ENVIRONMENTAL SCIENCE : POLLUTION AND ITS FACTORS 191
- Weather Conditions
Generally, anticyclones are rainless and sky is free of clouds because of the fact that
descending air in the centre of anticyclone is warmed up at dry adiabatic rate due to
subsidence. This causes rise in temperature, which reduces normal lapse rate of temperature,
with the result the stability of air increases resulting into marked increase in the aridity of
air. This is why anticyclones are indicative of dry weather.
- Landslides
Among physiographic units, the two northern units of the Greater Himalayas (7500-
8500m), and the Inner Himalayas (Trans-Himalayan zone), an intervening system of high
plateau and valleys lying between the two great mountain ranges, are considered along with
middle mountains, the traditional centres of population. The upper northern section of these
middle mountains remains largely’ under upper montane forest (2900-4000 m), below which
is the belt of intensive agriculture. Lithology is highly varied, including sedimentary,
metamorphism, and granites. However, there are extensive areas of phyllites and schists;
these are deeply weathered and the prevailing steep slopes render them highly susceptible
to erosion and slope failure (mostly through landslides). Presently, according to gross yet
reliable estimate, the landslides occupy about 1% of land surface in only five central districts
of Himachal Pradesh. They have a total volume of more than 2.2 x 106 m^3 and a mean age
of 6.5 years. This helps to evaluate the denudation rate, which is about 12 mm/year (all
erosive processes). Landslides have about 2.5-mm/ year denudation rates. One of the main
causes of landslides is road construction.
Suggestions
Various studies indicate that for each linear kilometer of mountain road, 10 small to
medium landslides occur. Prior to the 1962 border war with China, the Himalayan section
in India was in most parts accessible only on foot. The shock of the Chinese military
presence, the three India-Pakistan wars of 1947, 1965, and 1971, the continued border
tensions (especially along the Kashmir ceasefire line), and several other problems led to
accelerated construction of up to 10,000 km of highways and connecting roads. The poor
alignment and ill-considered design are causing a total soil loss of 0.199 t of sediment per
linear meter of road per annum. Valdiya (1973) indicated that during the construction phase
an average kilometer of road requires the removal of 40,000-80,000 m^3 of debris. These
enormous volumes are dumped on the roadsides and damage ecologically fragile slopes by
depriving them of natural vegetation and at times destroy the terraces.
QUESTIONS- Write the definition of pollution in your own words and also explain the causes of pollution.
- Explain the types of pollution. Write the precautions to minimize the pollutions (air, water,
social, marine, noise). - What is social water management? Explain.
- Explain the role of an individual in prevention of pollution and how it is possible?
- How we can conduct the pollution case study in a particular area and also explain the
disaster management?