Environmental flow, hydropower project, conflict free water resources development projects, climate change effects, in Tamor River Basin, Nepal

1. Prof. Dr. Hari K. Shrestha
Nepal Engineering College
December 16, 2015
New Delhi, India
Ongoing activity of “Hydropower development in the context of climate change: Exploring
conflicts & fostering cooperation across scales & boundaries in the Eastern Himalayas”
(CoCooN-CCMCC Project)
Developing regional collaboration in river basin management in response to
climate change: Final Workshop
The impact of hydropower projects on water
availability in Tamor Basin, Koshi,
in the context of climate change

2. Tamor River Basin Location

3. Satellite image of Tamor River Basin Rivers in Tamor River Basin
Tamor River Basin: Background Info
(Pathak, 2014)

4. Location of past disaster events in the
Tamor Basin (DesInventar, 2011)
Regional Geological Map of the Tamor Basin
Tamor River Basin: Background Info
(Pathak, 2014)

5. Land use map of the Tamor Basin
Landslide hazard map of the Tamor Basin
Tamor River Basin: Background Info
(Pathak, 2014)

6. No basin specific data
Hydrological Similarity
of nearby stations

7. Trend of average annual
flow (m3/s)
Trend of peak flow (m3/s)
River flow is
decreasing
in Teesta.

8. Panday et al., 2013
Dailymeandischarge(m3/s)
Decreasing River flow at Tamor (Majhitar)
Data source: DHM
River flow is
decreasing
in Tamor.

9. Climate Change Projection of
Hewa Sub-basin, Tamor Basin,
Nepal
Data Source: DHM/ADB
Projection: Precis A1B Scenario
Type: Daily Bias Corrected
Hydrological Model: VMOD

10. 2.24
3.52
3.22
2.33
1.15
1.82
1.98
1.86 1.88
2.59
3.27 3.23
0
1
2
3
4 Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
IncreaseinaverageTemperature
0C
Month
Increase in average temperature (2050's)
Station: Melung
Projected Average Temperature
Change in Melung
Projected: 2050’s
Range: +1.15 to + 3.52 0C
Average: + 2.42 0C
Location: Melung Meteorology station
Melung
Phidim

11. 2.54
4.28
3.34
1
1.77
1.67
1.44
1.81
1.94
1.77
2.45
2.72
0
1
2
3
4
5
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
IncreaseinaverageTemperature0C
Month
Increase in average temperature (2050's)
Station: Phidim
Projected Average Temperature Change in Phidim
Projected: 2050’s, Range: +1.0 to + 4.28 0C
Average: + 2.22 0C, Location: Phidim Meteorology station

12. Changes in
Rainfall
Melung
Annual Rainfall: + 12.5 %
Monsoon rainfall: +16%
Winter: -26.6%
Phidim
Annual Rainfall: + 21 %
Monsoon rainfall: +24.6%
Winter: -26%
0
100
200
300
400
500
600
700
Rainfall,mm
Melung Rainfall , mm
0
50
100
150
200
250
300
350
400Rainfall,mm Phidim Rainfall, mm
CC
2050’s
CC
2050’s
Rainfall will reduce in dry
period and increase in wet
period. Not a good news.

13. Upper Hewa Khola
Annual average flow: + 22 %
Rainy season average flow: +33%
Winter: -5.3%
Pre-rainy season average flow: -24%
Post-rainy season average flow: +20%
Lower Hewa Khola
Annual average flow: + 34 %
Rainy season average flow: +50%
Winter: -8%
Pre-rainy season average flow: -19%
Post-rainy season average flow: +28%

14. Summary of CC modeling
• Decrease in dry season flow → water availability for HPP
and other productive uses decrease → potential source
of conflict
• Increase in wet season flow → flood, landslide, debris
flow, river bed aggradation, reservoir fill up
• Increase in temperature, number of high temperature
days will increase → decrease in production, increase in
evapotranspiration rate
• 24-hr max rainfall of 100 years return period now in 10
years
• Flow duration curve shift → Q40 value will decrease
• HFL level and scour depth will increase → need to design
structures accordingly, traditional design may not work

15. Blurred figure
Blurred data

16. Approximate HPP locations in Hewa Khola Basin, Tamor, Nepal

17. Layout of Lower Hewa HPP → More than five km of dry river stretch in the absence of e-flow

18. November 18, 2015: Hewa discharge: 4.5
m3/s, Pheme Discharge: 2.0 m3/s.
Difference between estimated/adopted
and real river flow affects water
availability for HPPs and other productive
uses of water, and can cause conflict.

19. Factors considered: monthly variations in (a) river flow, (b) e-flow,
(c) crop cycle/type, (d) population increase, (e) water supply, (f) rainfall
(g) industrial and “other” water needs, (h) return flow and (i) CC.

20. Concept too simple?
Does not consider details of each parameter?
Compromise accuracy?
Has to be, in the beginning, if it is to be
adapted/implemented by policy makers and
decision makers.

21. Activities related to linkage between
Hydropower and Water Availability
• Environmental Flows Assessment (EFA) syllabus prepared (jointly
with IWMI), approved by Pokhara University: expected to have
sustained impact as some of the graduates will eventually work in
water management sector
• EFA training conducted jointly with IWMI and participated by policy
makers and HPP designers; lower level officers convinced;
discussion with decision makers under progress
• CC modeling to estimate changes in river flows
• Water requirement estimation based on crop cycle, crop type and
other livelihood activities
• Conceptual water availability accepted by district level officers,
further works needed for implementation by DDC and MoSTE
• Primary data monitoring started, for data quality check

22. Planned Activities
• Additional hydro-meteorological data collection,
interaction with local residents on perceived CC and
impact on livelihood
• E-flows assessment seminar
• Interaction with DoED, NEA and MoSTE on adoption of
e-flows assessment method for HPPs
• Interaction with MoSTE and DDC officials on HPP water
availability assessment method
• Revise trend and CC modeling
• Finalize tool to estimate water availability for HPPs, in
each basin.

23. Regional Collaboration in response to CC
• Policy analysis related to hydropower and water
availability jointly by institutes in Nepal and India
• Biophysical issues, like e-flow, hydropower tunnel-
spring relation jointly being studied, and data shared
between Nepal and India; Pani-satsang, e-flows
training to policy makers organized jointly, CC model
outputs shared.
• Post-doc candidates having study sites in Nepal and
India.
• Hydropower proponents, HPP designers and policy
makers represented in joint discussions.
• Hoping to raise level of mutual confidence, which is the
fundamental issue in developing regional collaboration
in river basin management.

24. The activities related to the CoCooN-CCMCC Project is funded
through Netherlands Organization for Scientific Research
(NWO) by the Department of International Development
(DFID), UK.
Thank you.
For further query: email: hari@nec.edu.np