Paprika - Preshine hydrology data sets in the Everest Region (Nepal). 2010-18Authors: Chevallier P., Delclaux F., Wagnon P., Neppel L., Arnaud Y., Esteves, M., Koirala D., Lejeune, Y., Hernandez F., Muller R., Chazarin J-P., Boyer J-F, Sacareau I. DOI : 10.23708/000521 |
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Weather stations: Pyramid (PYR), Pheriche (PHE), Pangboche (PAN), Phakding (PHA), Kharikhola (KHA), Mera School (MER), Namdroling Monastery (MNA), Balukop (BAL), Paramdingma (PAR), Pangom Monastery (TCM) |
PresentationThe 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:
Data collectedThe data set focused on five basins. Four of them gather the headwater flows from the Nepalese side of Mount Everest: the Imja Khola River at Dingboche, the Khumbu Khola River at Pheriche, the Touche Khola at Pangboche and the Dudh Koshi River at Phakding. The fifth one is located in a middle mountain environment on an affluent of the Dudh Koshi River downstream from Phakding: the Karikhola River. The Paprika(2010-2013) and the Preshine (2014-2018) projects have installed and managed the 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 Dingboche station was destroyed in May 2015 by a replica of the Gorkha earthquake (25th April 2015) and not reinstalled for stability reasons. 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), except for Tauche Khola, which is calibrated using kitchen salt. The resulting data are processed with a homemade script using the R language. Topographic surveys of the cross sections in Phakding, Dingboche and Pheriche were made in 2011 for extrapolating the discharge values of the highest water depths. The discharge data collected during the Paprika and Preshine projects (2010-2017) are freely available for not-commercial purpose under certain conditions (see below) with hourly and daily time steps. In addition temperature and precipitation data acquired by the projects are available at eight weather stations (Phakding, Pangboche, Kharikhola , Mera School, Namdroling Monastery, Paramdingma, Pangom Monastery and Balukop) at hourly and daily time steps. The stations were equipped with Campbell® sensors in Phakding and Hobo® sensors in the others places. Because the Hobo® sensors do not work satisfactorily, they have been replaced with Tinytag sensors in May 2016. Nevertheless other meteorological stations are existing in this area managed by the Ev-K2 / CNR Italian association and by the Department of Hydrology and Meteorology, Government of Nepal. Additional high altitude data are available through the French Observation National Service (SNO) Glacioclim*, especially precipitations in Pheriche and Pyramid, which are equiped with Geonors® sensors, actually considered as the most reliable for measuring combined snow and rain precipitations. Nevertheless other meteorological stations are existing in this area managed by the Ev-K2 / CNR Italian association and by the Department of Hydrology and Meteorology, Government of Nepal. * site in French: https://glacioclim.osug.fr/spip.php?article75 Data accuracyHydrometeorological 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%. Regarding the weather stations, the temperature is given with a good accuracy (+/- 0.1 °C). However, due to several factors (type of device, wind, location, etc.) the uncertainty on the precipitation is higher. In Pheriche and Pyramid it is globally (rain and snow) assessed as +/- 15%. In Phakding and Pangboche, the uncertainty is +/- 10% for the rainfall and the measured value is considered unreliable for the snowfall, which can be important during the winter months in Pangboche while it is negligible in Phakding. 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 (at hourly 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. How to quote the dataset?Chevallier, Pierre, François Delclaux, Patrick Wagnon, Luc Neppel, Yves Arnaud, Michel Esteves, Devesh Koirala, Yves Lejeune, Frédéric Hernandez, Rémi Muller, Jean-Philippe Chazarin, Jean-François Boyer, Isabelle Sacareau. 2017. Paprika - Preshine hydrology data sets in the Everest Region (Nepal). 2010-18. Data base. 2017. https://doi.org/10.23708/000521. Sponsors and acknowledgmentsThe 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. References
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