Dynamic Flood Topographies in the Terai, Nepal; community perception and resilience

Lead Research Organisation: University of Edinburgh
Department Name: Sch of Geosciences


Rivers that discharge from mountain ranges support vast populations that depend on annual floods for irrigation and nutrient supply to crops. The largest population of this type is that of the Gangetic Plains where nearly 10% of the world's population depend on waters from the Himalaya. Much of this area is also characterised by extremely low income levels such as in Uttar Pradesh and Bihar states in India, and in Nepal. Consequently, these regions have long been supported through the UK's overseas aid budget.

Unfortunately, many of the Himalayan rivers are also the source of devastating floods, with effects further compounded where isolated communities, living on the river floodplain, lack disaster risk management and resilience measures. In Nepal, flood disasters were responsible for over USD 130 million losses and nearly one third of all natural disaster-related deaths between 2001 and 20081; this doesn't include the downstream cross-border impact in India. More recent examples include the 2008 Kosi River avulsion that killed hundreds and rendered millions homeless, and the 2013 Uttarakhand floods that killed over 5000 people and is viewed as India's worst natural disaster since 2004. Most of the damage generated by the Uttarakhand floods resulted from major zones of erosion and deposition during peak discharge of the channel; studies by the Edinburgh Land Surface Dynamics group demonstrated that the main signal of change driven by the dynamic nature of the alluvial topography during flooding was broadly predictable. The dangers of changing river morphology during floods has also been highlighted following major earthquakes such as the 2008 Wenchuan and 1999 Taiwan earthquakes where sediment released into the rivers from landslides caused river beds to rise by up to 18 m causing devastating floods in the years following the earthquakes due to re-routing of river courses. The 'seismic gap' left in western Nepal following the 2015 Gorkha earthquake suggests that readiness for a comparable cascade of flood hazards following a major earthquake is imperative for this region.

In this proposal, we aim to build a unique interdisciplinary team based at Edinburgh University combining engineers, geomorphologists, social anthropologists, human geographers and sustainable building designers. This team will rise to the challenge of how academic research can help develop local economies and save lives in response to flooding in the Nepalese plains. We are working closely with the international NGO Practical Action who work with local communities and government bodies to improve resilience. Through a series of workshops in Nepal, we will understand the needs of the communities and the nature of the science that needs to be generated. We will use fieldwork in the region accompanied by the generation of remotely sensed topographic maps to reconstruct past floods, and as input into predictive models. Working with engineers, we will build models that not only predict the passage of flood waters, but also the changing shape of the underlying river bed during these enormous floods. Having developed predictions for future floods, we will also investigate the range of local building constructions that will enable more sustainable flood platforms to be constructed.

This project represents the foundations for the expansion of this strategy into the future with applications all the way along the Himalayan floodplains in collaboration with the range of different ethnic and political contexts.


Planned Impact

The following groups represent the direct beneficiaries of this research:

1. Village Communities of the Terai - The initial impact of floods throughout the plains of the Himalaya is on the low income communities of the Terai. The Dalit and Tharus communities are the most vulnerable group as they live on both sides of the flood plains of the Karnali River in Bardia and Kailali districts. The human development index (HDI) values for Bardia and Kailali districts are 0.466 and 0.46 respectively (Nepal Human Development Report 2014). The HDI scores of Madhesi Dalit and Terai Janajati (indigeneous) are 0.4 and 0.473 respectively which indicate very low level of living standard of these communities. THey will benefit by:

A. A key, long-term goal of this project is to facilitate an understanding of the historical record of flooding over past millenia, and the likely future flood scenarios based on model predictions.
B. Based on this, we plan to use the 9 month grant to generate some synthesis illustrations of flood scenarios that capture the relevant components of the experimental model outputs. These will be iterated in response to community feedback during the second workshop as a means to assess their impact for future development.
C. Through this study, we intend to convey the dangers of generating sediment in the rivers from upstream activities such as road building and changes in land-use.
D. A long-term goal will be to assess whether there are sustainable building techniques that are more readily accessible to the bulk of the community such that every village in the floodplain could build its own platform.
E. As a part of the community engagement, researcher Dingle will train four individuals in suspended sediment sampling procedures using newly purchased sediment samplers (see justification of resources).

2. Karnali-based local NGOs. - The outcomes that will be key for this group are the flood forecasts based on the combined modelling and geomorphic reconstructions. As a part of this we will explore the impacts of inserting embankments alongside the rivers in terms of modifying sediment accumulation and flood risk. An awareness of the fact that future floods will not be in the confines of the historical documentation from the last few decades, and that the most devastating will be those that move beyond the historical. This passage of information will be managed through the network of local NGOs with links to Practical Action in the area. NGO's work in the area is mostly concerned with livelihoods and structural measures such as building culverts, safe ways and safe shelters and helping communities build resilience.

3. Department of Hydrology and Meteorology, Kathmandu - This organisation represents a principle stakeholder in the project. As outlined by Mr. Binod Parajuli in his email' of support - "we actually want to establish a more effective flood early warning system than today... which needs a high resolution DEM (digital elevation model) to develop flood hazard and risk maps, many river cross section and discharge measurements to establish a good flood forecasting model". Additionally, as Sumit Dugar from Practical Action states - "Practical Action has worked extensively on community based flood early warning systems in collaboration with DHM for over a decade and they are our key partners". In addition to supplying the digital topography (WP3) of this area in a simple-to-use format, we will also train their staff to use the ADCP (as in WP4), as it is clear that these techniques have never been used to validate their estimates of flood discharge.
We therefore envisage a strong linkage between Practical Action, the DHM and the new DISTAL project team in developing improved methods and outputs for predictions and for conveying this information to communities.
Description We have been able to demonstrate that the ability to predict flood inundation is very sensitive to the resolution of the digital topography used, and to the mobility of the coarse bedload (pebbles and cobbles). It is also important that changes in the routing of the channels is monitored and updated for ongoing erosion and sedimentation during floods.
Exploitation Route The integration of sediment transport into flood inundation models is very important in these regions at the front of mountain ranges such as the Himalaya. We are trying to convince the Department of Hydrology and Meteorology in Nepal to update their modes which are the basis of their early warning systems.
Sectors Communities and Social Services/Policy



Description We generated a Policy brief in collaboration with the NGO Practical Action that has been passed on to the Department of Hydrology and Meteorology in Kathmandu. We have also discussed various aspects of the development of early warning systems for flooding in these regions that are integrated by Practical Action.
First Year Of Impact 2017
Sector Communities and Social Services/Policy,Environment
Impact Types Policy & public services

Description DISTAL
Geographic Reach Local/Municipal/Regional 
Policy Influence Type Influenced training of practitioners or researchers
Description Multihazard Urban DIsaster Risk Hub
Amount £19,800,000 (GBP)
Funding ID NE/S009000/1 
Organisation Natural Environment Research Council 
Sector Public
Country United Kingdom
Start 03/2019 
End 02/2024
Title NA 
Description NA 
Type Of Material Improvements to research infrastructure 
Year Produced 2017 
Provided To Others? No  
Impact NA 
Title Karnali River Suspended Sediment Sampling 
Description Measurements of vertical sediment grain size, concentration and velocity profiles across the gravel-sand transition in the Karnali River, Nepal. Full descriptions of methodology are available in the Supplemental Material document associated with Dingle, E. H., Sinclair, H. D., Venditti, J. G., Attal, M., Kinnaird, T. C., Creed, M., ... & Gautam, D. (2020). Sediment dynamics across gravel-sand transitions: Implications for river stability and floodplain recycling. Geology, 48(5), 468-472. 
Type Of Material Database/Collection of data 
Year Produced 2021 
Provided To Others? Yes  
Impact These results bring new constraints on channel stability at mountain fronts and indicate that temporally and spatially limited sediment flux measurements downstream of GSTs are more indicative of flow stage and floodplain recycling than of continental-scale sediment flux and denudation rate estimates. 
URL https://zenodo.org/record/4923988
Description DISTAL network 
Organisation Practical Action
Country United Kingdom 
Sector Charity/Non Profit 
PI Contribution Co-authorship of policy brief; co-organisation of two workshops; scientific input on digital topography, flood modelling and Nepalese culture and architecture.
Collaborator Contribution Facilitated communication between us and the Department for Hydrology and Meteorology in Kathmandu; Coordinated workshops and writing of policy brief; Introduced the Edinburgh team to relevant government and community organisations.
Impact Follow-up grant applications to NERC and the GCRF; Very multidisciplinary as they are an NGO, and we are an academic team ranging from geosciences, anthropology, architecture, and engineering.
Start Year 2016
Title LSDTerraceModel v1.0 
Description This software contains a method of objectively identifying floodplains and terraces from digital elevation models based on local gradient and elevation compared to the nearest channel. The method is described in detail by Clubb et al., 2017. The terrace and floodplain code is based on the Edinburgh Land Surface Topographic Tools package. Detailed documentation and tutorials for installation and running the code can be found at http://lsdtopotools.github.io/LSDTT_book/ Use of this software for research should cite: Clubb, F. J., Mudd, S. M., Milodowski, D. T., Valters, D. A., Slater, L. J., Hurst, M. D., and Limaye, A. B. (2017) Geomorphometric delineation of floodplains and terraces from objectively defined topographic thresholds, Earth Surf. Dynam., 5, 369-385, https://doi.org/10.5194/esurf-5-369-2017 
Type Of Technology Software 
Year Produced 2017 
Open Source License? Yes  
URL https://zenodo.org/record/824204
Description DISTAL 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Policymakers/politicians
Results and Impact Workshop in Kathmandu
Year(s) Of Engagement Activity 2017
URL https://distalnepal.wordpress.com/contact/