Back to success stories

The Mountains’ Shifting Soils

70% Complete

A new project brings together researchers from China, India, and Nepal to study sediment dynamics in the Koshi basin

Despite their height, the Himalayas are some of the youngest mountains in the world. This brings with it an element of fragility because many of the mountains’ formations have yet to permanently settle. Because of this, the Himalayas are highly vulnerable to erosion, and each year in the Koshi basin monsoon rains wash as much as 135 million tonnes of sediment into the rivers. These rivers, bulging with seasonal glacier and snow melt and rain, rush down to the Gangetic Plains, carrying loads of sediment along with them. The sediment is deposited on the plains’ flat riverbeds, and, over time, these riverbeds begin to rise. This prompts rivers to divert and meander to find new, easier paths, which can be dangerous for nearby communities. Over the past 220 years, the Koshi River has moved approximately 115 kilometres westward. In its wake, it has eroded farmlands, washed away crops, and displaced many people who live on the densely-populated plains surrounding it.

The aim is that the project will not only break new ground of our understanding of erosion and sedimentation processes in the Koshi basin, but also set an example of regional science collaboration on environmental challenges.

In order to better understand the Himalayas’ transboundary geomorphological processes, the Koshi Basin Programme has started an integrated, basin-wide study looking at the causes of land degradation and the impacts of erosion and sediment in relation to water related hazards. The study, which began in 2014 and will continue until 2017, brings together cross-border expertise from the three Koshi basin countries. Using GIS technology, land modelling, and statistics, the Institute of Geographic Sciences and Natural Resource Research, which is part of the Chinese Academy of Sciences, is conducting research on land use and land cover change to understand the relationship between environmental factors and erosion. Researchers from the Indian Institute of Technology-Kanpur are using a landscape evolution model to understand the movement of sediment and its overall relationship with the basin’s rivers, and Nepal’s Department of Hydrology and Meteorology is collecting data from five sediment stations in the upper section of the Koshi basin to analyse erosion processes. The aim is that the project will not only expand the understanding of erosion and sedimentation processes in the Koshi basin, but also set an example of regional science collaboration on environmental challenges.

While the research is still in the early stages, some advancements have already been made. Researchers working on land use have produced a series of maps and an accompanying paper that details soil loss over 20 years, and have marked out conservation priority areas on which to focus future management. These areas are mostly in the hilly and mountainous regions of Nepal and the Tibet Autonomous Region of China.

Taken together, the project’s goal is to create transboundary knowledge around erosion and sediment dynamics in the Koshi basin that will help in designing sustainable management and hazard mitigation plans in the future. Proper management requires an understanding of where sediment comes from and how it is distributed on a basin-wide level. With this knowledge, planners can design stable water channels and dams, promote smart soil conservation practices, and encourage irrigation schemes that lessen erosion and help the region to avoid future disasters.

Partners: Indian Institute of Technology, (IIT-Kanpur, India) ; Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences (IGSNRR, CAS); Department of Hydrology and Meteorology (DHM), Nepal
Project title: A study on sediment dynamics and sediment connectivity in the Koshi Basin: Implications for river hazards (IIT-Kanpur, India); A study on land use change and land cover change, erosion and land degradation in the Koshi River Basin (IGSNRR, CAS); Improvement of discharge and sediment data in the Koshi River Basin (DHM)
Years active: IIT-Kanpur, India: June 2014 – June 2016;
IGSNRR, CAS: July 2014 – June 2016;
DHM: April 2015 – June 2017
Replication and upscaling in challenging mountain environments

Solar pump and water-lifting package of technologies solves irrigation problems

Interdisciplinarity at altitude

Consultative efforts and pilots across the Kangchenjunga Landscape have identified best practices for improved yield, and a shared vision ...

3 Dec 2019 Water
In Search of More Time

Community-based flood early warning systems will help communities in the Koshi basin better prepare for a flood

A New Perspective

Efforts to understand the Koshi basin’s upstream-downstream linkages have the potential to change river basin management In ...

2 Dec 2019 Water
The Changing Times

A study finds that while environmental conditions in the Koshi basin are changing, constraints are keeping communities from fully adopting ...

2 Dec 2019 HI-RISK
Real-Time Flood Data and Science Products Support Flood Monitoring in Nepal

Floods are a major natural disaster aggravating poverty in the Indus and Ganges-Brahmaputra-Meghna (GBM) basins, which is home to over ...

Commitment to Support Integrated River Basin Management in Nepal

Over the course of the next five years, policy and implementation efforts will be made to support integrated river basin ...

Science-based regional collaboration through the Upper Indus network 

Members are presently working on basin level issues focusing on climate change and resilience