Beneath Everest, the tallest water tower in the world, local communities face drinking water shortages. Scientists may have located some feasible aquifers that could provide drinking water to the communities that are increasingly falling into the grips of climate change and facing “extraordinary impacts” on their drinking water quality and availability, write a group of researchers from US and Nepali universities.
The shortage of potable drinking water is a global
crisis driven by the exponential increase in human population, heavy urban development,
and climate change. The local inhabitants who reside beneath the world’s
tallest peak, Mount Everest, a part of the Himalayas that fulfills the water
needs of more than a billion people downstream, face acute drinking water shortages.
Employing electrical resistivity tomography (ERT)
geophysical surveys, a team of researchers from the United States and Nepal sought
to identify untapped groundwater sources with potable water in the vilages of
the Khumbu region. Over a span of two years, the team conducted a total of sixteen
such surveys. Additionally, they conducted interviews with locals to gain
insights into their perceptions of water resource management and climate change,
aiming to identify conflicts related to water usage.
The geophysical surveys detected four potential
subsurface anomalies in all three villages: one in Phortse, two in Khumjung,
and one in Khunde. However, it remains to be confirmed whether the preliminary
findings coinciding with the subsurface anomalies represent real groundwater
zones with potable drinking water.
"The ERT generates images based on resistivity, the
precision of which decreases with depth," explained Ishan
Subedi, one of the authors of the paper and a graduate student from
Kathmandu University, Nepal. "Thus, objects with similar resistivity could
lead to confusion and doubt until the preliminary findings are confirmed."
Besides low abundance and dwindling availability,
scientific studies conducted in the past have confirmed the presence of fecal coliform
bacteria in surface water and spring-fed groundwater sources across the
Sagarmath National Park in Nepal, both of which fulfill the water demand of the
region. Factors contributing to the contamination of the region’s water sources
include human actions such as transportation, farming fertilizers, and human defecation,
exacerbated since the 1960s by rampant tourism, as noted by the team of
researchers led by Chasalin T. Cobb,
a graduate student at Ball State University in the United States who specializes
in hydrology.
But despite contamination, groundwater sources exhibit
a lower degree of bacterial contamination compared to surface water. Therefore, the researchers conducted geophysical explorations
of groundwater sources in three villages of Khumbu: Phortse, Khumjung, and Khunde.
Khumbu, situated in northeastern Nepal within the Everest Zone, is home to renowned
villages like Namche Bazaar, Khumjung, and Phakding.
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| Khumjung Village lies inside Sagarmatha N.P, a world heritage site. Image: Aris Gionis via Flickr |
Electrical Resistivity Tomography or ERT is a bit like
taking an X-ray of the Earth. Instead of using radiation like in an X-ray, though,
it uses electricity. Surveyors set up a bunch of electrodes on the ground’s surface
in a specific pattern. Then they send small electric current through these electrodes
into the ground. Different materials in the ground conduct electricity
differently. Some let electricity flow through easily, while others resist it.
By measuring how much electricity gets through and how fast, researchers can
figure out what’s underground. The collected data is turned into maps using special
computer software.
Through interviews with locals and key informants, Cobb
and her colleagues also revealed that the local tourism economy drives current
water management decisions and is gravely threatened by climate change.
Furthermore, locals are increasingly concerned about glacial melting, available
water quantity, and the growing and unplanned tourism economy in the face of
deteriorating water sources.
"The main challenge of conducting ERT surveys in
such remote regions is aligning the survey rods in definite patterns, which
compels researchers to use fewer rods and, consequently, achieve less accuracy
with depth," reported Subedi. "This difficulty makes identifying
deeper aquifers more challenging." Additionally, Subedi noted that the
vast glacial till obstructs clear data reading. He also mentioned that the team
is preparing for another expedition soon.
Besides direct local human impacts, long-distance pollution
transport deposits like black carbon and industrial emissions onto Himalayan glaciers,
accelerate their melting by reducing ice reflectivity. This melting alters
water availability and quality in glacier-fed rivers, affecting ecosystems and
communities.
Subedi concluded, "Some of the villages in the Khumbu
region face acute water shortages, such as Phortse, where they currently rely
on their newly built water tank as they have no other running source of
water."
The paper titled "Improving potable water access
using electrical resistivity tomography and community engagement to identify
groundwater potential zones in the village of Phortse, Sagarmatha National Park
(Khumbu), Nepal" was published in 2023 in the "THIRD INTERNATIONAL
MEETING FOR APPLIED GEOSCIENCE & ENERGY EXPANDED ABSTRACTS," published
by the Society of Exploration Geophysicists in 2023.