1. Paprika’s hydrological stations

3. BasinArea (km²)% glac. Phakding 120828.5 Pheriche 14638.8 Dingboche 13637.9 Khote 14835,3

5. More Paprika’s hydrology

6. Pangboche 4000-6500m Kharikola 1600-4000m Two small slope basins could be studied in a detailed hydrological field approach. PhD project submitted for funding (feb. 2011) at UM2 CoP

7. Spatialized climate data sets

8. Available climate datasets précipitation TypeNameSpatial resol. Time resol. PeriodDerived productsFormat Precip.Aphrodite 10.30.25°daily1951-2006monthly seasonal yearly netcdf matlab Precip.CRUTS 3.00.5°monthly1901-2006seasonal, yearlynetcdf Precip.TRMM 3B420.25°daily1998-2008dailymatlab Air temp. CRUTS 3.00.5°monthly1901-2006seasonal, yearlynetcdf Air temp. Ncep/Ncar reanalysis 17 levels 2.5°daily1948-2009regrided on 0.25° (*) daily, monthly, seasonal, yearly netcdf Air temp. Ncep/Ncar reanalysis 2m (gauss grid) 1.8°daily1948-2009regrided on 0.25° (*) daily, monthly, seasonal, yearly netcdf (*) bilinear interpolation

9. Comparison of seasonal (monthly) precipitation CRU versus Aphrodite on 1952-2006 period over Koshi basin

10. Spatial comparison of monthly precipitation CRU versus Aphrodite on 1952-2006 period over Koshi basin (resol = 0.25°) monthly bias (CRU-Aphro) monthly correlation between CRU and Aphro (636 values for each cell) Bias: higher CRU values over Tibet plateau (~1000 mm/year) better agreement in the southern basin Correlation: good correlation CRU-Aphrodite on southern part of the basin

11. Spatial comparison of monthly precipitation TRMM versus Aphrodite on 2000-2007 period over Koshi basin (resol = 0.25°) monthly bias (Aphro-TRMM) monthly correlation between TRMM and Aphro (120 values for each cell) Bias: higher TRMM values over Tibet plateau and in south of Nepal (up to 350 mm/year)  probably reflect a bad aphrodite precipitation interpolation (lack of gages) over Tibet plateau higher Aphrodite values along the montains (up to 1000 mm/year)  TRMM :only rain, Aprhodite : rain+ snow better agreement over a small area in the southern basin Correlation: low correlation TRMM-Aphrodite on north-west part of the basin

12. DHM’s hydrological balance

13. Awa Gaon Mulghat Simle Khurkot Rabuwa bazar Comparison of annual/monthly discharge and precipitation - 5 sub catchments of Koshi river at Chatara (93% of Koshi catchment area at Chatara) - 600.1 : Awa Gaon 29 700 km² 606 : Simle 33 500 km² 690 : Mulghat 5 880 km² 652 : Khurkot 10 200 km² 670 : Rabuwabazar 3 720 km² 695 : Chatara 57 300 km² Aims :  Analysing the reliability of discharge measurements  Basic anlayses of the catchment hydrology Data : -Discharge : DHM data base -Precipitation : spatial mean precipitation calculated for each catchment with aphrodite data Chatara

14. BasinArea (km²) % glac. Chatara 578002,4 Simle 335005,9 Awa Goan 297006,5 Rabuwabazar 372013,9 Muhlghat 58809,1 Khurkot 102008,8 Simle-AwaG 38000,9

15. The main problems : 1. For all the catchment the runoff coefficients C (annual and seasonal time steps) happen to be higher than one Exemple of the Dud Koshi catchment at the annual scale : All catchments All seasons C >>1 in 2005

16. 2. This pattern can not be explain by snow or ice melting as it is observed in all season an mainly in Winter and October-November it does not exhibit a seasonal cycle Exemple of Dud Koshi winter (=DJF) runoff coefficient  May be it can be explain by the uncertainty of low flows measurement ? by the catchment precipitation estimations (Aphrodite)

17. 3.Inconsistency for Arun river : Decreasing discharges at Awa Gaon and Simle No decreasing trend observed for the precipitation Arun – Awa Gaon – 29700 km² Arun – Simle – 33500 km² Decreasing trend in annual discharge Break in the annual discharge time serie (near 1996-1997) No significant trend for annual precipitation (green curves)

18. 4. Inconsistency in the sub catchments contributions to the total Koshi catchment discharge We have computed the ratio Qsubcatchment/Qkoshi (annual and seasonal scale)  The sum of the 5 ratio is greater than one ! Annual contribution of the 5 subcatchments to the Koshi annual discharge (black curve)  This pattern also appears at the seasonal scale  not systematicaly the same year than for annual discharges  the years with runoff coefficient and contribution inconsistencies are not simultaneous !

19. Comparison of monthly temperature, discharge and precipitation (standardized values)  Show consistent pattern : maximum discharge, temperature and precipitation simultanously happen during summer (Monsoon)

20. Data bases

21. HYDRACCESS DHM hydro & climato EvK2 climato Paprika hydro &climato Contact : Pierre Chevallier

22. Spatial infos Aphrodite CRU TRMM NCEP Etc. Contacts: François Delclaux Luc Neppel

23. ArcGis Projection WGS 84 UTM 45N (Nepal) UTM 43N (Pakistan) DEM Snow Cover Hydrology Etc. Contacts: Pierre Chevallier