ALL ABOUT CYCLONES: How cyclone track forecasts can change dramatically and how climate change maybe impacting them.

 We have been tracking the storm in the Bay of Bengal for several days now (as we normally do) and have been posting updates in our WhatsApp Group 'Hazard Alerts'.
On 26Nov2024, the forecast from IMD clearly said that the storm would intensify into a CYCLONE

This was changed and on 28Nov and the storm was expected to remain a 'DEEP DEPRESSION' and make landfall on 30Nov2024 as a 'WELL MARKED LOW' (see below)

The forecast was revised the next day and the track showed the storm intensifying into CYCLONE 'FENGAL'on 29Nov2024.
The latest forecast track from IMD of 'FENGAL' together with WARNING no '3' from JTWC is reproduced below.

The tracks from IMD and JTWC seem to coincide.
I am also posting an article from today's Statesman on how climate change maybe impacting cyclones in the Bay of Bengal

Praful Rao
SaveTheHills
savethehills@gmail.com
9475033744

Media coverage of our Memo on the Teesta valley disaster problem

On 18Nov2024, we had couriered the hard copies of our memo requesting urgent mitigation action in the Teesta valley in the few dry months we have before the monsoons again wreak havoc in 2025.

 'The Hindu' is an old and prominent national newspaper and I am very glad that they carried the Teesta Valley GLOF disaster story almost in its entirety:

(Link: https://www.thehindu.com/sci-tech/energy-and-environment/teesta-valley-disaster-glof-2023-sikkim-west-bengal-act/article68885161.ece)
Subsequently, we emailed the memo to Mr Rajendra Singh, Head of Dept NDMA and Mr D Nariala (IAS), PS of Disaster Management Department, Govt of W Bengal.

Affected citizens of Teesta Bazar blocking the road in protest against Govt inaction at Teesta on 22Nov2024.

Praful Rao
SaveTheHills
9475033744
savethehills@gmail.com

Community-Led Call to Action: 290 Signatures urging Immediate Disaster Mitigation in the Teesta Valley submitted by Darjeeling Himalaya Initiative and SaveTheHills

 

The following memorandum signed by 290 persons from Kalimpong, Darjeeling, and Sikkim has been submitted by Darjeeling Himalaya Initative and SaveTheHills to the Chairs of the NDMA, SDMA W Bengal and SDMA Sikkim:
_______________________________________

The Teesta Valley GLOF Disaster of October 2023: Impacts and Urgent Mitigation Needs Ahead of the 2025 Monsoons.

The Glacial Lake Outburst Flood (GLOF) and the subsequent hydro-power dam breach in the Teesta Valley in October 2023 brought widespread devastation, leading to tragic loss of life, severe damage to livelihoods  and assets as well unaccounted ecological devastation across Sikkim and West Bengal.

The disaster caused significant destruction to the National Hydroelectric Power Corporation’s (NHPC) infrastructure, agricultural land, forests, riverine ecosystems, transportation routes, and even critical military installations (Much of the devastation caused by the GLOF is documented in SaveTheHills’ blog http://savethehills.blogspot.com) Yet, despite the scale of the disaster, the response from state and central authorities have been inadequate, especially long term rehabilitation and restoration interventions at the relief, infrastructure and ecological level.
To further elucidate, we cite the case of fifty six families in the Teesta Valley (Kalimpong district)  who were displaced by the floods in Oct2023 and still continue to reside in relief centres. For these people who depended on the river for their survival, displacement has worsened their economic stability, and every day existence becomes a struggle for survival. Prolonged uncertainty worsens their mental distress, highlighting the urgent need for targeted interventions to restore their houses and livelihoods.
NH10, the lifeline of Kalimpong and Sikkim remained perilously unstable for much of the monsoons season and diversion of traffic from Sikkim via alternate routes added avoidable burden on transport services, infrastructure as well as the communities along the route.These vulnerabilities were exposed again almost throughout 2024 monsoon season and has severely reduced the tourist traffic to the region impacting  the economy of the Sikkim and Darjeeling Himalaya.

With only six months remaining before the 2025 monsoon, there is an urgent need to implement both structural and non-structural mitigation measures throughout the Teesta Valley. Effective action now can significantly reduce the impact of future floods, as such the implementation of these measures both in Sikkim and West Bengal in the valley is a vital necessity.
Central assistance will be imperative simply because the scale and complexity of the problem cannot be tackled at the state level.
The important issues at hand are listed below:

The Case for a Joint Sikkim-West Bengal Committee on Teesta Valley Flood Management

The October 2023 GLOF was one of the most severe glacial floods in the history of the Himalaya, affecting both Sikkim and West Bengal and needs to be responded to at a landscape level that is inclusive of both states. Each monsoon season, the Teesta River poses serious threats to both states, making collaborative management of the river and its surrounding regions essential.
A joint committee from both the states could address common issues and implement coordinated disaster management strategies that benefit both states.

Formation of an Expert Task Force

A dedicated task force of experts, drawn from geo-hydrology, environmental science, engineering, and sociology, should be formed to tackle the many challenges brought about by the GLOF. This task force must develop a comprehensive action plan that includes technical, financial, and social solutions for restoring and fortifying the region.

Structural Mitigation Measures

Construction of Embankments, Protection Walls, and Barriers

Embankments and barriers are urgently needed in low-lying, high-risk areas to prevent river overflow into settlements. Populated areas in the valley which are particularly vulnerable to flooding such as  those below the Teesta bridge along the Darjeeling-Kalimpong road, must be identified and remedial engineering solutions applied.

Channeling the River Flow

The natural flow of the Teesta River was disrupted by debris buildup from the GLOF, leading to riverbank overflow. The river must be re-channelized to prevent further damage to urban areas and infrastructure. Experts in fluvial geo-morphology and hydrological engineering can assist in deepening, widening, and redirecting the river to safer channels. NHPC’s technical expertise can be instrumental in this effort.

Road Engineering and Restoration

NH10, the key highway linking Siliguri and Gangtok, suffered extensive damage during the GLOF, resulting in economic losses and supply chain disruptions. Immediate restoration of this critical artery must be prioritized, along with repairs to alternative routes that have also deteriorated due to increased traffic and monsoonal impacts.

Bridge Repair and Reconstruction

The destruction of bridges in Sikkim and West Bengal has cut off many communities, hindering both economic activity and disaster relief efforts. Repair and reinforcement of these vital structures must be completed before the next monsoon season.

Reinforcement of Evacuation Centers and Relief Camps

Many evacuation centers and relief camps need urgent repairs and enhancements, such as backup solar power, to ensure they remain operational in the event of future emergencies.

Non-Structural Mitigation Measures

Early Warning Systems (EWS) and Communication Networks

Installing automated flood early warning systems (FLEWS) that deliver real-time alerts through sirens and mobile networks is crucial. Backup communication methods, such as ham radios and walkie-talkies operated by trained personnel, should also be implemented to ensure effective communication during emergencies.

Land-Use Planning and Zoning

Certain low-lying areas will remain high-risk zones even with structural protections in place. These areas should be designated for potential evacuation and resettlement of at-risk communities. Adequate compensation as decided by the expert group should be provided to affected victims and necessary support given to those relocating.

Public Awareness and Community-Based Disaster Risk Management (CBDRM)

Community preparedness is essential to build capacities and resilience during disasters. Awareness campaigns should educate residents on flood preparedness, evacuation procedures, and available insurance schemes. Additionally, evacuation drills must be regularly conducted to ensure communities can respond swiftly during emergencies.

Post-Disaster Financial Recovery Support

To aid in economic recovery, education on flood insurance and financial aid should be provided to residents and businesses, ensuring they have the tools to rebuild after a disaster.

Aggressive Afforestation Program

The GLOF caused widespread destruction of forests along the Teesta Valley. An aggressive reforestation initiative is needed to restore the valley’s ecosystem, prevent soil erosion, and help regulate the river's flow.

Conclusion

By implementing these crucial structural and non-structural mitigation measures, the Teesta Valley can be better prepared to withstand future monsoonal floods, protecting both lives and livelihoods. Urgent and coordinated action in the coming months is essential to prevent another disaster on the scale of the 2023 GLOF. The time to act is now, before the monsoons of 2025 arrive.

________________________________

We will submit the Memo to other officials as well.

Our thanks to all those who volunteered in making this community initiative possible

Praful Rao
Darjeeling Himalaya Initiative & SaveTheHills
9475033744

Roshan Rai
Darjeeling Himalaya Initiative
9932024812

The challenge of integrated natural hazards for continued sustainable development in the Himalayas - Dr Malay Mukul, IIT Bombay

CURRENT SCIENCE, VOL. 127, NO. 9, 10 NOVEMBER 2024 1005
CURRENT SCIENCE
Volume 127 Number 9 10 November 2024
EDITORIAL

During the last decade, developmental activities have in-creased progressively in the Himalayas in response to the increase in population and the need for better infrastruc-ture. Defense requirements along the Indo-Tibetan border have also necessitated the improvement of road and rail connectivity in the Himalayas. Tourism has also flourished as more and more people travel to the Himalayas from the plains. Dams have been built on the Himalayan rivers to generate hydroelectricity to meet the increasing demand. All these essential developmental activities have strived to be sustainable. Nevertheless, there is a growing realization that natural processes can throw an unexpected spanner in the works of the most carefully thought-out development projects. Landslides, glacial lake outburst floods (GLOFs) and earthquakes can strike the Himalayas at any time and place, and understanding the Earth’s processes that trigger these natural hazards is crucial to preventing loss of life and property during these events. The Earth’s processes typically operate over geological time scales but have the potential to strike anytime they cross the tipping point. The focus has to shift from disaster management to disaster prevention to avert increasing loss of life and property.
Climate change has resulted in concentrated rainfall over short intervals from the earlier norm of distributed rainfall in time and space. This results in flash floods and slope failure that can combine to form devastating mud- and debris flows. The warming climate has also accelerated the melting of Himalayan glaciers, resulting in glacial retreat and the formation of large glacial lakes at their terminus. These lakes are surrounded by glacial moraines that can easily breach due to their low mechanical strength by excessive rain, slumping of moraine material into the lake, or even earthquakes. Any such event will result in an extreme debris-laden flash flood in the river valleys downstream destroying everything in its way. Two such events are fresh in our memory. First is the 4 October 2023, North Bengal–Sikkim extreme GLOF event that killed more than 100 people, changed the entire morphology of the Teesta River valley and destroyed a dam. Second is the 30 July 2024, rainfall-induced flash flood in Wayanad, Kerala. Although not in the Himalayas, the villages of Punchirimattam, Chooralmala and Mundakkai were destroyed killing more than 420 people during this event.
Landslides also accompany these events adding to the destruction inflicted by the flash flood. In the Himalayas, fluvial terraces and past landslide debris in the valley are soft targets for erosion by the flash floods because they consist of unconsolidated and incohesive material. River terraces are popular sites for the construction of buildings and camp sites as they offer flat top surfaces in sloping mountainous terrains. In extreme-event flash floods, these are the first to be destroyed, as evident from multiple videos on social media where riverside constructions topple and assimilate into the river. Toe erosion, or the erosion of the base of existing and previously stabilized landslides, dur-ing GLOF events can re-activate them.
Landslides exist as a separate, independent hazard in the Himalayas too. Steep slopes, weak rocks and high rainfall combined with human activities lead to multiple Himalayan landslides. Landslides can dam rivers and create lakes that can eventually burst through the dammed river and cause a flash flood downstream. Like the river terraces, the landslide debris spreads out in the valley and provides flat surfaces for construction. Therefore, they are frequently used to develop residential and commercial real estate or other essential infrastructure similar to the river terraces. Landslides or avalanches into glacial lakes filled to the brim due to retreating and melting glaciers also cause overflow of the glacial lakes and flash floods downstream. The 4 October 2023, North Bengal–Sikkim GLOF event was attributed to the landslide of a large chunk of lateral moraine into the South Lhonak Lake. Therefore, land-slides and GLOF flash flood events can also be integrated hazards and be the cause and the effect of the other.
The other looming hazard in the Himalayas is the seismic hazard. Decades of work have revealed the presence of a major fault under the Himalayas, the Main Himalayan fault, which extends from the Tibetan Plateau to the Gan-getic plains. The fault slopes north and transitions from a near-surface brittle deformation regime to a ductile regime at depths greater than ~15 km. As evident from the Global Positioning System (GPS) measurements, the Himalaya is being continuously transported from north to south along this fault. In the ductile regime, this motion does not cause earthquakes. At the brittle-ductile transition, this motion is arrested because of friction along the fault typically absent in the ductile regime. This causes strain accumulation in the region and is characterized by micro- to moderate-earthquakes and maximum vertical uplift. Bends in the Main Himalayan fault near the brittle-ductile transition also cause strain accumulation. This region is located in the central part of the Himalayas and is likely where large and great future earthquakes will originate. For example, the magnitude 7.3, 2015 Kathmandu earthquake originated in this region. Large and great earthquakes are also known to trigger multiple landslides. Studies also reveal that many Himalayan glacial lakes are full due to climate-change-induced enhanced melting of glaciers. Therefore, there is a high probability that future large and great earthquakes will also trigger coeval landslides and GLOF events.
Therefore, the worst-case natural hazard scenario in the Himalayas will involve coeval earthquakes, landslides and GLOF events. This is what we need to be aware of and prepare for. Himalayan natural hazard models must inte-grate seismic, landslides and GLOF hazards for any reali-stic forecast of disasters and disaster preparedness. The first step is the integration of all known information and scientific insights. For example, we know that large earth-quakes will originate in the central part of the Himalayas and affect the Higher Himalayan lakes initiating GLOF events. We can also identify the most vulnerable landslide-prone regions should these events occur. The disaster-pre-paration strategies should include the possibility of all three hazards occurring together in the Himalayas. Also, a purely statistical approach to hazard estimation may not be sufficient and realistic. For instance, the basis of seismic zonation in India is the frequency of large earthquakes. Zone 5, with the maximum frequency of large earthquakes, is recognized as the most hazardous. However, recent studies make Zone 4 more hazardous as strain has accumu-lated here since the last major seismic event but not been released. Similarly, the frequency of landslides separates more landslide-prone areas from others. However, no strategy exists to forecast the initial landslide occurrence in a region where no previous landslides have occurred. New studies and strategies that account for the Earth’s processes in addition to statistics must be evolved to understand and prevent loss of life and property in future natural disasters.
Sustainable development under such a scenario must recognize and understand the collective hazard to the fullest extent possible. A wealth of scientific data and insights relevant to these hazards are available. For instance, although earthquakes cannot be predicted in time, we know that the Himalayan earthquakes will originate in the central part of the Himalayas. This insight can help save lives if the buildings and infrastructure in that part of the Himalayas are designed or reinforced to withstand large earthquakes. Similarly, all Himalayan hydroelectric pro-jects must factor in the high seismic hazard and GLOF sce-narios. The Himalayas are also riddled with fault zones that concentrate weak rocks in them. These fault zones are also likely to nucleate landslides. Therefore, identifying such fault zones can potentially locate future landslides. Using existing scientific knowledge and insights to miti-gate or prevent future disasters is the key to sustainable development in the Himalayas. The most tragic disasters are those where red flags existed but no timely action was taken to prevent the disaster. The Himalayan seismic haz-ard is a potential example of such a situation. Studies over two decades have red-flagged several parts of the Himala-yas as areas where strain has accumulated over centuries without any release through large earthquakes. The next large earthquake in these areas will cause large-scale loss of life and property. The time to minimize or prevent this is now. We should not wait for the event to happen and merely disaster manage its aftermath.
Finally, the lessons of disasters that have already occurred must not be forgotten. For example, the extreme events in Wayanad and North Bengal–Sikkim have explicitly esta-blished the boundaries of the river basin. The river deposits associated with these events will be vegetated and provide flat surfaces where it might be tempting to build in the future. The river basin must be left alone and everything inside moved to higher and safer grounds. If these lessons are ignored, the disasters will keep repeating. The magnitude of the disasters will keep increasing as the population in-creases and more lives and infrastructure come in harm’s way. Our survival may ultimately depend on how well we recognize the multiple red flags in nature and get out of harm’s way when there is still time. Maintaining maxi-mum sync and harmony with nature during developmental activities is the only sustainable way forward. We must embrace this or be prepared to suffer the consequences.

Malay Mukul
Indian Institute of Technology-Bombay,
Mumbai 400 076, India
e-mail: malaymukul@iitb.ac.in

Published by
Praful Rao
SaveTheHills
savethehills@gmail.com
9475033744