Yale Himalaya Initiative

environment | livelihood | culture

Prajjwal Panday on hydro-climatology of the Hindu-Kush Himalayan region

April 24, 2018

Written by: Amanda Mei

Over the past decade, Prajjwal Panday has researched the complex interactions between land, water, human, and climate systems in the Hindu-Kush Himalayas (HKH). The region, which ranges across the river basins of the Ganges, Brahmaputra, Mekong, and Yellow Rivers, pose a challenge for researchers to model effects of climate change on hydrology. On April 10, Panday gave a lecture as part of the YHI Spring 2018 Series drawing from his past and ongoing research.

The lecture entitled “Cryospheric and Hydrological Processes in the Himalayan region: An assessment of snowmelt dynamics, hydrology, and climatic hazards” represented Panday’s work as a geographer from the Earth system science perspective. Overviewing global trends such as growing precipitation extremes, Panday predicted that the wetter areas would become wetter and the drier areas drier in the HKH region. Steep gradients in mountain topography and hydrology in the Himalayan region make climate projections more difficult. But Panday noted the extreme vulnerability and the importance of research in the region surrounding Nepal and Tibet.

“Between 2003 and 2009, this region’s high mountain glacier lost about 174 gigatons of ice, which is about 9,000 sports stadiums filled with ice,” Panday said.

Panday has worked to characterize the cryosphere of the HKH region using field observations scaled up with remote sensing. Examining QuikSCAT data from NASA for the years 2000 to 2009, Panday found significant differences between the melt durations of the Eastern and Western Himalayas. Whereas melt onset is later and freeze-up earlier in the Western region, the Eastern region has a longer melt duration due to the larger contribution of monsoon rainfall. The paper was the first to map snowmelt processes in the trans-boundary Himalayas.

But Panday also spoke about the challenges and uncertainties of modeling the heterogeneous HKH region with limited field observations. In his model of the Tamor River Basin in Nepal, Panday used a Bayesian framework to constrain sensitive parameters such as glacier lapse rate and critical temperatures. While fitting available data, the model shows that 30 percent of annual runoff from glaciers in the Eastern Himalayas derives from snowmelt. In other models, Panday has observed differences between permafrost levels at high and low elevations of the Tibetan plateau.

Climatic extremes may occur more frequently in the Himalayan region in the coming decades, according to Panday. He summarized hydrological hazards such as monsoon flooding, extreme precipitation and temperatures, and glacial lake outburst floods (GLOFs). Citing a 2018 paper by Harrison et al., Panday suggested that GLOFs may have peaked in the 1930s after the Little Ice Age, although the floods still pose a significant danger to people who live within distance of 2,400 glacial lakes in the HKH region. Also mentioning hazards such as landslides and atmospheric brown clouds, Panday stressed the importance of developing food and energy security in the region that is particularly vulnerable to climate change.

Panday expressed his interest in trans-boundary water issues in the HKH region. For example, he is pursuing research on how warming temperatures associated with climate change affects surface run-off and consequently hydropower systems in Nepal. Panday sees an opportunity to learn more about human-environment interactions in the nexus between water, energy, food, and climate.

“Vulnerability of this region is a very complex picture,” Panday said. “This is a very climatological picture of natural hazards.”

Researching the linkages between climate change, anthropogenic activities, and land-water systems, Panday is an Assistant Professor of Environmental Science at Nichols College. Trained as a geographer with expertise in environmental modeling, hydro-climatology, remote sensing, and geospatial techniques, Panday is interested in the fastest changing regions of the world such as the Amazon River Basin as well as the HKH region.