Sherab Lhamo

A study conducted in Bhutan’s Dungju Ri and Yude Ri catchments in the Trashigang region has shed light on the perilous impact of climate change on the country’s spring water resources.

Led by Tshewang Dhendup, a lecturer at the Sherubtse College in Kanglung, the study findings were unveiled during the Bhutan Research Symposium held on September 13.

The primary objective of this research was to quantify the effects of climate change on spring flows. To achieve this, the team employed geochemical tracers to assess the contributions of various water sources, such as precipitation, snowmelt, rainwater, groundwater, and others.

The study sought to unravel the intricate mechanisms governing spring recharge processes.

Geochemical tracers played a pivotal role in uncovering essential information regarding water-rock interactions and sub-flow paths. These tracers provided critical insights into the sources, recharge mechanisms, groundwater origins, evolution, and recharge areas in Bhutan, particularly within its challenging mountainous terrain.

The study revealed a worrisome trend, emphasising the significance of groundwater in lower-elevation catchments. Groundwater availability, it was found, hinges on the presence of surface water to recharge it.

As climate change continues to diminish surface water resources, groundwater reserves are dwindling, exacerbating the crisis. Furthermore, diminishing snowfall over the years has compounded the problem, as groundwater struggles to compensate for reduced precipitation inputs, ultimately resulting in a decline in groundwater inflow into springs.

While Bhutan’s larger river basins may not currently face water shortage issues, small communities residing on mountain slopes, heavily reliant on small streams and springs, are grappling with severe water scarcity.

Springs are a lifeline, serving as the primary source of drinking water in the country, accounting for 67.6 percent of supply, followed by streams (25.7 percent), marshes (2.7 percent), ponds (2.3 percent), rivers (1.1 percent), and lakes (0.7 percent), as reported in a recent article.

The study’s key finding unveiled that approximately 69 percent of the water sources under investigation were sourced from precipitation, with spring water significantly influencing groundwater extraction practices.

These region was notably sensitive to alterations in precipitation patterns and groundwater extraction practices, aligning with previous studies that underscored the Himalayas’ heightened susceptibility to climate warming compared to lower-lying areas.

Rising air temperatures further compounded the issue, posing a risk of reduced freshwater storage in both snowpacks and glaciers.

Recent reports painted a stark picture, with 69 water sources in the country already dried up and an additional 1,856 in the process of drying up, out of a total of 7,399.

The study involved the collection of 54 water samples, encompassing main streams, tributary streams, springs, natural pond water, wetland outflow, rainwater, and soil water. Additionally, five snow samples were gathered within an elevation range spanning from 1045 meters to 3471 meters.

Springs were observed at various elevations within the study areas, either merging with streams or dissipating before reaching any streams.

Several factors were identified as contributing to the drying of water sources, including road construction, forest fires, overgrazing, land use and land cover changes, construction of transmission lines, infrastructure development, geological instability, and more.

The study underscored the pivotal role of rainwater in sustaining shallow springs and small streams primarily fed by springs during the pre-monsoon season.

Tshewang Dhendup emphasised the vulnerability of Bhutan’s water sources to shifting precipitation patterns driven by rising air temperatures in the Himalayas.

Acknowledging the challenges faced during the research, he highlighted the shortage of available experts to repair equipment malfunctions and the difficulties of balancing teaching responsibilities with research commitments.