Dr. Hari Krishna Shrestha Professor, Nepal Engineering College Workshop on Developing Regional Collaboration in River Basin Management in Response to Climate Change Thimphu, Bhutan December 20, 2013 Flood Management and Climate Change, Nepal
Dr. Hari Krishna ShresthaProfessor, Nepal Engineering College
Workshop on Developing Regional Collaboration in River BasinManagement in Response to Climate Change
Thimphu, BhutanDecember 20, 2013
Flood Management andClimate Change, Nepal
Flood Management ApproachesStructural: Challenging due to non site specific knowledge and many uncertainties, even without climate change
formulas and coefficients based on past experiences of “others”Encroachment and land reclamation followed by “embankment”
Non-structural: getting gradually main streamedImproved drainageLess obstruction to flow during floodAwarenessPreparation and Climate ResilienceEarly warning
Link between Climate Change & Flood Management Parameters in Nepal
• Temperature change impact on GLOF• Precipitation change (Return Period and intensity) of rainfall• Land cover change induced landslide and its impact on river
sedimentation, runoff coefficient & flash flood• Climate change forced change in agriculture in marginal land,
its impact on runoff coefficient, debris flow, river chocking, and flood
• Change in river bed morphology and its impact on flood intensity
• Combined effect of all these CC parameters on flood magnitude
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Infrastructure design parameters related to flood management
❶
❷❸
❶ High Flood Level (HFL): used to set the design height for road, bridge, dyke embankment, spurs, settlements
❷ Scour depth: used to set the foundation depth for bridge, barrage and dyke infrastructure
❸ Width of Waterway: used to define set-back for embankments, dykes, and flood protection infrastructure.
The climate change is impacting these design parameters.
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Evidences of CC in Nepal: Expected change in avg. daily max temp.
(Kathmandu valley; 2060)
2oC rise in temperature – South-Western corner
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Max/Min temperature(Charikot, Dolakha)
Month
Change in Minimum Monthly Temperature
°C (2060)
Change in Maximum Monthly
Temperature °C (2060)
Jan +2.1 +2.6
Feb +3.5 +4.0
Mar +2.8 +3.2
Apr +2.1 +0.7
May +1.0 +1.6
Jun +1.5 +1.5
Jul +1.5 +1.5
Aug +1.7 +1.8
Sep +1.9 +1.8
Oct +2.7 +1.5
Nov +3.1 +1.2
Dec +2.7 +1.9
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Max temp. exceedance curve(Charikot, Dolakha)
Maximum Temp.
exceeded OC
% of Days in Year
Baseline
% of Days in Year
Projected 2060
% change
20 10 35 +25
22.5 4 8 +4
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Flood-based infrastructure design parameters: CC Impact
Seasonal changes in rainfall
• Increase in wet season: too much water• Decrease in dry season: too little water
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Rainfall return periodsKathmandu Airport
Kathmandu One day Extreme Frequency
Return Period
BL (mm)
Projected 2060 (mm)
% increase
25 180 275 5350 200 310 55
100 220 350 59
25 year rainfall of 2060 expected to be higher than current 100 year rainfall.
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Flood return periods
Return Period
Design Flood BL
m3/s
Design Flood 2060m3/s
% 2060
2 799 1254 +57
5 1080 1697 +57
10 1280 1998 +56
25 1589 2388 +50
50 1825 2683 +47
100 2090 2983 +43
200 2350 3289 +40(Shakya, B., 2013)
Projected 2060
Projected 2040
Baseline
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Change in Flow duration/ dependabilityBagmati at Chovar
% Time
Mean Flow m3/s
BL
Mean Flow m3/s2060
% Change
10 60 71 +1820 49 56 +1540 30 32 +760 16 15 -580 6 5 - 15
Increase is wet season and decrease in dry season, exactly what we don’t want.
Increased incidences of floods: more number of floods to manage, each with more potential damage
Consequence
Region YearMahakali-Darchula, Karnali-Bardiya June 2013Khare Khola, Ramechhap; Dholi Khola Ramechhap
May 2013August 2013
Dang, Koshi June 2012Baitadi, Achham, Kalikot, Jajarkot, Rukum, Rolpa, Kaski, Tanahu, Makwanpur, Gorkha, Nuwakot, Saidhuli, Sarlahi, Solukhumbu
June 2011
Dailekh, Jajarkot, Rukum, Palpa, Rupandehi, Parbat, Dhading, Sindhuli, Solukhumbu
August 2011
Seti-River-Khara Pani May 2011Kanchanpur September 2010Dadeldhura, Bajura, Achham, Rukum, Kaski, Illam June-August
2010Koshi Embankment Breach 2008
August 26, 2013, Flow in Dhobi Khola, Kathmandu. CC effect?Photo credit: TL Adhikari
Darchula Flood, Nepal June 17, 2013. CC effect? Source: Onlinekhabar.com
Legal Setup for Flood Management in Nepal
ACTSNatural Disaster Relief Act, 1982Soil and Water Conservation Act, 1982Water Resources Act, 1992Forest Act, 1993Environment Protection Act, 1996Local Self Governance Act, 1998Disaster Management ActRegulationsNational Water Plan 2005National Water Resources Strategy, 2002Water Induced Disaster Management Policy 2006
Institutions Setup for Flood Management in Nepal
Pre During Post
Relief Rehab/Reconstruct
Resettle
Line agenciesDHM DWIDP DSCWM MoFALD MoSTE MoI MoHA MoD
Local Govt.DDC VDC
INGO/NGO Social Organizations Academic/Research Mass Media
Institutions Setup for Flood Management in Nepal
• Project based activities: Multiple Actors– Line Agencies– I/NGOs: ICIMOD, Practical Action, Mercy Corps, UMN,
LWF, UNDP, Action Aid, IFRC, OCHA, UNISDR, World Bank, ADB, USAid, AusAid, DfID,
– NGOs: NRCS, DPNet, SOHAM, CDS, CDRS, NDRI, NCDM, …
Current activities in Nepal to better manage flood and CC impacts
• Mainstreaming Climate Change Risk Management in Development• NAPA/LAPA• Flood Hazard, Flood Vulnerability and Flood Risk Mapping of all 75 districts• Climate Change Coordination Committee, chaired by the Honorable Minister for Science, Technology
and Environment, to provide oversight and guidance for all climate related projects in the country• Pilot Project on Climate Resilience• Building Resilience to Climate Related Hazard• NRRC: National Risk Reduction Consortium
– School/Hospital Safety– Emergency Preparedness and Response Capacity– Flood Management in Koshi; GFDRR: http://www.un.org.np/nrrc/flagship3– ICBDRR/M– Policy and Institutional Support for DRM
• National Strategy on Early Warning for Natural Hazards, DHM, Mercy Corps, Practical Action• Guidelines/Manuals
Environment Friendly Infrastructure Development Guideline, 2013, MoFALD• River training, Peoples’ Embankment• SERVIR (regional-ICIMOD)• Academic: TU, PU/ Nepal Engineering College (DRM) and iWRM, MoE: School curriculum update
Flood Disaster Risk Management (India-Nepal Collaboration)
• Regular data sharing in major river basins
• Early Warning• Success: partial• Challenge: increase
the success rate
Regional Collaboration Issues• Access to data: whose data?• Monitoring: satellite based and ground based• Ground based technicians’ involvement in site specific research• Real time data sharing/Early Warning: easier but are we willing?• Development of mutual confidence• Upstream compensation for downstream benefit: win-win
approach, sounds good, but tactics missing• Development of mutually agreed methodologies for evaluating
different flood management parameters (technical, social, financial, economic)
• Regional Fine-grid Climate Change Modeling
AcknowledgementThe nine slides related to the case studies used in this presentation
are taken from a currently running ADB funded project on Mainstreaming Climate Change Risk Management in Development
under the Ministry of Science, Technology and Environment, financed by the Strategic Climate Fund (TA 7984)
email: [email protected]@nec.edu.np