GUWAHATI: Even as Silchar deals with one of the worst floods in its history, a researcher of Geological Science of Gauhati University (GU) believes this is the perfect time for high-resolution flood inundation mapping and identifying the vulnerable areas.
“This has to be done at peak flood level,” Dr Porag Phukon, Professor of Geological Science at Gauhati University, told EastMojo.
Dr Phukon, who has been conducting a study on Silchar floods and landslides, said the state government should commission a precision-contour survey and integrate it into the town master plan.
“The authorities should identify the areas above 1989 flood level or better still, above 1929 flood level, to place the strategic establishments, including electricity control rooms,” Dr Phukon told EastMojo.
In his study, Dr Phukon also suggested restoring Rangir Khal, one of the major canals of the city, to its condition pre-1965, dis-incentivising people from filling up wetlands and encouraging rainwater harvesting to help during such crises of power and water supply disruptions.
He also stressed the need for developing a policy and enforcing it under the Disaster Management Act to prohibit people from occupying the flood-basin areas like Mahisa Beel, which can act as a very effective flood cushion.
Meanwhile, the Assam State Disaster Management Authority (ASDMA) on Friday deployed two drones in Silchar for flood-inundation mapping and providing relief materials in inaccessible areas.
Assam chief minister Himanta Biswa Sarma, who conducted an aerial survey on Silchar on Thursday, said, “This is not a natural calamity, but a man-made flood. The dam bank has been destroyed, and then videos were circulated to stake the the damage claim.”
Dr Phukon said: “It was an avoidable situation with some application of mind by authorities concerned. This amount to criminal negligence due to which Silchar residents are subjected to this horrendous situation. There must be a thorough enquiry, and people responsible for this should be booked.”
Information in the public domain shows that the Bethukandi embankment breach is a man-made one, cut by local people to drain out spill-over water from the Bethukandi area back into Barak after the flood in May. This, however, remained unplugged, making way for the monsoon-surged Barak water to quickly fill the Marisa bil area, which caused the deluge in Silchar.
“Therefore, it is a pertinent question: despite full knowledge of an impending normal monsoon, why did the authorities fail to take suitable measures to plug the breached embankment effectively? The aforesaid circumstances reinforce the feeling that it is a largely avoidable disaster that the people of Silchar are exposed to. It calls for an inquiry to fix accountability and address the systemic loopholes,” Dr Phukon said.
“This flood has exposed the gross inadequacy in the town planning and disaster management plan. Otherwise, how the electricity control rooms and sub-stations be placed in low-lying areas prone to flood?” Dr Phukon questioned.
“Barak water level falling from a maximum of 21.59 m to 21.45 m on Wednesday night, but still flowing more than 1.6 m above the danger level. If it remains above danger level for the next few days, water through the breached embankment at Bethukandi will further increase the inundation in Silchar,” Dr Phukon mentioned.
The Silchar town in South Assam is presently witnessing massive flooding that started on June 18, just a month after the first wave of floods. The second wave of floods came quickly, ravaging most parts of this vibrant town, causing property loss and acute suffering to the people.
The electricity supply has been shut down as the power control rooms and substations are submerged, and there has been no water supply for the last six days.
“Location of Silchar within a large loop of Barak River from Uttar Krishnapur in the upstream to Ramnagar and the highly dynamic erosion-prone nature of the river itself makes Silchar more exposed to flood hazard,” he said.
“However, the presence of the embankment system provided a sense of relief to the town dwellers although, at the same time, dependence on the embankment only increased the vulnerability because these engineering interventions often yield to the high floods, resulting in damage of serious proportion concentrated in areas of the breach. They are also vulnerable to human-mischief damage intentionally caused by people,” he further said.
During the peak of the first wave of flood on May 18, the Barak River level at Silchar stood at 21.46 metres, against the Central Water Commission (CWC) danger level of 19.83 metres.
“In the current wave, data available in the public domain shows that the highest water level of Barak at Silchar was 21.59 metres on June 21, and sharing a falling trend with 21.50 metres on Thursday afternoon. Notably, the Barak basin has a total geographical area of alone 39000 sq km spread over the states of Manipur, Mizoram, Assam, Meghalaya and Tripura,” Dr Phukon further said.
The north bank tributaries: Jiri, Chini, Madhura, Jatinga, Arang Larang and Kalainchara drain from the Dima Hasao and Jaintia Hills. They have a high gradient, and water accumulation into Barak from the rivers are comparatively faster, often resulting in flash flood condition, he said.
South bank tributaries: the Sonai-Rukni Ghagra, Katakhal, Aholeswari and Longai mostly have their source region in Mizoram, while the Barak upstream of Lakhipur has its catchment areas in Manipur, he further said.
“Therefore, rainfall in Manipur, Mizoram Dima Hasao and Jaintia Hills contribute towards flooding in Barak valley. This year, however, intense rainfall was recorded in Dima Hasao and Jaintia Hills in May, causing widespread landslides and flooding, against a low to deficit rainfall in other parts of the Barak watershed upstream of Silchar. This ensured that Karimganj and Hailakandi districts largely escaped the of flood,” Dr Phukon said.
“The present phase of the flood is due to the very active monsoon that set in Northeast since June 1, bringing in record rainfall in many parts of Assam and Meghalaya, including Silchar witnessed a record single-day rainfall of over 450 mm on June 18. As such, the river system, which was already in spate from the pre-monsoon rain quickly raised beyond the danger levels and resisting in the consequential flooding,” Dr Phukon also said.
“Therefore, it is no wonder that Silchar town has always been vulnerable to flood. But what surprised me this time is the magnitude: flood waters reached almost every part of the town within a short time. Surely it is not an urban waterlogging phenomenon or a simple spill over above the embankments,” Dr Phukon further said.
The genesis of this flood in Silchar lies in a breach in the embankment near Bethukandi eastward and upstream of Silchar through with the Barak River shaded a part of its water into the vast wetland around Mahisabil-Bethukandi-Berenga area, he said.
Dr Phukon said that a huge part of water overwhelmed the Rangir khal, an arterial channel that comes out of Mrisa bil and flows through the southern part of Silchar into the Ghagra River and water spread through the low-lying areas in and around Malini bil.
The constricted Rangirchal from encroachment and heavy settlements in the low-lying areas resulted in a quick rise in water level, which initially remained confined to the eastern and southern part and then pushed back northward eventually engulfing almost the entire town by June 20 evening, he added.
Disaster management involves not only post-disaster relief and rehabilitation but also planning and pre-emptive measures. The present reaction-centric approach to disaster management must change into a proactive one with science-based research and planning.
“The gaps must be identified and ensure that lessons learnt from this year are effectively utilised to build a more disaster-resilient society by integrating disaster management plan into the development plans,” he added.
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