The webinar entitled “Real-time Flood, Landslide Monitoring and Innovations (Application of Remote Sensing and UAVs)” was organized jointly by DPNet-Nepal and Practical Action Consulting on 25th February 2021. The program was initiated with the chairing of Mr. Ram Prasad Bhattarai, Vice Chairperson of DPNet-Nepal and objectives sharing by Dr. Raju Thapa, General Secretary of DPNet-Nepal. Altogether 85 participants joined the webinar.
Dr. Prem Bahadur Thapa, Director, TU-QAA Centre, Tribhuvan University shared the presentation entitled "Landslide early warning and application of Remote Sensing/GIS techniques". In his presentation, he covered the EWS used in Nepal Himalaya and how remote sensing and GIS is used for the data acquisition process, analysis for risk reduction process by evaluating the hazards. The presentation included the spatial occurrence of landslides, risk awareness control measure and mapping techniques. The map shared included both earthquake and landslide induced landslides. Landslides are more in Central Nepal and Far Western parts has faced comparatively low landslides. He also shared examples of some prominent big landslides. Furthermore he shared the development of early warning system in Nepal. He shared that landslide early warning is a new concept and it is still being explored for making it low cost technology. He also shared the example of use of EWS in the community. Similarly, his presentation included the application of remote sensing and GIS: mapping and database development analysis and risk reduction strategies-importance of remote sensing and GIS for landslide investigation. He also shared the high resolution image to show the landslides. The process of remote sensing for the data base development of landslides and delineation of landslides features. GIS based approach to extract the landslides map, maps of landslides triggered by extreme weather events and Gorkha Earthquake 2015. He concluded his presentation summarizing the use and application of early warning system, remote sensing and GIS.
Ms. Sristy Maharjan, Hydrologist Engineer, Department of Hydrology and Meteorology delivered the presentation entitled "Role of DHM in real time flood monitoring". In her presentation she shared the Principal Activities of DHM in Flood Monitoring including the establishment and operationalization of flood forecasting stations and upgrade them with real time telemetry system, providing weather forecast information, develop river flow forecasting models for major rivers of Nepal, establish flood early warning systems on major flood prone rivers of Nepal. The important activity is to work with wider stakeholders in coordination for reducing the flood risk. She also said that information source is most important in flood monitoring. The information received from the hydrological and meteoroidal stations (telemetric and manual) is analyzed and shared with the general public. She briefly shared about the evolution of Flood Monitoring and EWS in Nepal. These days we have automatic flood stations which provides the real-time information in 5 minutes time interval. The rainfall also provides the real-time information of water level and velocity sensor also provides the real-time information. There are 172+automatic rainfall stations and automatic 101+ water level stations in Nepal. The data received is monitored, analyzed and flood early warning is done. Furthermore, her presentation also included the hydrological models and Flood Early Warning System and its Effectiveness in Nepal. As a way forward she stated that DHM needs to work on urban flooding, study of Flash Flood and its Model Development, Strengthening bilateral cooperation with China and India to reduce the impact of flood and inundation etc.
Mr. Alberto Muñoz-Torrero Manchado, PhD Student, University of Geneva (Practical Action Consulting team) presented the Landslide trends in western Nepal. An analysis of climatic and anthropogenic drivers over three decades. In his presentation he shared that the previous studies deals with the landslides casualties and landslides frequency due to climate change and some due to anthropogenic factors, but the role is not so clear yet. He stated that the inventory of 26350 landslides were classified as shallow landslides and deep seated landslides. Similarly, he shared the high resolution landslide inventory was necessary to perform correlation to annual dating of landslides, for that an Arc GIS tool box was developed that used Landsat imagery. This tool is able to recognize sudden change. With this tool more than 8778 single events landslides were annual dated from the period of 1992 to 2018 and the correlation was formed with the climatic variables ERA 5 analysis data was used. Strong correlation (r=0.74) was found of Shallow landslides with total monsoon precipitation. Strong correlation (r=0.68) was found of shallow landslides with 10days cumulative precipitation. Highest correlation (r=0.77) was found of shallow landslides with warm monsoons followed by especially rainy monsoons. The correlation with the climatic variables was found much stronger in the North West part of study area may be due to the influence of anthropogenic drivers. For this population growth from the year 2000-2018, agriculture crops increase from the year 1992-2018 and road density was analyzed. He concluded the presentation stating that the climatic conditions of the previous monsoon can have an important when warm monsoons are followed by particularly wet monsoons leading to highest correlations with shallow landslides. Marked spatial variability in the strength of these correlations has been revealed, in which the remarkable demographic development seem to act as a key factor.
Major Discussion Points
• Where should our local government bodies contact if they want to install LEWS? EWS installation is done by NAST, so the local government can contact the Technology Sales in Lazimpat Kathmandu and buy device.
• When and where this technology was tested in Nepal? What are the limitations for application of this technology Nepal? Technology was tested in Gorkha district. Limitations are there are so many landslides, so we are using in major landslides only.
• Need to integrate such technologies and tools findings in formulating municipality/Rural municipality DRR plan formulation. But, this is not adopted. We must consider in hazards risk analysis.
• There are several studies related to landslides risk and vulnerability. Is there any platform where the data and information related to landslides risk and vulnerable assessment are archived for easy access? Documents are not confined in one single platform but organizations like ICIMOD, NAST are trying to compile such documents.
• I think there is still confusion around who should actually own the Landslide EWS? Is it DHM, DMG or other agencies? Owner should be one platform, organizations like DHM, DMG, NDRRMA, and ICIMOD should come together in such platform.
• If quake shakes the land then LEWS system will send SMS? When there is vibration and stretching, there is the possibility of SMS.
• How much can one device coverage of landslide area? This device covers one single landslides and adjoin areas.
• What are the approaches DHM been adopted in monitoring of the services once sensor system does not work in extreme weather system/power dysfunction time/maintenance of real time instruments? Actually we have manual stations near real time stations, so if the system is down then we rely on the manual data which is provided by our gauge readers. Also, we analyze the situation of the present station by comparing the data of u/s stations or nearby stations
• May be we should consider the historic river course for the flood polygon River changes it course in time course, At present right branch Karnali river is flowing in the path back to 1990s.
• Strong correlation between cumulative rainfall and shallow landslides is found generally in Nepal Himalaya cumulative rainfall is correlative with deep seated landslides, which is interesting in the research.
Mr. Ram Prasad Bhattarai, Vice Chairperson of DPNet-Nepal, thanked, resource persons, PAC and participants for their valuable time. He also thanked Atuallya Foundation for providing the zoom service for organizing he program virtually.