There are 252 meteorological stations, out of which only 14 stations lie above 3,000 metres above sea level. Also, many of these stations do not have snow depth sensors
Nepal is rich in water resources, and the hydrologic system of Nepal is influenced or supported by mainly three systems: the monsoon in the summer, the westerly in winter, and the snow and glacier ice melt systems in the preand-post monsoon seasons.
These systems are now influenced by climate change.
Compared to a few decades ago, the dynamics of the monsoon and the snow and glacier ice melting processes have altered significantly.
These two processes are very important to the national economy. The monsoon is directly linked to the country's agricultural production as well as disasters; the better the monsoon, the better the national economy and fewer casualties due to fewer floods and landslides.
Similarly, in the low flow season, particularly during the pre-monsoon season, snow and glacier melt water serves as the primary supply of water for hydropower and other water projects.
Thus, proper monitoring of snow, glaciers and glacial lakes is essential in the higher Himalayan regions of Nepal, where several human casualties have been recorded in the past.
Based on the reports of the International Centre for Integrated Mountain Development (ICIMOD), there are 3,808 glaciers and 2,070 glacial lakes in Nepal.
Among those glaciers, only some clean glaciers are suitable for study, a few of which are currently under study.
Among Nepal's most researched glaciers are the Khumbu and Ngozumpa Glaciers in the Khumbu region, Mera Glacier in the Hinku region, Trambau Glacier in the Rolwaling Valley in Dolakha, Rikha Samba Glacier in the Hidden Valley, Mustang, Glacier AX010 in Shorong Himal (slightly west of the Khumbu region) and Yala Glacier in the Langtang Valley, Rasuwa. However, these glaciers have reduced significantly and are very small, making it not very suitable for glaciological studies at present.
Similarly, only a few glacial lakes in Nepal have been studied. The most studied glacial lakes of Nepal are Tsho Rolpa Glacial Lake - the biggest glacial lake in Nepal - in Dolakha, Imja Glacial Lake in Solukhumbu, Lower Barun Glacial Lake in Sankhuwasabha, and Thulagi Glacial Lake in Manang. Con-tinuous monitoring of these glacial lakes is still not being done.
Not only proper study of glaciers and glacial lakes is lacking in Nepal, but meteorological study of the high mountain regions is also very little. There are 252 meteorological stations (precipitation, climatology, synoptic and agro-meteor-ology stations), out of which only 14 stations lie above 3,000 metres above sea level. Also, many of these stations do not have snow depth sensors.
In such a scenario, the Himalayan Cryosphere Climate and Disaster Research Centre (HiCCDRC) is enhancing the study of the glacier and high-altitude weather stations in Nepal. The HiCCDRC at Kathmandu University (KU) has been studying the Ponkar Glacier, debris-covered glacier in Manang, since 2015 by establishing two automatic weather stations - one on the glacier and another near the glacier in Bhimthang - with temperature and rainfall sensors along the Dudhkhola sub-river basin of Marsyangdi River from Dharapani to Bhimthang Valley. Ice melt at different debris thicknesses is also studied in the glacier by installing ablation stakes.
From June 2022, the study of Gorakh Glacier be-low Himalchuli Himal in Gorkha has started by installing an automatic weather station (AWS) near the glacier with a snow depth sensor and ablation stakes on the glacier. Gorakh Glacier lies in the sub-river basin of the Budhigandaki River basin in Gorkha district. The AWS with a snow depth sensor was installed at an altitude of 3,405 metres on the left lateral moraine.
Our next plan is to install a few other weather stations and hydrological stations to estimate the temperature lapse rate and precipitation gradient in the river basin, which will be useful to run a glacio-hydrological model. Such a glacio-hydrological model will be helpful to know the impact of climate change on the river basin and will also tell us about the contributions of snowmelt, icemelt, rain and groundwater in the river water.
This study is supported by the Water Resources Research and Development Centre (WRRDC), Ministry of Energy, Water Resources and Irrigation, Government of Nepal.
Similarly, the HiCCDRC, KU is also studying two other river basins - Bheri and Marsyangdi River basins - by installing temperature and rainfall sensors at different altitudes. A temperature and rainfall sensor has been installed at Jharana Hotel, Dolpa at an altitude of 3,150 m and another at an altitude of 2,100 m at Kagini (Raju Hotel).
These two stations' data will be used to derive the temperature lapse rate and rainfall gradient, which are necessary to run a glacio-hydrological model.
Similar sensors have also been installed in the Marsyangdi River basin.
Radar Level Sensors (RLS) will also be installed soon at two sites in each river basin to measure the water level, which will be linked with the discharge of the river. This study is supported by the University Grant Commission-Nepal.
Data from stations, where a communication system for data transmission is available, will be shared with the Department of Hydrology and Meteorology (DHM), which may be useful for flood and snowfall early warning systems. These stations will also help to increase the number of stations above 3,000 metres.
Kayastha is a glaciologist, Himalayan Cryosphere at Climate and Disaster Research Centre (HiCCDRC), KU
Not only proper study of glaciers and glacial lakes is lacking in Nepal, but meteorological study of the high mountain regions is also very little.
A version of this article appears in the print on August 19, 2022 of The Himalayan Times.
