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| ||Mountain ecosystems|
Natural resources in fragile mountain ecosystems have been under severe strain for the past few decades due to their over-exploitation, caused by the need to meet the ever-increasing demands for livelihood.
In recent years, the growing concern over environmental degradation of mountainous ecosystems has gradually placed mountain issues in the environmental and political agenda.
Land, water, and vegetation are the most vital resources for the survival of humankind, and need to be managed efficiently.
Sustainable management of these natural resources is the biggest challenge of these ecosystems, and is essential in providing food and feed for human and livestock, and environmental security.
For the sustainable development of an area, identification of the most frequent hazards that took place over the past few years in the area may play a vital role in assigning priorities.
Deforestation is the changing of forests into other land use and forest degradation. It is one of the biggest socio-economic and environmental problems of Nepal.
Massive deforestation in the history of Nepal has led to degraded, thinned forests. Soil degradation covers soil erosion and soil deterioration. Landslides are common and occur naturally in Nepal, but are influenced by human impact as well.
Deforestation, intensified cultivation, extension of agriculture to marginalised areas, and steep slopes have increased soil erosion, depleted soil fertility and the productive capacity of the land. Soil erosion has further led to the deposition of sediment in tanks and reservoirs that has reduced storage capacity and increased flooding and landslides, as well as loss of arable land in low lying areas.
Nepal’s forests have been under a degradation process throughout history. Among the most important reasons are government policies which led people to clear forested areas due to tax exemption during the 18th and 19th centuries.
Trees used for fodder
Another huge impact on the forested area in Nepal is the massive population growth which increased dramatically over the past years. Tourism has also led to clear-cuts of forested areas, and has made the situation even worse.
The following tables show that the situation of deforestation could be improved by several activities. Among them, inhabitants of the Chitwan National park are now performing guided tours of the forest, which helps protect the forests and generates an income for the villagers.
| ||Annual forest change rate|| |
|1990 - 2000||- 92 000 ha/yr||- 2.1%|
|2000 - 2005||- 53 000 ha/yr||- 1.4%|
|Forest areas|| ||Other wooded land area (open forest)|| |
|1990||4 817 000 ha||1990||1 800 000 ha|
|2000||3 900 000 ha||2000||1 753 000 ha|
|2005||3 636 000 ha||2005||1 897 000 ha|
A landslide is a geological phenomenon which includes a wide range of ground movement, such as rock falls, deep failure of slopes and shallow debris flows, of which the action of gravity is the primary driving force .
Landslides can occur for different reasons:
- Erosion by rivers, glaciers, or ocean waves.
- Rock and soil slopes are weakened through saturation by snowmelt or heavy rains.
- Earthquakes create stresses that cause the slopes to weaken.
- Volcanic eruptions produce loose ash deposits, heavy rain, and debris flows.
- Vibrations from machinery, traffic, blasting, and even thunder may trigger failure of weak slopes.
- Excess weight from accumulation of rain or snow, stockpiling of rock or ore, from waste piles, or from human-made structures may stress weak slopes to failure and other structures.
- Groundwater pressure acting to destabilise the slope.
- In shallow soils, the removal of deep-rooted vegetation that binds the colluvium to bedrock.
HimalayasEnvironmental problems in the HimalayasUrbanisationThe Himalayan regionNepal areaTibet area
ExercisesHimalaya - WorksheetLandscape units of NepalUrbanisation – 40 years of urban development of LhasaUrbanisation – Detection by means of delineation of the city perimeterLandslide detection in Langtang Himal
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