Western Disturbances & Precautionary Measures

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TOPIC:

General Studies 1: Important Geophysical phenomena

General Studies 3: Disaster management

What are Western Disturbances?

• Low-pressure areas embedded in the Westerlies, the planetary winds that flow from west to east between 30°-60° latitude.
• Western disturbances are formed naturally. They originate in the Mediterranean region and travel over Iran, Iraq, Afghanistan and Pakistan to enter India loaded with moisture, where the Himalayas obstruct them, causing rain and snow in western Himalayas. The snow adds to the glaciers which provide water to India’s major perennial rivers.
• They usually bring mild rain during January-February, which is beneficial to the rabi crop. Considering that wheat is one of the most important Rabi crops, which is the staple diet of people in this region, winter showers contribute to meet India’s food security.
• Associated with cloudy sky, higher night temperatures and unusual rain – Excessive precipitation due to western disturbances can cause crop damage, landslides, floods and avalanches. Over the Indo-Gangetic plains, they occasionally bring cold wave conditions and dense fog.

Disastrous Western Disturbances

In the past few years’ western disturbances have been linked to disasters such as the cloud burst in Leh in 2010, the floods and landslide in Uttarakhand in 2013 and the excessive rain in Jammu and Kashmir in 2014.

A study by the Indian Institute of Tropical Meteorology (IITM), Pune, has directly linked western disturbances to global warming. Researchers say global warming is impacting air currents and causing freak weather events.

• Pronounced warming over the Tibetan plateau in recent decades has increased the instability of the Westerlies and this has increased the variability of the western disturbances.
• According to the study, the western Himalayan region has seen a significant rise in surface temperatures since the 1950s.
• Observations from the area show a significant increase in precipitation in recent decades.

Precautionary measures

Tackle lack of Awareness

• Usage of Digital India programmes to let people know about the current situation and give warnings well before in hand.
• Social Media helps in sharing the message – making more and more people aware about the situation.

Private Sector Participation

• Government should welcome private sector’s participation in designing and implementing policies, plans, and standards

Technology backed decisions

• Mapping of the storms and proper dissemination of information is crucial.

Community Participation

• A strong, aware and involved community is the first step towards disaster resilient communities.

Note:

There are two phenomenons responsible for winter rainfall in India – Western Disturbances and Retreating monsoon.

Retreating Monson – As ITCZ shifts towards south in the winter season, the monsoon starts retreating. Retreating monsoon winds capture some moisture from Bay of Bengal and cause rainfall on Tamil Nadu coast.

Connecting the Dots

1. What are the reasons of winter rainfall in north western states of India and southern India? Examine the measures to be taken during an unforeseen disaster because of these geographic phenomena.
2. How does western disturbance originate? What effects does it have on Indian agriculture?