GLOF Risk Assessment

Nepal

© ICIMOD

In Depth Coverage

Glacial Lake Outbrust Flood Risk Assessment in the Himalayas

The glaciers in the Himalayan region are retreating rapidly due to Climate Change causing formation and rapid growth of glacial lakes. These lakes retained by loose moraine dam are susceptible to outbursts. There have been several such glacial lake outburst floods (GLOF) in past decades and many lakes in the Himalayas are categorized as potentially dangerous. A GLOF event can have serious impacts on the infrastructure, lives and livelihoods of the mountain communities and can have far reaching socio-economic consequences. In the proposed project, we intend to monitor the growth of glacial lake in Poiqu/Bhote Kosi river basin using high resolution SPOT imageries. Dam-break and hydrodynamic models will be applied to study the nature of potential outburst of one most hazardous lake. SPOT imageries and SPOT derived DEMs will be used to provide key parameters and data for the modelling. Furthermore, the images will be used to produce high impact visual materials for dissemination

  • Link With Climate Change

    Open

    The Himalayas are considered to be highly sensitive to Climate Change. The warming rates in the region has been relatively high. The warming in past decades have been found to be progressively higher in the higher elevations (Shrestha et al., 1999, Liu and Chen 2001). The high warming in the region is having profound impacts on the glaciers of the Himalayas. The glaciers of the Himalayas are shrinking at a rapid rate, causing multitude of problems. One of the most visible and tangible impact is the formation, rapid growth and ultimately outburst of glacial lakes (Yamada et al., 1998, Mool et al. 2001). An outburst from the glacial lake can cause a catastrophic flood in the downstream riparian areas.

  • Objectives

    Open

    There are about 200 glacial lakes in the greater Himalayan region, which can burst out any time. There have been about 35 glacial lake outburst flood (GLOF) events in the region in past 4 decades (ICIMOD, 2007). There are indications are the GLOF frequencies have increased in the recent decades and it will further increase (Shrestha and Shrestha, 2006). A GLOF event can have serious impacts in the mountain basins. The rapid waves of water and debris can destroy essential infrastructure, agricultural land, settlement and take high number of human lives. These can serious impact the livelihood of poor mountain communities and also have far reaching impact on the socio-economy of the countries.The objective o f the proposed project is to monitor the development of glacial lakes in the headwater region of the Poiqu/Bhote Kosi River and assess the risk of the potential glacial lake outburst flood in the river basin.

  • Work plan

    Open

    To be developed

  • Schedule

    Open

    To be developed

  • Technical and Scientific Approach & Methods Proposed

    Open

    1. A series of high resolution SPOT imageries will be used to monitor the growth rates of the glacial lakes in the headwaters of Poiqu/Bhote Kosi River basin. Based on the characteristics of the lakes and growth rate the hazard rating of the lakes will be conducted and the most hazardous lake will be selected for further assessment.

    2. The SPOT derived DEM combined with other available information will be used to used to generate the detailed topographic map of the lake.

    3. A damburst model will be applied to study the scenarios of the GLOF. The Outburst scenarios will be routed along the river valley to study the impacts of the flood. High resolution imageries will be used to map the settlements, landuse pattern and infrastructure along the flood path.

    4. A field based socio-economic household survey will be conducted to collect socioeconomic data from the river corridor.

    5. Based on the flood map and socio-economic survey a GLOF risk assessment will be accomplished. The output of the GLOF modelling will be overlaid on the imageries to produce high impact visual products for decision makers. The information generated will be shared with key stakeholders and communities.

  • Results

    Open

    1. A report on scenarios of GLOF including hydrographs, flood arrival time, etc

    2. A report on risk assessment of the study area

    3. A report on socio-economic impact assessment (beyond the time frame of present proposal)

  • Deliverables

    Open

    To be developed

  • Use of Satellite Imagery and GIS Solutions

    Open

    To be developed

  • Local Actions

    Open

    A detailed socio-economic household survey will be conducted in the river corridor. This will include vulnerability and resilience assessment of the communities and assessment of the infrastructure and services to be impacted by the potential GLOF. As the results become available it will be share with the communities. At the end of the project period a local stakeholder capacity building and awareness raising program will be organized.

  • Miscellaneous information / interesting details on project

    Open

    1.This study is perhaps the first of its kind combining state of the art technical methods and social methods2.The study will be a part of larger GLOF and Flash Flood Program of ICIMOD3.The lessons learned from this study will be valuable to conduct similar studies in other basins in the Himalayas and will be used for preparing capacity building materials for wider dissemination.

  • Region Name

    Open
    Poiqu/Bhote Kosi basin a transboundary river basin between China and Nepal (85°40'-86° 20' E 27° 20'-28°40'N)

  • Partners involved in project

    Open
    1. Principle Investigator: Dr. Arun B. Shrestha, Climate Change Specialist, International Centre for Integrated Mountain Development (ICIMOD) Tel +977-1-5003222Email:abshrestha@icimod.orgwww.icimod.org

    2. Mr, Pradeep MoolRemote Sensing SpecialistInternational Centre for Integrated Mountain Development (ICIMOD) Tel +977-1-5003222Email:pmool@icimod.orgwww.icimod.org

    3. Mr. Rajesh ThapaLand and Water AnalaystInternational Centre for Integrated Mountain Development (ICIMOD) Tel +977-1-5003222Email:rthapa@icimod.orgwww.icimod.org

    4. Mr. Sagar Ratna BajracharyaSatellite Hydrology OfficerInternational Centre for Integrated Mountain Development (ICIMOD) Tel +977-1-5003222Email:sagbajracharya@icimod.org