Land Degradation Problems of Nepal
Land Degradation
Almost all types of land degradation exist in Nepal. However, soil erosion and flooding are the major types of land degradation processes prevalent in Nepal. Based on the land system inventory information the extent of land degradation has been broadly estimated as follows (Sthapit, 1994):
A. Soil Erosion
Due to steep slopes and intense monsoon rainfall, soil erosion mainly by water, is the major land degradation process prevalent in Nepal. Almost all parts of Nepal are affected by water induced surface soil erosion, mass movement (slope failure, landslides and rock fall) and riverbank cutting. Some areas are affected by deposition and water logging. The extent of area mainly affected by riverbank cutting and gulling is about 16398 sq. km., slumping and gulling is about 4244 sq. km. mass wasting (slumping, landslides rockfall and avalanches) is about 116566 sq. km. About 4249 sq. km. of land is affected by wind erosion.
  • Loss of topsoil results in the decline of soil fertility.
  • Mass movement of slopes, particularly landslides and debris flows, causes large-scale destruction of productive land, irrigation systems, trails, roads and villages.
  • High sediment loads in rivers reduce the useful storage capacity of man-made reservoirs and cause silting of irrigation canals and damage to turbines and water control structures.
  • Sedimentation, in conjunction with peak discharges, results in abrupt channel changes; these changes may cause complete loss of fertile farm land due to deposition of eroded material or slumping of river banks and, in some cases, destruction of human settlements and loss of life.
B. Flooding
Intense rainfall is the main reason for flooding during the monsoon season in the low lying valleys and Terai plains. The area affected by the floods is estimated to be about 8987 sq. km. These floods damage the fertile plains by scouring and sediment deposition.
C. Water logging
Water logging is a problem during the monsoon period in depression of the Terai region and valleys. The area affected by water logging during the monsoon is estimated to be about 7297 sq. km.