Concerns raised over decimation of green cover in Cauvery basin: NGT issues notice to southern states

A recent report found green cover has declined to 15,345 sq km from 28,154 sq km over past 50 years

By Coovercolly Indresh
Published: Sunday 14 January 2024
Kabini River, one of the major tributaries of Cauvery river in southern India. Photo: Coovercolly Indresh

The National Green Tribunal (NGT) has served notices to Karnataka, Tamil Nadu and Kerala governments, based on a report by the Indian Institute of Science (IISc) that has highlighted the massive reduction of green cover in the Cauvery basin over the past five decades. 

The notices, directed to the Union ministry of environment, forests and climate change, the director general of forest survey of India and other authorities concerned, was taken up suo motu by Justice Prakash Srivastava.

According to the IISc report, the Cauvery basin has witnessed a staggering loss of 12,850 square kilometres (sq km) of green cover between 1965 and 2016. The NGT expressed deep concern over the extensive agricultural and horticultural activities covering 73.5 per cent of the Cauvery basin, with only 18 per cent remaining as forested areas and dense forests limited to just 13 per cent of the region.

The report highlighted that natural green areas have significantly diminished, declining from 28,154 sq km to 15,345 sq km over the past 50 years. In Karnataka alone, 57 per cent of the green cover, equivalent to 9,664 sq km, has been lost. Tamil Nadu has seen a loss of 29 per cent (2,905 sq km) and Kerala has lost 27 per cent (279 sq km) of its green cover during the same period.

The alarming situation extends to prominent national parks and wildlife sanctuaries in the Cauvery valley. The forest area in Bandipur National Park has decreased by 15.19 per cent in 50 years, primarily due to development activities and forest fires. Nagarhole National Park has experienced an 11 per cent decline in forest cover due to human intervention and increased horticulture activities.

Similarly, Biligiri Ranganathaswamy Temple (BRT) Wildlife Sanctuary has witnessed a decline in forest cover, with concerns raised about forest encroachment.

The Cauvery Wildlife Sanctuary faces a threat to its forested areas due to population growth and encroachment, resulting in an 18.43 per cent reduction in greenery between 1973 and 2016. Bannerghatta National Park has seen a significant decline in dense forest cover, to 28 per cent in 2016 from 50.40 per cent in 1973, the report found. The expansion of agricultural activities, mining and development projects has exacerbated the pressures on these natural reserves.

Considering the gravity of the environmental impact, the NGT categorised the issue as a matter of environmental law. The Supreme Court has affirmed that voluntary cases can be filed in such instances. 

The states concerned were urged to respond promptly to the NGT and the case will be heard at the Chennai bench of the Tribunal, given its jurisdiction over the matter. The NGT has underscored the urgency of addressing the environmental challenges facing the Cauvery valley and safeguarding its ecosystems.

The Cauvery basin deforestation is mainly caused by illegal tree fellings , wild fire, encroachment and other causes. Moreover, the Cauvery water is being polluted day by day due to letting waste water into river, the report had said.

A study from the Indian Institute of Technology, Bombay (IIT-B) paints a sobering picture, as deforestation in the Western Ghats is draining the lifeblood of water-scarce regions like Tamil Nadu. Disappearing verdant landscapes, robbing monsoons of their power and leaving parched lands in their wake.

The stark reality unfolds across peninsular India, where the majestic Western Ghats, a recognised biodiversity hotspot, have shed a staggering 33,579 square kilometres of green cover since 1920. This translates to a 35 per cent loss, driven by the relentless expansion of plantations, agriculture and the thirst for hydropower dams.

This ecological unravelling isn’t just stealing away vibrant ecosystems; it’s messing with the very rhythms of rain, said the study, published in the journal Geophysical Research Letters in 2018 that unmasked the Western Ghats as silent rainmakers. They influence 25 per cent to 40 per cent of Tamil Nadu’s monsoon bounty between June and September – the same bounty that sustains crucial Kharif crops.

For a state already grappling with water scarcity and inter-state disputes over Cauvery River sharing, this monsoon magic disappearing act is a dire threat.

The IIT-B team’s simulations unveiled a dance of land and weather. Lush vegetation acts as a capacitor, holding onto moisture and releasing it as monsoon clouds gather. This verdant orchestra orchestrates a daily downpour of 3 millimetres (mm) across vast swathes of Tamil Nadu and the Cauvery basin during peak monsoon months. Strip away the green cover and the melody changes to a harsh whisper, with daily rainfall nosediving to a meagre 1mm to 2.5mm.

As trees vanished, a chilling side effect emerged: Rising temperatures. The study revealed a 0.25-degree Celsius increase in surface temperature across Tamil Nadu, fueled by a vicious cycle. Deforestation exposes bare land, allowing more sunlight to bake the earth, leading to increased evaporation and hindering moisture buildup.

To illustrate the chilling impact, the researchers delved into three monsoon-depleted years – 1993, 1999 and 2002. Deforestation in the Western Ghats had sucked away 40 per cent to 50 per cent of rainfall in each of these years across the state. 

There are projects at work trying to safeguard the Western Ghats, including one by spiritual organisation Isha Foundation that has embarked upon large-scale tree planting. ‘Rally for Cauvery’ by the organisation claims to have raised funds for planting over 46 million trees in the Cauvery basin and efforts by the foundation’s leader Sadhguru have garnered celebrity and political support. It has detailed plans to “support farmers in planting 2.42 billion trees through agroforestry” through donations as low as $0.60 per sapling.

However, environmental experts and scientists have raised red flags, casting doubt on the project’s efficacy and long-term impact. Ecologist Shishir Rao criticised the foundation’s focus on tree planting, arguing that it ignored the root causes of the Cauvery’s woes, large dams disrupting water flow and sediment transport.

The 805-kilometer-long Cauvery, once a perennial lifeline for millions, now faces a harsh reality due to multiple pressures, water demand for agriculture, industry and domestic use and frequent inter-state water disputes. This has resulted in prolonged dry stretches, leaving the river gasping for breath.

Afforestation is not the magic bullet for boosting rainfall, according to experts like those at the Ashoka Trust for Research in Ecology and the Environment (ATREE). They pointed to urbanisation, groundwater depletion and existing / planned dams as the true culprits.

ATREE proposed a more holistic approach, emphasising urban pollution control, proper waste management and restoring riparian and floodplain ecosystems. Additionally, adopting sustainable agricultural practices like water-efficient crop selection and drip irrigation is crucial.

Relying solely on captivating solutions without addressing the multifaceted challenges faced by India’s rivers might be akin to chasing a green mirage.

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