Designing Climate Resilient Hydropower Sector: The Case of Nepal - UNESCO
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Climate-Resilient Water Management Approaches: Adaptation in an Age of
Uncertainty
A webinar series from UNESCO, AGWA, & ICIWaRM
Webinar 5 | Climate Risk Assessment on Hydropower
Designing Climate Resilient Hydropower Sector:
The Case of Nepal
Divas B. Basnyat and Dibesh Shrestha
Nepal Development Research Institute (NDRI)
Kathmandu, Nepal
Wednesday, 10 March 2021
08:45-10:15 UTC / 14:30-16:00 Kathmandu
1
Outline
• Hydropower in Nepal
• Climate and hydrological regime
• Rationale
• Methodology
• Key messages
• Vulnerability Assessment
• Adaptation pathways
• Barriers and Entry points
Divas B. Basnyat and Dibesh Shrestha, 10 Mar 2021 2
Hydropower in Nepal
Divas B. Basnyat and Dibesh Shrestha, 10 Mar 2021
3
Hydrology:
Hydrological/Climate Regime Snow / Glacier Melt
contribution -Rainfall-runoff
78°E to Discharge( %) -Glacier melt
-Snow melt
-Baseflow
Indian Summer
Monsoon (80%
rain in JJAS) H. Biemans et al. (2019)
• Catchment response – glacier (>~5,000m) and
snow-fed (>~3,000m), rain-fed
• Geo-hazards– Landslides, Landslide Dam Outburst
Floods, GLOFs, Flash Floods and Riverine Floods,
Debris Flows
4
Divas B. Basnyat and Dibesh Shrestha, 10 Mar 2021
Rationale
Climate Risk Assessment Approach Top-down Approach Bottom-up Approach
• GCM-based Top-Down or A priori scenario
definition Future Climate
• Bottom-up Approach or Ex post scenario Climate Risks
definition
Challenges
Climate System
• Highly variable topography and climate of Driven Driven
Nepalese Catchments
• Future changes are highly uncertain
• Current actions for future risks
What is needed is a Robustness-based
approach emphasizing preparedness for a Impact Vulnerability
range of possible futures. Assessment Assessment
5
Divas B. Basnyat and Dibesh Shrestha, 10 Mar 2021
Types of Uncertainty
• Climate change uncertainty
• Most models project increased monsoon
Climate Projections : 2040-2059
precipitation, but no agreement on winter
precipitation
• Wide variations on level of warming
(temperature)- glacier/snow melt,
evapotranspiration
• Precipitation extremes projected to increase
– sedimentation, floods, landslides
• Elevation dependent warming
• Other uncertainties
• Regulatory and policy- tariff, national
market, cross-border trading, power mix
RX1day
(including variable renewables- solar, wind)
• Project variables - Cost and time overrun,
discount rates
6
Divas B. Basnyat and Dibesh Shrestha, 10 Mar 2021
Methodology
• Step 1- Vulnerability
Assessment using the
bottom-up Climate Risk
Assessment (CRA)
approach;
• Step 2- Identification of
Adaptation Options using the
Adaptation Pathways
approach;
• Step 3- Understand and
address mainstreaming of
adaptation in the hydro-power
sector through Institutional
Analysis and identification of
entry points and barriers.
NDRI, PAC & GCAP, 2016 7
Divas B. Basnyat and Dibesh Shrestha, 10 Mar 2021
Stakeholder-defined Performance Indicators
Stakeholders Key Performance Indicator (KPI)
Government Policy Power System Reliability and Quality, Marginal
Maker, Regulator Cost, Dam Safety, Design Standards, Social and
Environment Impacts Resilience
Financial Project Economics (Cost and Benefit Stream),
Institutions/ Lending Social/Envi Impacts, Dam Safety in terms of:
Agencies
Project developer Project economics (NPV, FIRR), Adaptation Cost,
(private and public) Seasonal Energy Generation and Reliability (firm, • Safety
secondary)
Project Designer, Design Flood, Geo-hazards, GLOF, Sediment, • Water/Energy
Hydrologists, Water Availability (Hydrology) Security
Engineers
Communities, Dam Safety, Flood and Geo-hazard Risks, Flow
• Economics
Environmental Variations, Environmental Flows
Stakeholders
8
Divas B. Basnyat and Dibesh Shrestha, 10 Mar 2021
Stress Test – Case Study 200
Base +1 C°
Catchment Response +2 C° +3 C° U/S
– Hydrological Model 150
+4 C° +5 C°
Climate Input
Yield(mm)
100
50
0
1 2 3 4 5 6 7 8 9 10 11 12
Sediment Concentration
50,000
45,000
Concentration (ppm)
40,000
Hydropower Model 35,000
30,000
25,000
1000 20,000
%
15,000
IRR 750 10,000
Energy (GWhr)
5,000
500 -
Feb-11 Apr-11 Jun-11 Jul-11 Sep-11 Nov-11 Dec-11
250
0
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Divas B. Basnyat and Dibesh Shrestha, 10 Mar 2021
Economic Model 9
Current climate and hydrological variability is a major challenge
for Nepal’s hydro- sector
However, there is large variation in this variability
• Higher variability in smaller catchments, higher in rainfed than in snow-fed catchments
• Run-of-river (ROR) projects more affected by variability than storage projects
• Sediment load generally high, particularly on some catchments
ROR Projects
50
Storage Projects
Energy (GWhr)
30
Storage > 50 % of Monsoon
High – snow fed
Runoff Storage = 8 % of Monsoon Runoff 10
1000 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec -20% P, +3 T Extreme Case
300
750
200 30
Energy (GWhr)
Energy (GWhr)
500
Energy (GWhr)
100
250 20 Rain-fed
0 0
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 10
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
10
Divas B. Basnyat and Dibesh Shrestha, 10 Mar 2021The greatest impact of climate change is from increased climate
induced hazards, rather than from changes in water availability
• Financial performance (IRR) of hydro projects designed under current
tariff and PPA rates are within performance threshold for projected
change
• Increased climate induced hazards – sediment, extreme floods, GLOFs,
LDOFs- more important risk and will be exacerbated by climate change
8000
Discharge (m3/sec)
6000
GLOF Risk 4000
2000
0
0 10 20 30 40 50 60 70 80 90 100
Distance (km)
Tsho Rolpa Thulagi Lake
Imja Tsho Upper Marsyangdi A
Dudh Koshi Storage Tamakoshi III / II
8000
Discharge (m3/sec)
6000
4000
2000
0
0 2 4 6 8
Travel Time (hrs)
Tsho Rolpa Thulagi Lake
Imja Tsho Upper Marsyangdi A 11
Divas B. Basnyat and Dibesh Shrestha, 10 Mar 2021The impact of climate change on hydropower sector is
additional to other factors
In the short-term, current and new plants affected by:
• Current variability, climate- induced geo-hazards, and
• Uncertainty on institutional and regulatory issues related Base IRR 12%
to tariffs and pricing, export opportunities, construction
costs (and risks of delays and over runs) and project CC IRR 11.2%
financing
Adapt in design IRR 10.9%
For future plants (after 2030), the impacts of climate change
could be much more significant,
• However, design of these plants need not be finalized Learn, Act later IRR 11.4%
now: there is opportunity to learn more about emerging
trends and changes, and adjust these investments
• This requires preparation and action today, e.g. on
hydro-met data and monitoring
12
Divas B. Basnyat and Dibesh Shrestha, 10 Mar 2021Current power system suffers from inefficient power mix –
resulting in high economic costs Run of River Projects
• Projects designed under current regime (pricing,
market and regulatory policy) may not perform as
designed with future changes (uncertainty)
• Current power mix - 10% Storage and 80% RoR;
Future – approx. equal capacity (47% each) with
energy mix at 72% for ROR and 18-22% for
storage
100% Storage Projects
Capacity Mix, %
80%
60%
40%
System Expansion 20%
Plan 0%
2045
2021
2023
2025
2027
2029
2031
2033
2035
2037
2039
2041
2043
2047
2049
Base Case ROR Baae Case Storage
CC Case ROR CC Case Storage 13Adaptation Pathways
Iterative climate risk management Low or no-regret options
1. Addressing existing climate Options that bring immediate economic
variability i.e. current adaptation benefits, and build future resilience to
What action to take now?
Current plants gap future changes
2. Considering future climate change Options that allow reductions in future
in immediate decisions with long risks, e.g. risk screening, low cost over-
life-times design, flexible design, provide greater
robustness
Planned plants
3. Planning for future climate Iterative plans for future major changes
challenges, with uncertainty and an Monitoring programs and iterative
iterative (learning) in mind portfolios to address future risks
Learning over time
14
Future risks Divas B. Basnyat and Dibesh Shrestha, 10 Mar 2021Institutional Context, Barriers and Entry Points
• Stakeholder roles and responsibilities, exposure to CC risks,
mechanism to implement adaptation, and their influence
• Barriers: investment, institutions, policy (PPAs, regulations)
• Mainstream adaptation into the institutional and policy/sector
landscape e.g. policy intervention addressing vulnerabilities
to the specific context, location, project size and type (not
one size fits all)
• Include climate in existing activities (e.g. Risk screening in
Design Guidelines, System Planning, EIA process, PPAs, Dam
Safety, Risk Sharing Mechanism) to make it climate smart,
rather than stand-alone
• Invest to learn: monitoring, research and pilots, to improve
future decisions and planning
15
Divas B. Basnyat and Dibesh Shrestha, 10 Mar 2021Thank you!
Divas B. Basnyat, Ph.D.
divas@ndri.org.np
divas.basnyat@gmail.com
Dibesh Shrestha, M.Sc. Middle
dibeshshrestha@live.com Marshyangdi
HEP
NDRI Water and Climate Program: https://ndri.org.np/project_cat/water-climate-program/
Weather Generator Tool: https://ndri.org.np/ourproject/weather-generator-and-climate-change-
scenario-generator-for-climate-risk-assessment/
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