Destruction of paddy filed.

Late Kartik Pegu, grandfather of Bipin Pegu of Jiyadhal Chariali village under Dhemaji Revenue Circle of Dhemaji district in northeast Assam prepared his own burial site during early 1970s on the bank of Jiyadhal River.

The site, a paddy filed, has been owned by the Patir family of the village near the railway bridge over the river. Kartik Pegu was buried there when he died in 1976 and a tombstone was built on his memory.

After that in 1985 Bilapson Pegu, Bipin’s father, too was buried on the same site and another tombstone was placed in his memory close to that of Kartik Pegu. Now 47-year-old Bipin Pegu, a college graduate and a local peasant with three children wishes him to be buried on the same plot of land when he dies.

But on the evening of September 16, 2019, his wishes for final rest close to his near and dear ones were shattered when Jiyadhal River suddenly surged with overflowing water submerging the tombstones of Bipin’s immediate ancestors. He has never seen them being under water from the nearby river in his lifetime so far.

The flash flood of Jiyadhal on September 16 breached the Jiyadhal Station Road connecting Dhemaji Engineering College in Tinighariya village. Apart from this the swollen river this time destroyed vast acres of agriculture land with newly growing paddy in half a dozen villages—all lived by indigenous Mising community, Schedule Tribe group in Assam.

Bipin Pegu infront of his ancestral burial site

Green paddy fields at Azarbari, Kekuri Miri, Narabeel, Panitola, Hesuli Pathar and Tegjuri Koch Pathar Part-I villages from the slopes of the sub-Himalayan hills of Arunachal Pradesh to the National Highway-15 turned white overnight with sand and silt deposited by the overflowing river.

Besides leaving the peasants with the loss of this year’s harvest, the abnormality of Jiyadhal has also threatened the family of Bipin Pegu of losing their burial site.

A river synonymous with flood and bank erosion

Dhemaji district of Assam till very recently was known as the sorrow of the state as it was devastated by the flood of its rivers every year to a great extent. All the major rivers in the district, originating in the hills of Arunachal Pradesh to its north swell dangerously during monsoon every year as heavy rain lash the region.

The flood disrupted road communication in Dhemaji very badly besides causing tremendous losses to the agriculture—the only economic activity of the district. Among the rivers and tributaries Jiyadhal was the symbol of a unique phenomenon of flood related destruction.

Jiadhal, a northern Sub-tributary of the Brahmaputra originates in the sub-Himalayan mountains of Arunachal Pradesh at an altitude of 1247m above the M.S.L. After passing through a narrow gorge in Arunachal Pradesh, the river enters the plains of Assam in Dhemaji district where it flows in braided channels.

The river is known as ‘Kumotiya’ from the railway line to Gogamukh-Ghilamara PWD road in Lakhimpur district wherefrom it is called ‘Sampara’. The river finally debouches into the Brahmaputra near Selamukh in Lakhimpur district. But after construction of the embankment over the Kherkutiya Suti of the Brahmaputra, the river falls into the Subansiri River.

Site of the frequent cloudburst in the hills

The whole sub-basin of Jiyadhal experiences heavy rainfall annually. The average annual rainfall as recorded at Dhemaji is 3,500 mm (SANDRP-2013). It carries heavy silt load from its 1346 sq. km catchment area during the rainy season and deposits them on its bed in the plains resulting in the considerable rise of its riverbed.

Jiyadhal is known for frequent changing of its course and this caused devastating flood in 1984, 1988, 1989, 1992, 1994, 1997, 1998, 2002, 2007, 2009, and 2011 bringing disasters to this area creating a widening of its courses to a cobweb like phenomenon in Samarajan.

Till early this year, a stretch of about 3 kilometres on NH-15 between Bordoloni and Dhemaji was a driver’s nightmare due to the curious course of Jiyadhal. The entire area along with the railway track and bridge with vast paddy fields had been the centre of a unique concentration of unpredictable course of Jiyadhal (called Kumotyia in that area) river making it un-motorable.

For almost two decades people were compelled to cross this stretch during monsoon sometimes on boats, over makeshift bamboo bridges or through waist deep water because of the abnormality of the river. It is only in early 2019 that this stretch on NH-15 in Samarajan was turned hospitable with as many as eight big and small RCC bridges.

The Northeast Frontier Railway too constructed two steel bridges in close proximity in Samarajan in its upgraded Rangia-Murkongchelek tracks. It has been estimated that till 2011 Jiyadhal floods severely affected about 85 villages and 300 hectares of crop land, including a large area with standing crops (Saikia, 2013).

Climate change impacts

The Jiadhal River is a classic example of a flashy river and produces floods with a sudden, high discharge over a short time interval (a few hours to a day) and with a high sediment load and debris.

The flashiness of the river can be mainly attributed to high rainfall in the upstream hilly catchment and the basin as a whole, and the steep piedmont zone between the foothills and the flat alluvial plains through which the river flows. Flash floods in this river are generally triggered by continuous heavy rainfall or extreme rainfall events such as cloudbursts (Saikia, 2013). When Bipin Pegu was talking about the inundation of their family burial site near the railway bridge of Jyadhal, there was sounds of thunder in the blue hills of Arunachal Pradesh just 10 kms away under a bright sun.

Bipin and some other fellow villagers pointed towards the gorge in the hills that looked foggy—the emerging point of Jiyadhal in West Siang district of Arunachal Pradesh. The foggy foreground among the blue hills in that bright sunny day meant raining which would bring more water to Jiyadhal passing through the villages up to NH-15 in Dhemaji.

Though these villagers have been experiencing the flood with sediment load and debris in Jiyadhal in last four decades, a delay has been witnessed in the surge of water in last couple of years. This time too, Jiyadhal swelled in mid-September—almost two months later the usual annual monsoon.

Sand deposit on paddy fields

Cloudbursts in the Himalayas have been attributed to rising temperatures due to climate change. While global temperature is recorded to have increased by about 0.8°C in recent decades, the increase has been greater in regions at higher altitudes like the Himalayas where the decadal temperature rise is higher than the global rate of rising temperatures.

According to a study published in the journal Elsevier in January 2018, the reported rate of warming over the eastern Himalaya was over 0.6 °C/100 year during 1901–2002.

“The Tibetan plateau and Brahmaputra basin showed the largest increase during spring season with 0.2 °C/decade during 1971–2005 over northeast India and warming of 1.6°C across the north-western Himalayan region during 1901–2002,” the study says.

According to Sandipan Mukherjee, scientist at GB Pant National Institute of Himalayan Environment and Sustainable Development, the warming has wreaked havoc on the monsoonal patterns in the Himalayas resulting in increased moisture levels.

The thunder heard from Tinighariaya village off the Jiyadhal river is nothing but cloudbursts—an extreme amount of precipitation, sometimes accompanied by hail that normally lasts no longer than a few minutes, but discharges a large amount of water in a small area.

For the villagers Azarbari, Kekuri Miri, Narabeel, Panitola, Hesuli Pathar, Tegjuri Koch Pathar Part-I on the either side of Jiyadhal in Dhemaji district, the September 16 was an another havoc by the river lasting for few hours but robbing their dreams of a golden harvest this year.

The deposition of coarse sand and silt particles on the inundated plains by the flash flood reduces soil quality making the land unfit for agriculture. About 5.72 square km of land in more than a hundred villages has been gravely affected by sand casting by Jiyadhal floods (Deka, 2008).

Study indicates that in the last four decades (1973–2010), the area affected by sand has increased by 18% resulting in the 34% decrease of both summer and winter crops. Like in the last four decades, this time too this has emerged as the most serious impact of flash floods in the Jiadhal River catchment.

Besides destroying the economy and livelihood activities of the indigenous communities, the Jiyadhal floods have taken the lives of 48 people between 1989 and 2002 (Hazarika, 2010). All these have made us to note that Jiyadhal is sending a climate change SOS which we must heed.

So far, the Jiyadhal floods have been treated as a mere bank protection issue as its surging water breached its embankments at different places in the last four decades. Now it is high time that it should be dealt from a climate perspective also.

Sazzad Hussain is a freelance writer and independent researcher based in North Lakhimpur, Assam.

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