Nepal
is exposed to most disaster types ranging from
earthquakes, floods, landslides, droughts, storms,
avalanches, hailstorms, fires, epidemics and
ecological hazards. A wide range of physiological,
geological, ecological, meteorological and demographic
factors contribute to the vulnerability of the
country to disasters. Major factors contributing
to disasters are rapid population growth, slow
economic development, a high degree of environmental
degradation, fragility of the land mass and
high elevation of the mountain slopes .
Earthquakes:
Nepal lies in a region
of high seismic activity. Earthquakes with magnitudes
of 5 to 8 on the Richter scale have been experienced
throughout the country and 279 earthquakes with
epicenters in Nepal and magnitudes above 3.9
have been recorded so far. The country's high
seismicity is related to the presence of active
faults between tectonic plates along the Himalayas,
mainly in the main boundary fault and the main
central thrust. Chains of active faults run
for around 100 km, interrupted by inactive sections.
There are also active faults in the lower Himalayas
and along the southern slope of the Siwalik
range. One main reason for Nepal's vulnerability
to earthquake is the poor construction of public
buildings and house especially in densely populated
areas like Kathmandu.
Floods and Landslides:
Floods and landslides
are often interrelated in Nepal. Some landslides
are triggered by riverbank erosion, and some
flash floods are aggravated by landslides in
the areas adjoining riverbanks. Both these phenomenon
occur during the monsoon season. Glacial lake
outburst floods are common in the Himalayan
region, and are triggered by a wide range of
hydrological, geological and seismic factors.
Disastrous flash floods usually occur in Nepal
when landslides or debris block a river for
several hours and the water is then releases
suddenly, inundating the adjacent area downstream
in a rapid and turbulent manner. Continuous
heavy rainfall may also cause flash floods in
many rivers originating in hilly regions. Flash
floods may also be caused by an avalanche, snowstorm
or cloudburst.
A significant number
of landslides occur each year, roughly estimated
to over 12,000. Various natural and man-made
factors contribute to the high incidence of
landslides. Natural factors include steep slopes,
undercutting of their banks by incised rivers,
weathered, fractured and weak rocks in the mountains,
high rainfall and seismic activities. Man-made
factors responsible for landslides in the country
are intensive deforestation, improper agriculture
and irrigation practices, overgrazing on the
slopes, quarrying for construction materials,
and construction of infrastructure beyond the
bearing capacities of the hill slopes, Landslides
frequently occur in the monsoon season following
an earthquake in the previous year.
Fires
Most fires occur during
summer, particularly in the Terai region when
the temperatures are high and strong winds occur.
Some of the reasons for the fire outbreaks are
poor use of fire, for cooking and other purposes
and lack of adequate fire safety measures. Forest
fires are also common in the hilly areas of
Terai forests.
Nepal has had a history
of severe droughts and famines too. Other disasters
include epidemics such as measles, cholera,
encephalitis, dysentery and diarrhoea, and storms.
Main source:
Russell,Nicholas. Acharya, Madhu Rahman
and Pant, Ram 1990. "Nepal Country Study
" in Disaster Mitigation in Asia and the
Pacific published by ADB.
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