Soil Erosion a Serious Concern in the Koshi Basin


The high rate at which soil erosion is taking place in the Koshi Basin of Nepal is a serious concern. Soil erosion impacts not just the fertility of agricultural lands negatively, but also the habitats of fish and other species by causing sedimentation in streams and rivers, and clogging waterways. 

The entire Koshi Basin in Nepal lost an estimated 40 million tonnes of soil between1990 and 2010, according to a study conducted by the Koshi Basin Programme at the International Centre for Integrated Mountain Development (ICIMOD) ( The study, supported by the Australian Government’s Department of Foreign Aid and Trade (DFAT) through Sustainable Development Investment Portfolio (SDIP), made efforts to fill the information gap on erosion patterns and dynamics from 1990 to 2010 using geospatial technology.

Published in 2016, the study showed that the soil loss rate estimated was 22 million tonnes per hectare of barren land per year, with 18 million tonnes in 1990 and 15 million tonnes in 2010. In addition, the total soil loss from agricultural land was estimated to be 10 million tonnes in 1990 and 14 million tonnes in 2010. An estimated 39 million tonnes of soil was lost in 1990 and 42 million tonnes in 2010. 

Identifying soil loss areas is crucial for planning effective interventions at the ground level in the most erosion-affected areas. Erosion priority areas can be determined for planning and implementing conservation measures and erosion management in Nepal, where there is huge loss of arable land due to soil erosion.

Land cover management approaches such as gully plugging, afforestation of degraded land, improving infiltration through construction of pits, and crop management for vegetation cover, among others, can be implemented in fields on hillslopes, or at the watershed scale in the future.   

Studies have shown land degradation, sedimentation, and ecological degradation tend to increase as a result of inappropriate land use and management practices. Soil erosion is contributing to substantial changes in basin hydrology and inundation in the transboundary Himalayan river basins. 

Initiatives are needed to help increase awareness among farmers and are crucial to identifying the best options for farming practices to reduce soil loss from cultivated land and provide support for the implementation of appropriate measures.