- Mention the meteorological factors affecting Indian monsoon.
- Elaborate about how different anthropogenic activities are contributing to vagaries of monsoon.
The Indian Monsoon plays a very crucial role in bringing rains to India, as it causes more than 75% of India’s annual rainfall. Indian Agriculture and hence its economy strongly depend on the monsoon rain. The fate of the Kharif crops depends on the performance of the southwest Monsoon. Interference by humans in the natural landscape and changes made by them to suit their needs (like urbanization, industrialization etc.) leads to disturbances in hydrological cycle of atmosphere.
Reasons behind variability of Indian monsoon due to meteorological factors:
- Variability in the monsoon is caused by several meteorological phenomena such as variable Sea Surface Temperature (SSTs) leading to El-Nino, and La Nina, shifting of ITCZ, movement of westerly Jetstream, differential heating patterns of Tibetan plateau and Indian Ocean etc.
- El-Nino leads to weakening of Indian monsoon.
- La-Nina leads to more rains than normal years.
- If ITCZ doesn’t establish fully above the Tibetan plateau, then monsoon remains weak and abrupt changes occur.
- Strength of monsoon also depends on the shifting of southern branch of the westerly Jetstream to the north of the Himalayas. If the southern branch doesn’t shift to the north of Himalayas, monsoon remains weak.
- South-west monsoon also depends on the Madden-Julian Oscillation (MJO) wave for normal monsoon.
Impact on Indian monsoon due to man made changes:
- Anthropogenic interventions are leading to excessive deforestation, increase in pollution and pollutants, rise of built-up area, global warming, etc.
- Increased availability of pollutants and dust particles are leading to an increase in the number of condensation nuclei, which in turn leads to the urban regions receiving increased rainfall than the rural regions.
- Increased built up area allows increased heating of the surface. This increased temperature causes more evaporation and further affects rain patterns.
- Deforestation also creates an adverse impact on monsoon.
- Destruction of Wetlands : Wetlands help in water purification, flood control, shoreline stability, and act as a carbon sink. Destruction of wetlands such as lakes or ponds in urban areas is one of the major reasons of irregular rain pattern in big cities like Chennai or Srinagar.
- Concrete Use: Use of concrete in urban areas causes poor recharging of groundwater and changes the hydrological cycle of environment which ultimately disturbs the Monsoon system of India.
- Creation of large dams in hilly areas which have changed the ecological flow of rivers is also an example of man-made changes.
Though other reasons like El-Nino, Cloud cover, Differential heating patterns of Tibetan plateau and Indian Ocean also causes the monsoon change, but man-made factors can be easily controlled that are affecting the Indian monsoon badly.