Paprika’s hydrological stations

Basin Area (km²) % glac.

Phakding 1208 28.5

Pheriche 146 38.8

Dingboche 136 37.9

Khote 148 35,3

More Paprika’s hydrology

Pangboche4000-6500m

Kharikola1600-4000m

Two smallslope basinscould bestudied in adetailedhydrologicalfield approach.

PhD project submitted for funding (feb. 2011) atUM2 CoP

Spatialized climate data sets

Available climate datasets

précipitation

Type Name Spatialresol.

Time resol.

Period Derived products Format

Precip. Aphrodite 10.3 0.25° daily 1951-2006 monthlyseasonalyearly

netcdfmatlab

Precip. CRUTS 3.0 0.5° monthly 1901-2006 seasonal, yearly netcdf

Precip. TRMM 3B42 0.25° daily 1998-2008 daily matlab

Air temp.

CRUTS 3.0 0.5° monthly 1901-2006 seasonal, yearly netcdf

Air temp.

Ncep/Ncar reanalysis17 levels

2.5° daily 1948-2009 regrided on 0.25° (*)daily, monthly, seasonal, yearly

netcdf

Air temp.

Ncep/Ncar reanalysis2m (gauss grid)

1.8° daily 1948-2009 regrided on 0.25° (*)daily, monthly, seasonal, yearly

netcdf

(*) bilinear interpolation

Comparison of seasonal (monthly) precipitation

CRU versus Aphrodite on 1952-2006 period over Koshi basin

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

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+ snowbetter agreement over a small area in the southern basin

Correlation:low correlation TRMM-Aphrodite on north-west part of the basin

Monthly precipitation correlation Aphro, TRMM

84.5 85 85.5 86 86.5 87 87.5 88 88.5

26.5

27

27.5

28

28.5

29

29.5

0.2

0.3

0.4

0.5

0.6

0.7

0.8

Monthly precipitation : mean bias Aphro-TRMM (mm)

84.5 85 85.5 86 86.5 87 87.5 88 88.5

26.5

27

27.5

28

28.5

29

29.5

-60

-40

-20

0

20

40

60

80

100

120

DHM’s hydrological balance

Awa Gaon

Mulghat Simle

Khurkot Rabuwabazar

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 km²606 : Simle 33 500 km²690 : Mulghat 5 880 km²652 : Khurkot 10 200 km²670 : Rabuwabazar 3 720 km²695 : 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

Basin Area (km²)

% glac.

Chatara 57800 2,4

Simle 33500 5,9

Awa Goan 29700 6,5

Rabuwabazar 3720 13,9

Muhlghat 5880 9,1

Khurkot 10200 8,8

Simle-AwaG 3800 0,9

The main problems :

1. For all the catchment the runoff coefficients C (annual and seasonal time steps) happen to be higher than one

0.000

0.500

1.000

1.500

2.000

2.500

600.000

1100.000

1600.000

2100.000

2600.000

1950 1960 1970 1980 1990 2000

co

eff

icie

nt d

'ec

ou

lem

en

t

Lam

e d

'eau

(m

m)

Date (année)

comparaison pluie débitBV 670 Dud Koshi

Debit annuel (mm)

pluie annuelle (mm)

coefficient d'écoulement

Exemple of the Dud Koshi catchment at the annual scale :

All catchmentsAll seasonsC >>1 in 2005

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

bv 670 Dud Koshi Hiver

0

20

40

60

80

100

120

140

160

1965 1970 1975 1980 1985 1990 1995 2000 2005

Date (année)

lam

e d

'eau

(m

m)

0.000

5.000

10.000

15.000

20.000

25.000

30.000

co

eff

icie

nt

d'e

co

ule

men

t

debit

pluie

coefficientd'ecoulement

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)

3. Inconsistency for Arun river :• Decreasing discharges at Awa Gaon and Simle• No decreasing trend observed for the precipitation

comparaison pluie débit BV 606 Arun

0.00

100.00

200.00

300.00

400.00

500.00

600.00

700.00

800.00

1986 1991 1996 2001 2006

date (année)

lam

e d'

eau

(mm

/an)

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8co

effic

ient

d'e

coul

emen

t

debit annuel

pluie annuelle

coefficientd'écoulement

comparaison pluie et débit annuel BV600.1 Plateau tibétain

0.00

100.00

200.00

300.00

400.00

500.00

600.00

700.00

1985 1990 1995 2000 2005

date (année)

lam

e d

'eau

(m

m/a

n)

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

coef

fici

ent

d'e

cou

lem

ent

debit annuel

pluie annuelle

coefficientd'écoulement

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)

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 !

Comparison of monthly temperature, discharge and precipitation (standardized values)

Show consistent pattern : maximum discharge, temperature and precipitation simultanously happen during summer (Monsoon)

Data bases

HYDRACCESS•DHM hydro & climato•EvK2 climato•Paprika hydro &climato

Contact :Pierre Chevallier

Spatial infos•Aphrodite•CRU•TRMM•NCEP•Etc.

Contacts:François DelclauxLuc Neppel

ArcGis

Projection WGS 84UTM 45N (Nepal)UTM 43N (Pakistan)

DEMSnow CoverHydrologyEtc.

Contacts:Pierre Chevallier