (a microbiologist trying to revive Amazonian soils) have worked as a team on the National Geographic and Rolex Perpetual Planet Amazon Expedition. The multi-year science and storytelling journey spans the entire Amazon River Basin, from the Andes to the Atlantic. 

For their project, the trio are exploring three sites in Peru's Madre de Dios Amazonian region to understand in detail the impact of deforestation and mining on water quality. They are using techniques never before applied to post-mining Amazonia to illuminate how the flow of water — from visible mining ponds, to hidden moisture in soils — is transformed as a result of mining, and what those changes mean for mercury pollution and greenhouse gas emissions. 

(Experience the journey of water through the Amazon's interconnected ecosystems).

Slow-absorbing soil turns to sand once it's mined. The pace of water flow, and the time the ground has to absorb the nutrients water transports, is now rushed. “In mining areas, it [water] moves many orders of magnitude faster than it does in the natural soils. If you imagine water falling on sand, it just seeps through.”

Using electrical resistivity surveys, permeametry and infilitrometry measuring tools, West and the students involved in the Expedition have been able to “peer into the otherwise hidden world of water under our feet,” West says. This part of the study is student-led.

So far, the results show how water moves through natural terra firma at a trickle. The process can, and should, take hours. Through post-mining sand, water covers the same distance in about five minutes. 

West and his colleagues think that these differences may be critical for the regrowth of vegetation and the success of reforestation efforts. Because water flows so quickly through the sand, it may not be available for plants, leaving “high and dry dead zones” across the landscape.

Even in forest regrowth areas, “The legacy of the mining activity still has its footprint on the soil a decade or more later,” West stresses. Mining craters can be seen from space, and unlike other processes that eat up forest canopy, churning up the earth cannot be easily reversed.

“If deforestation is burning a house down, mining is also digging up the foundation.” That means the same species are unlikely to sprout here again even if protected and given the chance, considering the changes in soil composition.

West and colleagues hypothesize that mining areas in Amazonia will not return to what was there before, but instead, have an uncharted future determined by their unique new landscape. Better reforestation strategies are needed with a foundation that is transforming. 

The team has begun testing an innovative, alternative approach, using nature-based solutions like planting hardy palm species that thrive in sandy, mineral-poor conditions. The hope is to encourage a wetland-type of growth that can restart biological processes, from carbon storage to soil regeneration, fertility, and microbe and nutrient retention. 

If the demonstration scale experiments, involving over 1,000 palms, prove successful, the team will significantly up their collaboration with local communities to oversee the long-term restoration of the ecosystem and facilitate the revival of forest-based life and associated functions.

To count on a future without mining is not likely, with so many livelihoods dependent upon the industry. However, greening the gold industry, as West points out, is one sustainable way forward.

At the risk of sounding controversial, West explains a walk through post-mined land is at times not the “apocalyptic hellscape” people might imagine. There are clear signs the earth is scarred, and yet, “you see jaguar footprints, you see turtles in the mining ponds and all the wildlife that are associated with the Amazon. They’re still able to live,” West cautiously describes. “This gives some hope for the future of these areas devastated by mining, but we can only help chart that future if we really understand this entirely new landscape.” 

With context, “It can feel apocalyptic, especially where active mining is ongoing” he acknowledges. There is the dichotomy of wildlife emerging at sunset to explore an aquatic system, which happens to have been ripped open. Life carries on. It’s evidence of nature’s resilience, though this shouldn’t eclipse the reality that the system is strained. “There’s a lot of potential, and there’s a lot of resilience. To me, it’s just a question like, ‘How far can we push that resilience before it breaks?’”

West has worked in the Amazon for around two decades. Through his experience, he has bore witness to the slow degradation of the landscape over the years. This compelled him to understand the underlying causes and explore potential solutions such as a novel restoration approach to rebalance this critical environment.

As a doctoral student in the early 2000s, West worked on the ways that water flowing over and through the ground sucks carbon out of the atmosphere, by reacting with rocks and by washing plant debris into rivers. These processes happen quickly in mountains, like the Andes, but more slowly in low-lying areas, like the Amazon. Studying this contrast between the Andes and the Amazon drew West to this region, where he came to appreciate the wider importance of “hidden underground water” in this natural system.

He and his colleagues continue to work on fingerprinting water that trees use in this lowland environment, and what that means for how sensitive these systems might be to climate change. In addition to the Amazon, West’s research takes him to the Himalayas, Alaska, and beyond, to work on landscapes, carbon and water.

“We have a lot to learn from catastrophic changes that transform the Earth’s surface,” West says, “whether natural catastrophes like landslides or the human-caused transformations such as accelerating permafrost thaw and mining in Amazonia.” 

(Learn about the arduous journey of reaching some of the Amazon's most pristine forests).

West was part of a team that identified and mapped nearly 60,000 landslides caused by the 2008 earthquake in Wenchuan, China. He’s traced how storms and rivers transport carbon. He’s investigated what happens when disaster strips that away.

“The world is full of many wonders, and we only have so many of those,” West marvels. To the question of what drew him to earth sciences, he elaborates on the finiteness of it all. “I think so much about the majesty of the forest. Even if we colonize Mars, there isn’t going to be an Amazon rainforest on Mars.” 

A deeper comprehension of the inner workings of these wonders is one step toward better looking after them, West continues. “We have to understand how nature works if we want to understand how to be stewards of the natural wonders that we have on our planet.” 

ABOUT THE WRITER
For the National Geographic Society: Natalie Hutchison is a Digital Content Producer for the Society. She believes authentic storytelling wields power to connect people over the shared human experience. In her free time she turns to her paintbrush to create visual snapshots she hopes will inspire hope and empathy.