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Rising Monsoon Intensity in Western Ghats
Context:
A recent study by researchers at the Central University of Kerala (CUK) has uncovered a significant increase in monsoon rainfall in the Western Ghats over the past 800 years.
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- By reconstructing Indian monsoon patterns spanning the last 1,600 years, the study provides valuable insights into long-term climatic variations in the region.
- The findings highlight historical climate patterns in the Western Ghats and emphasise the urgency of proactive measures to address challenges posed by an intensifying monsoon cycle.
- The long-term increase in monsoon intensity could be linked to the rising frequency of extreme rainfall events in recent years.
About Western Ghats
The Western Ghats, also called the Sahyadri Hills, is a 1,600 km (990 mi) long mountain range running parallel to the western coast of India. It spans six states: Gujarat, Maharashtra, Goa, Karnataka, Kerala, and Tamil Nadu, covering an area of approximately 160,000 km² (62,000 sq mi).
Features
- Geography and Topography: The range starts near the Tapti River in Gujarat and extends south to Kanyakumari in Tamil Nadu. It forms an almost continuous chain of mountains with an average elevation of 1,200 m (3,900 ft). The highest peak is Anamudi in Kerala at 2,695 m (8,842 ft).
- Major gaps include: Palghat Gap (Kerala) Goa Gap and Shencottah Gap. The Western Ghats meet the Eastern Ghats at the Nilgiris.
- Hydrography: The range acts as a major watershed for India, feeding rivers like the Godavari, Krishna, and Kaveri. These rivers drain nearly 40% of India’s land area. Most rivers flow eastward due to the slope of the Deccan Plateau. Smaller streams drain westward into the Arabian Sea.
- Climate Influence: The Western Ghats block rain-bearing monsoon winds from the Arabian Sea, causing heavy rainfall on the western slopes and creating a rain shadow effect on the eastern side.
- Biodiversity: Recognised as a UNESCO World Heritage Site in 2012 for its ecological importance. It is one of the world’s eight “hottest hotspots” for biodiversity.
- Geology: Geologic evidence suggests formation during the breakup of Gondwana in the late Jurassic and early Cretaceous periods. The rocks are primarily Cenozoic in age.
- Environmental Significance: The Western Ghats are vital for:
- Water resources through river systems and reservoirs.
- Climate regulation via monsoon interaction.
- Biodiversity conservation due to its unique ecosystems.
- Conservation: Here are the main committees involved:
- Western Ghats Ecology Expert Panel (WGEEP):
- Established: 2010
- Western Ghats Ecology Expert Panel (WGEEP):
- Chairperson: Prof. Madhav Gadgil
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- Purpose: To assess the ecological status of the Western Ghats and recommend measures for its conservation.
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- Key Recommendations:
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- Proposed that 64% of the Western Ghats be designated as Ecologically Sensitive Zones (ESZ).
- Suggested the establishment of a Western Ghats Ecology Authority to manage conservation efforts.
- Recommended strict regulations on developmental activities in sensitive areas, particularly in ESZ 1, where activities like mining and dam construction should be halted.
- High-Level Working Group (HLWG):
- Established: 2012
- Chairperson: Dr. K. Kasturirangan
- Purpose: To review the recommendations made by the WGEEP and provide a balanced approach to conservation while considering development needs.
- Key Recommendations:
- Recommended designating only 37% of the Western Ghats as ecologically sensitive, a significant reduction from the WGEEP’s suggestion.
- Proposed a framework for sustainable development that allows for economic activities while protecting biodiversity.
Western Ghats and Indian Monsoon
The Western Ghats, a mountain range running parallel to the western coast of India, plays a pivotal role in shaping the Indian monsoon system.
Role in Monsoon Dynamics
- Moisture Trapping: The Western Ghats act as a barrier to the moisture-laden southwest monsoon winds coming from the Arabian Sea. These winds rise along the steep slopes of the mountains, cool down, and result in heavy rainfall on the windward side. This process creates a tropical monsoon climate along the western littoral. The forests of the Western Ghats contribute significantly to rainfall through evapotranspiration, accounting for up to 25% of the rainfall over peninsular India.
- Rain Shadow Effect: On the leeward side (eastern slopes), a rain shadow effect occurs, leading to significantly lower rainfall. This influences vegetation and climate, with scrublands dominating these drier regions.
- The western slopes receive annual rainfall ranging from 2,000–3,000 mm, with local extremes up to 10,000 mm. In contrast, the eastern slopes average about 1,000 mm.
- Active and Break Periods: The monsoon alternates between active periods of heavy rainfall and break periods with mini-droughts. During these breaks, moisture from the vegetation of the Western Ghats contributes up to 50% of rainfall over regions like Tamil Nadu.
