Relationships between landsliding and land use in the Likhu Khola drainage basin, Middle Hills, Nepal

A great deal has been written about the relationship between landsliding and land use change, especially deforestation, in the Himalaya. But few detailed quantitative studies have examined this relationship. The present article reports the results of a 3-year study of landsliding in 4 subcatchments of the Likhu Khola drainage basin in the Middle Hills, Nepal. During the years of study (1991-1993), 381 landslides were noted, the vast majority of which were small failures on the risers of irrigated terraces (khetland). Although significant in terms of labor input, these failures were insignificant with respect to land degradation and overall denudation. Most significant were larger failures on abandoned terraces and degraded forest. it was estimated that the average annual soil losses from the main land uses were 0.48 ton/ha for irrigated terraces, 3.65 ton/ha for rainfed terraces, 1.86 ton/ha for grassland, 0.80 ton/ha for forested land, and 23.95 ton/ha for forest scrub and abandoned land. The combined average erosion rate was 5.55 ton/ha. Thus, deforestation does not necessarily lead to large soil losses from landsliding; much depends on how the land is managed after deforestation.