To save the Tarai, save the Siwalik

I was born and raised near Sanguri Danda in eastern Nepal, and it was only later that I found out that the hills were called the Chure.

And it was still later that I learnt that the Chure is also known as the Siwalik Range, the southernmost and lowest fold in the Himalaya bordering the Tarai plains — the geologically and ecologically fragile hills made up of uplifted sediments with only a thin layer of topsoil. 

I have walked in the Siwalik in eastern Nepal, and have often wondered where the name comes from. And no one else seemed to know either, so I did my own research.

The term Siwalik appears to have been first used in a paper published in 1836 in the 19th Volume of Asiatic Researches, Calcutta with its Latin title, Sivatherium giganteum. The authors asked a holy man in Haridwar the native name for the hills directly to the north, and he replied that it was Shivalaya, Shiva’s abode.

The researchers rendered that as Sewalik, and a component of the sub-Himalaya. Later, the spelling changed to Shivalik, and Siwalik today. The Siwalik ridge forms the Nepal-India border wherever there are Inner Tarai valleys like Chitwan and Dang, but elsewhere is the watershed for cities like Janakpur, Birganj, Biratnagar, Bhairawa, Nepalganj and Dhangadi.

The orogenesis of the Siwalik range is closely tied with the collision of the Indian and Eurasian plates that began more than 50 million years ago. Rivers flowed down to the Tethys Sea separating the two converging landmasses, and as the Himalayan mountains were uplifted, these rivers which later became the Ganga, Brahmaputra and Indus cut passages through them. 

There was a lot of volcanic activity due to the subduction of the Indian plate, and remnants of these can be seen in Mt Kailash and other mountains. At different periods after that, the greater Himalaya was uplifted, and the Mahabharat foothills after that. 

About 15 million years ago, some Himalayan rivers were blocked by upliftment and the sediments deposited there turned into sandstone, claystone, conglomerate or shale. Then the most recent tectonic activity in the Himalaya uplifted these sediments to form the Chure-Siwalik range.

The Siwalik is only about 120m elevation in the east, but rises to 1,970m in the west, extending parallel to the main Himalayan chain. The Siwalik ecosystem's services to the plains downstream is vital to the Tarai’s rivers and water supply. But the degradation of the Siwalik due to unregulated mining, deforestation, and road construction increases risk of disastrous floods in the Tarai as well as districts downstream in India. 

There have been government programs including the Presidential Chure Tarai-Madhes Conservation and Development Board, but these have been inadequate or ineffective in slowing the destruction. 

Most of the government’s efforts at restoring the Chure ecosystem concerns forestry and not holistic watershed management. There are some 48 rivers that originate in the Siwalik, but most are dry for 9 months in a year and flow only during the monsoon.

The 2021 census records show that 53% of Nepal’s population now lives in the Tarai, and the populations of the 21 districts bordering the Siwalik are also rising. This translates into increased deforestation to make way for agriculture or new settlements, and unmanaged road construction. 

Women from Saptari district in Madhes Province marched 25 days to Kathmandu, and have been demonstrating at Mandala in Kathmandu against the degradation of the Siwalik. They held a rally last week, with slogans like “Give us water", "Stop wildfires".

Bijaya Singh Danuwar, who did a PhD on the Chure watershed, Members of Parliament Pradip Paudel who is now Health Minister in the new government and Amresh Kumar Singh, former minister Julie Mahato, as well as former minister Prabhu Sah have all raised the destruction of the Siwalik and its impact on the Tarai in Parliament. 

There has been scant attention in the media about the rallies, and the federal, provincial and municipal governments are not showing much concern about the wanton destruction. 

The provinces and municipalities directly downstream from the Siwalik are the ones which should be most concerned because they will be the ones more directly affected. Or is there just too much vested interest with contractors?  

Kamal Maden is a botanist and biodiversity researcher.