Nepal Hazard Risk Assessment - Asia-Pacific Gateway for Disaster ...

Nepal Hazard Risk Assessment
EXECUTIVE SUMMARY
Background
Nepal has witnessed several major natural disasters in the last two centuries. A number of those
highlighted are the 1833 and 1934 earthquakes, the Koshi floods and the GLOF events in the higher
Himalayas. Apart from these major disasters, Nepal also faces frequent landslides during monsoon
season, thunder lightning, storms and regular seasonal flooding in terai areas. The combination of these
multiple hazard events poses a severe threat to national development processes. The national government
is committed to take the necessary measures to avert these threats in the development process. In line
with this commitment, the Ministry of Home Affairs, Government of Nepal initiated the process of
developing a national hazard and risk profile for the country. The project was financially supported by
the Global Forum of Disaster Risk Reduction and the World Bank. The project was implemented by the
Asian Disaster Preparedness Center (ADPC), the Norwegian Geotechnical Institute (NGI) and the
Center for International Studies and Cooperation (CECI). The project was technically supported by the
International Institute of Applied System Analysis (IIASA). The project was largely implemented by
consultation and coordination with all focal government departments including the Department of
Hydrology and Meteorology, the Department of Mines and Geology, the Department of Health Services,
the Department of Agriculture, the Department of Water Induced Disaster Prevention and the National
Planning Commission. The project process was further coordinated with several focal agencies,
departments and institutions.
Project Objectives
The project objectives include the development of a synthesis report on Nepal's major hazard risks by
carrying out a review of existing vulnerability and hazard reports, studies, analyses and assessments at
the national and sub-national levels; an overview presentation of the vulnerability assessment for the
country; the development of a detailed economic analysis using the loss probability modeling of Nepal’s
risks in conjunction with projected economic losses from forecasted hazards; and the mapping of high
risk geographic regions.
Scope of the Project
The scope of the project included collecting and analyzing existing data and reports of historical losses
due to catastrophic events in Nepal; mapping the natural hazard risks for Nepal; detailing exposure to
droughts, floods, landslides, earthquakes and other hazards; analyzing and quantifying the projected
losses in absence of mitigation investments; and identifying possible information gaps and outlining the
need for further analytical work to develop a comprehensive quantitative risk assessment for Nepal.
Project Methodology
The methodology has been compartmentalized into several sections. The methodology is presented in a
flowchart as presented in Figure 1. The project methodology incorporated data collected from existing
hazard and vulnerability studies, risk assessment reports, disaster databases, the national economic assets
database etc. In addition, hazard mapping was conducted by modeling for earthquakes, floods,
landslides, epidemics and drought. The vulnerability functions of various assets were characterized with
respect to each hazard, as well as the estimation of associated risk and the economic implication of
disasters. Lastly, national disaster risk reduction recommendations were evolved. The linkages between
various components can be seen in Figure 1.
The project began by studying a number of past disasters and their impacts in Nepal. Thanks to a strong
national commitment to alleviate disaster suffering, the impacts of several types of disasters are reducing
everyday. However, there will always exist the impending threat of major disasters in the future. There
are several important sectors which govern the national growth of Nepal on which disasters can have
serious impacts. It is thus necessary to assess such impacts on these identified sectors. Key sectors such
as housing, health, education, transportation, agriculture, tourism, mines and query, power, industry,
irrigation, fisheries and trade are considered in this report. However there remain several other important
sectors in Nepal which could not be considered in this project due to the unavailability of data and time
constraints.
The hazard assessment and hazard mapping has been carried out for earthquakes, floods, landslides,
droughts and epidemics. A variety of well established scientific tools and techniques have been used to
assess the hazards and mapping accordingly. For earthquakes, hazard mapping is done for 50 year, 100
year, 250 year and 500 year return periods. For flooding, the most flood prone rivers and catchments is
considered in the flood hazard assessment. The flood hazard mapping presents flood severity in terms of
inundation depth and area. It was carried out for the Kamala, Kankai, Bagmati, Tapti, Tinau, Babai and
Narayani rivers and considered 10 year, 25 year, 50 year and 100 year return periods. The landslide
hazard mapping is carried out according to two triggering factors, namely earthquake-induced and
rainfall-induced. Landslide prone areas are classified as low, moderate and high prone areas. The
drought hazard mapping consisted of an analysis for the whole of Nepal using the standard precipitation
index. Drought hazards were classified into moderate, severe and extreme conditions. Furthermore, the
drought assessment was carried out for four distinct seasons, namely winter, pre-monsoon, monsoon and
post-monsoon. Hazard assessment and mapping is conducted for several epidemics and diseases
including leprosy, malaria, tuberculosis (TB), sexually transmitted infections (STI), diarrhea, acute
respiratory infections (ARI), filariasis and kalazar, typhoid, influenza and ARI, gastroenteritis and
hepatitis.
The hazards assessment concludes with a multi-hazard assessment and mapping based on two hazard
severity scenarios. Scenario one considers a 500 year return period earthquake, earthquake-induced
landslides, rainfall-induced landslides, 10 year return period floods, droughts occurring in the winter
season, and health hazards susceptibility. Scenario two considers a 250 year return period earthquake,
rainfall-induced landslides, 10 year return period floods, droughts occurring in the winter season, and
health hazards susceptibility. Scenario one reveals that three districts Sindhuli, Salyan and Rolpa are
having five types of Geological, Hydro-meteorological hazards. Ilam, Lalitpur, Dhading, Kaski,
Syangja, Mustang, Rukum,Makawanpur, Dang, Jajarkot, Dailekh, Kalikot and Accham are prone to four
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