ALTERATION IN SNOW MELT DRIVEN FLOW REGIME IN

CLIMATE CHANGE SCENARIO

Anita Khadka, L. P. Devkota, R. B. Kayastha Nepal Development Research Institute

Precipitation

Temperature

SCA

DDF Lapse rate Critical

Temp Runoff Coeff

Recession Coeff

RCA Time Lag

SRM Model

MODEL

Calibration & Runoff

Simulation

Runoff in Climate Change

Scenario

Temperature

Precipitation

PRECIS: ECHAM05 HadCM3

(2031-2060)

STUDY AREA

Basin Area (Km2) 5187

Area in Nepal 55%

Areal Length, km 140

Area > 5000 m 1970

SCA in Km2 692.31 (13 %)

SCA > 5000 m (%) 27.50

No. of Glacial Lakes 29

Elevation Range, m 545 – 7938

No. of Elevation Zones

11

Basin Characteristics – Sunkoshi

RESULTS

Temperature

10

15

20

25

Tem

pe

ratu

re ,

°C

Dhulikhel PanchkhalStations (trend)

ECHAM05 (°C/year)

HadCM3 (°C/year)

Panchkhal 0.047 0.042

Dhulikhel 0.047 0.043

15

17

19

21

23

25

203

0

203

1

203

2

203

3

203

4

203

5

203

6

203

7

203

8

203

9

204

0

204

1

204

2

204

3

204

4

204

5

204

6

204

7

204

8

204

9

205

0

205

1

205

2

205

3

205

4

205

5

205

6

205

7

205

8

205

9

206

0

Tem

pe

ratu

re ,

°C

Panchkhal_E Panchkhal _H Dhulikhel_H Dhulikhel_E

Historic

Projected

HYDROMETEOROLOGICAL DIAGONOSTIC

PRECIPITATION

y = 28.963x + 2761.9

y = 19.646x + 2818.8

2000

2500

3000

3500

4000

4500

20

31

20

32

20

33

20

34

20

35

20

36

20

37

20

38

20

39

20

40

20

41

20

42

20

43

20

44

20

45

20

46

20

47

20

48

20

49

20

50

20

51

20

52

20

53

20

54

20

55

20

56

20

57

20

58

20

59

20

60

Pre

cip

itat

ion

, mm

ECHAM HadCM3

Projected

y = 23.456x + 2511.2

0

500

1000

1500

2000

2500

3000

3500

4000

4500

Pre

cip

itat

ion

, mm

Historic

Discharge

y = -2.5113x + 274.35

0

50

100

150

200

250

300

350

Dis

char

ge, m

3/s

0

10

20

30

40

50

60

70

800

200

400

600

800

1000

1200

20

00

20

00

20

01

20

01

20

01

20

02

20

02

20

03

20

03

20

03

20

04

20

04

20

05

20

05

20

06

20

06

20

06

20

07

20

07

20

08

20

08

20

08

Pre

cip

itat

ion

, mm

Dis

char

ge, m

3/s

Average ppt Mesured Computed

0

500

1000

1500

2000

2500

2000 2001 2002 2003 2004 2005 2006 2007 2008

Dis

char

ge,m

3/s

Measured

Computed

SIMULATION RESULTS Calibration Year: 2001 NSE: 0.88 Dv: 7.32

On average NSE: 0.81 Dv: 4.74

SNOW MELT RESULTS

0

100

200

300

400

500

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

ECHAM HadCM3

00-08 41-50 51-60 31-40

Season % contribution Average 6.41 Winter 21.17

Pre-monsoon 14.87 Monsoon 4.28

Post-monsoon 19.53

ECHAM05 HadCM3 10.09 9.14

29.07 20.95

18.91 18.27

6.85 6.39

20.52 19.59

Baseline 2030-2060 (av)

RUNOFF

y = 1.4974x + 161.39

y = 1.3246x + 163.51 100

130

160

190

220

250

20

31

20

32

20

33

20

34

20

35

20

36

20

37

20

38

20

39

20

40

20

41

20

42

20

43

20

44

20

45

20

46

20

47

20

48

20

49

20

50

20

51

20

52

20

53

20

54

20

55

20

56

20

57

20

58

20

59

20

60

Flo

w in

m3

/s

ECHAM HadCM3

Season 2031-2040 2041-2050 2051-2060

ECHAM HadCM3 ECHAM HadCM3 ECHAM HadCM3

Average -9.83 -10.25 1.38 2.44 7.33 5.49

Winter -0.92 -3.10 3.56 10.40 5.41 8.10

Pre-monsoon 2.85 -4.75 19.41 5.60 34.18 8.85

Monsoon -12.99 -12.04 -0.78 -4.41 4.54 3.18

Post-monsoon -1.78 -6.21 4.27 42.06 12.50 17.58

PERCENTAGE CHANGE IN FLOW

RUNOFF RESPONSE– PROJECTED PERIOD

0

100

200

300

400

500

600

700

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Dis

char

ge, m

3/s

00-08

31-40

41-50

51-60

0

100

200

300

400

500

600

700

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Dis

char

ge, m

3/s

00-0831-4041-5051-60

Had

CM

3

ECH

AM

05

RUNOFF RESPONSE– PROJECTED PERIOD

Decade ECHAM05 HadCM3

Qmax N Qmax N

2031-2060 2384.53 41 2171.76 31

2031-2040 2000.17 11 1759.63 7

2041-2050 2384.53 17 1736.07 9

2051-2060 2023.42 13 2171.76 15

0

500

1000

1500

2000

2500

3000

2031 2033 2035 2037 2039 2041 2043 2045 2047 2049 2051 2053 2055 2057 2059

Dis

chag

e, m

3/s

ECHAMHadCM3Peak Q

FREQUENCY & MAGNITUDE OF PEAK FLOWS Qmax in baseline = 1195.8m3/s

CONCLUSION

The daily discharge is efficiently simulated by SRM model in Sunkoshi basin

Gradual increase in snow melt contribution follows the pattern of increasing temperature.

Changes in precipitation is correlated to variation in runoff (also peaks) generated in the basin.