The headwater discharges of the Nepalese face of Mount Everest

Coordinator: Pierre Chevallier1
Contributors: François Delclaux1, Luc Neppel1, Jean-Philippe Chazarin1,
Frédéric Hernandez
1, Rajendra Sharma2, Elisa Vuillermoz3, Devesh Koirala4
Webmaster: Jean-François Boyer1

1 Laboratoire Hydrosciences (CNRS, IRD, Université de Montpellier), CC 57, Université de Montpellier, 163 rue Auguste Broussonnet, 34090 Montpellier, France
2 Department of Hydrology and Meteorology, Babar Mahal, Kathmandu, Nepal
3 Ev-K2-CNR Association, Via San Bernardino, 125, 24126 Bologna, Italy
4 Nepal Academy of Science and Technology, GPO Box:3323, Khumaltar, Lalitpur, Nepal



The Nepalese part of the Koshi River basin has become an important subject of studies during recent years. Several studies have been undertaken, especially in its Dudh Koshi River sub-basin, and many papers have been published in the international scientific literature (Shrestha et al. 2012; Agarwal et al. 2014; Bharati et al. 2014; Savéan et al. 2015; Nepal et al. 2014). Several reasons can be advanced for this choice:

  • Summer floods of the Koshi River at its entry in the large and densely populated Ganges River plain have been frequently catastrophic (Chakraborty et al. 2010)
  • Several glacier outburst flows in the upper valleys, especially in 1985 and 1998, have had a strong impact on local inhabitants (ICIMOD 2011)
  • The presence of five 8000-m summits (Everest, Kangchenjunga, Lhotse, Makalu and Cho-Oyu) is not only emblematic, but is also a source of mountaineering activities, with their economic fallout and their consequences on land use and the environment, including both National Parks: Sagarmatha and Makalu-Barun (Sherpa & Bajracharya 2009)
  • The potential of this basin for hydro power equipment was identified quite early (Shresta 2009)
  • Finally, the presence of the Pyramid high altitude scientific laboratory (5035m), managed since the end of the 1990s by the Italian Ev-K2-CNR Association in partnership with the Nepal Academy of Science and Technology, is an incomparable tool (Ev-K2-CNR s. d.).

Data collected

The current dataset focused on three basins, which gather all the headwater flows from the Nepalese side of Mount Everest: the Imja Khola River at Dingboche, the Khumbu Khola River at Pheriche and the Dudh Koshi River at Phakding.

The Paprika/Preshine projects have installed and now manage the Phakding, Pheriche and Dingboche hydro-stations, all averaging the recorded parameters at a 30-min time step. The hydro-stations are equipped with Campbell® or Ott® water level sensors. All the data are stored in Campbell® data loggers and are downloaded twice a year, in spring and autumn. These devices have operated with reasonably few missing data since their installation in 2010-2011 despite the severe operational conditions.

The calibration curves of the hydro-stations are established on the basis of discharge measurements using an instantaneous injection of fluorescein; the tracer in the water course is continuously detected through an automatic fluorometer (Schnegg 2002). The resulting data are processed with a homemade script using the R language. The three stations installed in rocky environments are satisfactorily stable; after 6 years of operation (2010-2015), the calibration curves were built with 47 discharge measurements in Phakding, 35 in Dingboche and 37 in Pheriche. Topographic surveys of the cross sections were made in 2011 for extrapolating the discharge values of the highest water depths.

In a first step, the discharge data collected during the Paprika project (2010-2013) are now freely available for not-commercial purpose under certain conditions (see below).

The data regarding the Preshine project period (2014-2017) will be available few months after the end of the project.

It should be noted that the Dingboche station has been heavily damaged on May 25th, 2015, caused by a flash flood and a landslide in the Nupse South Face triggered by an aftershock of the big earthquake of April 25th, 2015.

Data accuracy

Hydro meteorological field measurements are subject to a variety of errors, reducing the accuracy of the monitored time series, consequently introducing uncertainties in all of their applications. Water level uncertainties are increased by the depth/discharge calibration curve uncertainties.

The Paprika/Preshine water level data are acquired with recent automatic recording devices and stored in data loggers. As a consequence, the quality of the data is good, except when there are electronic dysfunctions, which are not negligible taking into account the very severe installation conditions. All the doubtful data were removed from the database used for this study.

Nevertheless, the discharge data for the Paprika/Preshine hydro-stations depend on the quality of the calibration curves and consequently the discharge measurements. Due to the torrential flows of the observed watercourse and the extreme conditions of the tracer measurements, it still remains a likely source of error. However, it is impossible to assess it accurately and we estimate its magnitude at less than 25%.

How to download the data?

The metadata and the pictures of the stations are available for everybody.

When logged with an id and a password, it is possible to download the discharge data series (instantaneous or at hourly, 3 hours-, 6 hours- and daily time steps) in a text file (.csv). It is also possible to display the hydrograms and zoom on it.

The id and the password are available for a single user after signing an agreement form and sending it to the data base coordinator and to the webmaster.

Download the agreement form

Sponsors and acknowledgments

The dataset was funded by the Agence Nationale de la Recherche (references ANR-09-CEP-0005-04/PAPRIKA and ANR-13-SENV-0005-03/PRESHINE), Paris, France. Part of the equipment was purchased through the "Glacioclim" Long-Term System for the Observation of the Environment, operated by the Alliance Nationale de Recherche pour l'Environnement, Paris, France.

It was locally approved by the Bilateral Technical Committee between the Ev-K2-CNR Association (Italy) and the Nepal Academy of Science and Technology (NAST) within the Ev-K2-CNR/NAST Joint Research Project.

It is supported by the Department of Hydrology and Meteorology, Kathmandu, Nepal.

The authors wish to thank the hydrologists of the Department of Hydrology and Meteorology, Nepal, most particularly Bijay Pokhrel, who initiated the Hydraccess data base, the staff of the Pyramid Laboratory in Bergamo, Kathmandu and Lobuche, the directors of the Nepalese Academy of Science and Technology and the glaciologists of the LTHE and LGGE in Grenoble, France, especially Yves Arnaud, who coordinated the Paprika project, and Patrick Wagnon, who has been based in Kathmandu at ICIMOD since 2012 and has assisted in all field visits.

In addition, they pay homage to the local observers, the local authorities, the Sagarmatha National Park and the Thamserkhu and Cho-Oyu trekking agencies with their respective staff and porters.


  • Agarwal, A., Babel, M.S. & Maskey, S., 2014. Analysis of future precipitation in the Koshi river basin, Nepal. Journal of Hydrology, 513, p.422 434.
  • Bharati, L. et al., 2014. The Projected Impact of Climate Change on Water Availability and Development in the Koshi Basin, Nepal. Mountain Research and Development, 34(2), p.118 130.
  • Chakraborty, T. et al., 2010. Kosi megafan Historical records, geomorphology and the recent avulsion of the Kosi River. Quaternary International, 227(2), p.143 160.
  • EvK2-CNR, The Pyramid. Available at: [Consulté le mars 13, 2015].
  • ICIMOD, 2011. Glacial lakes and glacial lake outburst floods in Nepal. , p.109.
  • Nepal, S. et al., 2014. Understanding the hydrological system dynamics of a glaciated alpine catchment in the Himalayan region using the J2000 hydrological model. Hydrological Processes, 28(3), p.1329 1344.
  • Savéan, M. et al., 2015. Water budget on the Dudh Koshi River (Nepal)?: Uncertainties on precipitation. Journal of Hydrology.
  • Schnegg, P.-A., 2002. An inexpensive field fluorometer for hydrogeological tracer tests with three tracers and turbidity measurements. In Groundwater and human developement. Mar del Plata, Argentina: Balkema, p. 1484 1488.
  • Sherpa, L. & Bajracharya, B., 2009. View of a High Place: Natural and Cultural Landscape of Sagarmatha National Park, Kathmandu. Available at: [Consulté le mars 13, 2015].
  • Shresta, R.S., 2009. Arun III project: Nepal's electricity crisis and its role in current load shedding and potential role 10 years hence. Hydro Nepal: Journal of Water, Energy and Environment, p.30 35.
  • Shrestha, M. et al., 2012. Modeling the Spatial Distribution of Snow Cover in the Dudhkoshi Region of the Nepal Himalayas. Journal of Hydrometeorology, 13, p.204 222.