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

4

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.

5

Evidences of CC in Nepal: Expected change in avg. daily max temp.

(Kathmandu valley; 2060)

2oC rise in temperature – South-Western corner

6

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

7

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

8

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

10

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.

11

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

12

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: shrestha_h@hotmail.comhari@nec.edu.np