This is why Kerala floods were the worst in a century

Deluge of the century

We can't understand which one is river and which one is road.” That is how Rajesh S, a resident of Chengannur town in Kerala, described the ground zero situation to Down To Earth (DTE) speaking over a mobile phone. River Pamba swelled bringing Chengannur under water. “But we all expected this would happen,” he says. The day the state government decided to open all the dams, Rajesh told DTE, the devastating flood was just a matter of time. As the outside world tracked news of heavy rains for more than a week after August 8, the response was just a habitual disclaimer. For a state living with two monsoons and fighting drought for the last three years with a monsoon deficit ranging up to 34 per cent, it was a respite. Day after day, over 11 days, floods gripped all the state’s 14 districts with an unheard of ferocity. Amateur mobile videos of the destruction started streaming out: hills crumbling down as debris, people being swept away by gushing streams, dams brimming with water and most of the towns and villages filled with displaced people. This was Kerala’s worst flood in almost 100 years.

On August 19, for the first time in the preceding 11 days, satellite images of Kerala captured fractures in the cloud cover. The state government lifted the red alert consequently. The fragmented clouds over the state unearthed the real devastation. Everybody had one question: was it normal?

“It is abnormal but not unusual,” says D S Pai, the head of climate services division of the India Meteorological Department (IMD). Official response is always presented using the tact of terminology. Over 11 straight days of tempestuous rainfall, nearly 25 trillion litres of water fell on Kerala—an area of 38,800 square kilometres cramped with mountain ranges; third-highest population density in the country; and, 44 rivers with 61 dams—with apocalyptic fury.

A ravaged landscape

The state doesn’t have the experience of coping with this scale of damage to life and property—it claims that only 14.52 per cent of its area is flood prone. At the time of writing, the government confirmed 387 deaths. The state government has estimated the preliminary loss at Rs 20,000 crore, which is around 15 per cent of the state’s GDP estimate for 2018-19. According to risk management agency, Care Ratings, floods have affected more than four million people, a significant percentage of them labourers. In August alone, people would lose wages worth Rs 4,000 crore. More than one million people are in relief camps that would take around Rs 300 crore a month to maintain. More than 12,000 kilometres of roads have been damaged hindering speedy relief and rebuilding operation. In totality, the state’s growth rate would be down by one per cent.

The current flood came after a strange phase of the monsoon that defied normal rainfall pattern. On an average, Kerala receives close to 3,000 mm of rains annually. Of this, the monsoon is respo nsible for slightly over 2,000 mm. But this year it surpassed this despite the fact that around a third of the monsoon season is yet to come—by August 19 the state had received close to 2,350 mm of rains. According to IMD, Kerala received 2,346.6 mm of rainfall against a normal of 1,649.5 mm since the beginning of June—an excess of 42 per cent.

Typically, Kerala receives strong monsoon showers in June and July as the southwest monsoon gains strength, after which there is a lull in the latter two months of the monsoon. While the first two months saw slightly above normal rains this year, the normalcy did not extend into August. Within the first three weeks of the month, the state received close to 500 mm of rain over and above the normal rainfall of about 290 mm. Of the 760 mm rainfall received by the state since the beginning of the month, close to 75 per cent was received in the eight days between August 9 and 17, representing a departure from normal by around 300 per cent for the time period.

The distribution of the Indian monsoon is directed by the location of the monsoon trough—a belt of low pressure caused by solar heating. The axis of this trough oscillates between the Himalayan foothills and central India. In its normal position, the trough extends from northwest India to the east coast, close to Odisha and West Bengal. At this position, central India and the west coast get good rains. When the trough moves north the monsoon is said to be in “break” phase and most of the subcontinent barring the Himalayan states receive little or no rain. The “active” phase of the monsoon is when the trough moves south of its normal position causing heavy and intense showers in the southern peninsula. Between August 8 and August 16, Kerala received two spells of widespread intense rains. The first spell of heavy rains prior to August 10 was heralded by just such a system and was anticipated by monsoon trackers.

Atypical cycle

What came as a surprise though was the second spell of rainfall after August 14. The western end of the trough at the time was not stable and oscillated north-south of its normal position. The position of the monsoon trough helped the formation of an offshore trough that is responsible for most monsoon rains in the west coast. However, the instability of the monsoon trough resulted in only a feeble offshore trough. This atypical second spell of rains from August 13 onwards overwhelmed the state by pounding the region with the highest concentration of reservoirs in the state.

Between August 8 and August 15, each of the 14 districts of the state recorded much more than normal rainfall. The worst hit were the districts of Idukki (679 mm), Wayanad (536.8 mm), Mallapuram (447.7mm), Kozhikode (375.4 mm) and Palakkad (350 mm), each of which received rains that were several times more than the normal. The situation further worsened in Palakkad and Kozhikode as heavy rains were recorded until August 18.

“This year the association of monsoon rains with trough position is not as strong as it is in most years. For one, the active-break cycle is not as stark as it is usually and we are seeing more and more extreme events even during the supposed break phase. While this is not unheard of, it is not the typical condition during monsoons,” says Pai. “The feeble offshore trough, off the western coast, is the reason for the high cumulative quantity of rain received by Kerala. While the offshore trough stretching from northern Kerala towards the rest of the west coast is not unusual, the recent rains in Kerala indicate that the offshore trough did not move. The strong monsoon winds converged over a single region and that is why the cumulative rainfall in Kerala has been so high,” says Akshay Deoras, an independent forecaster.

While the offshore trough is the reason for the rainfall, it is not the only determining factor in the distribution of rains. How monsoon winds move and bring rainfall is also heavily dependent on the formation of low pressure systems and depressions over the Bay of Bengal (BoB) and their movement over the mainland. Typically, low pressure systems develop over northern BoB, near the West Bengal coast, and move west-northwestwards. However, during the spate of rainfall in Kerala in mid-August, the low pressure system associated with the heavy rainfall formed closer to the Odisha coast. Subsequently, it moved west-southwestwards towards Maharashtra rather than the normal route that results in rains in central India and the Indo-Gangetic plains. “Generally the depressions associated with such floods occur over the north of BoB. But this time, it occurred over the south of BoB. Initial analysis shows that this might have anchored the monsoon westerlies over Kerala. Normally with the depression over the north BoB, the westerlies would have been towards the north of Western Ghats, with places like Mumbai receiving heavy rains,” says Roxy Mathew Koll, a scientist with the Indian Institute of Tropical Meteorology, Pune.

The numbers of low pressure systems that have developed into depressions that influence the distribution of monsoon rains are below average this season. The climatologically average indicates the development of six well-marked depressions during the four monsoon months—one each in June and September and two in the months of July and August.

However this year, the first depression was formed only in the end of July. With only a little more than a month left, only three depressions have formed so far in BoB and moved into the Indian mainland.

The reduced number of depressions has suppressed distribution of rainfall in the subcontinent and has contributed to the concentration of rainfall over four prolonged spells primarily in the west coast since the onset of the monsoon.

Meanwhile, rainfall in the rest of the country so far does not inspire confidence with only a fourth of the conventional monsoon remaining. Despite floods in nine states, 41 per cent of India’s districts are still facing a rainfall deficit (see ‘Excess rains plague India’).

The trigger

What made this “abnormal” climatic episode deadly were the state’s faulty disaster responses—both short- and long-term. Shockingly, the Central Water Commission (CWC), India’s only flood forecasting agency, doesn’t have any flood forecasting system in Kerala. This deprives the people of the state any reliable way for flood preparedness.

Kerala is ecologically sensitive owing to the geography and topography of the region. Practically, the entire state is drainage medium for run-off from the Western Ghats towards the Arabian Sea. As a result, the state has a dense network of rivers linking the hills to the sea. While rain is abundant across the state, statistics over recent monsoons reveal that it is, in fact, the coastal regions, especially in northern Kerala, rather than the Western Ghats that receive the bulk of the rainfall during the monsoons. Because of this, Kerala’s rivers are spared the flooding risks associated with rivers swollen with heavy volumes of run-off. This year though has been extremely wet for the ghats of Kerala and this is precisely what submerged the state. Between August 1 and August 15, Idukki—which is nestled deep in the Western Ghats and holds 17 reservoirs (the most for any district in the state)—received more than 800 mm of rain. Similarly, in Palakkad which has the second highest concentration of reservoirs, the amount of rainfall recorded between August 1 and August 18 was close to 700 mm. In both these places, the rainfall recorded exceeded 200 per cent above normal for the region and floodgates of at least 29 dams in the districts had to be opened adding to the flood fury and landslides in downstream areas. “The infrastructure definitely added to the magnitude of the flood,” says Vishwas Kale, a former head of geography department, University of Pune and a hydrology expert, adding that, “the situation cannot be compared to the 1924 floods because the level of infrastructure then wasn’t the same as today”.

It is clear by this time that while the state was under a heavy spell of rain, the opening of all its dam gates aggravated an already out of control situation. At least 39 dams were full in the range of 85-100 per cent with water by July end. As the August deluge was not expected, the dams were allowed to fill water till the highest level. The rains in August raised safety issues.

So, while the state was already flooded, 35 dams were discharging water, with all their gates opened at the last minute. “The flood damages could have been reduced by 20-40 per cent had the dams and reservoirs released the water slowly in the two week period when the rains had subsided. The state did not have an advanced warning system in place and released water from the dams only once the danger levels (levels at which the dams structures can be damaged) were reached,” says Ashok Keshari of Indian Institute of Technology, New Delhi.

As per the Crisis Management Plan for Dam Failures, prepared by the National Committee on Dam Safety, states are supposed to come out with their Emergency Action Plans (EAPs) for every large dam.

It’s also shocking that CWC had prepared the guidelines for “Development and Implementation of EAPs for Dams” in May 2006 and had circulated it to state governments for action. According to a recent Comptroller and Auditor General report, out of 61 dams in Kerala, none had EAPs or operation and maintenance manuals.

But before the dam water made the state into a sea, the damage to local ecology done over the years had already caused much devastation. Scanning situation reports of the state’s disaster management control room, one pattern clearly emerges: damage to life and property was more in certain areas. These are areas earmarked as ecologically sensitive and have always been cautioned on landslides triggered by rains. In the second and third week of August, mudslides and landslides were reported in 211 places across the state, and this is attributed to increasing stone quarrying activity and large-scale deforestation.

Idukki and Wayanad are considered among the most heavily-forested districts in the state. However, both have seen a decline in their forest cover between 2011 and 2017. The total forest cover in Idukki came down from 3,930 sq km to 3,139 sq km, a decrease of 20.13 per cent. In Wayanad, forests shrunk from 1,775 sq km to 1,580 sq km, a decrease of 11 per cent. This could be the reason these two districts reported the maximum damages due to flash floods and landslides.

By August 22, the state government was still assessing the impacts of the floods. But the meteorological mayhem indicates a new normal fuelled by climate change. This year there has not been a respite from extreme weather events. And it is one of many such episodes playing out across the world now.

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Wake up before it is too late

From the US and Europe to Japan and Africa, extreme climate events have become an everyday reality. Managing them is one of the biggest challenges of our times

Even as flood waters recede in Kerala and the enormity of the task of rebuilding becomes evident, a similar exercise is unfolding nearly 7,000 km away in western Japan. Between June 28 and July 8, a stationary rainy front, in addition to damp air remaining from the recently-dissipated Typhoon Prapiroon, caused extremely heavy rainfall in western Japan, according to the Japan Meteorological Agency. Total precipitation at many places reached up to four times the mean monthly precipitation for July.

The floods claimed over 200 lives and eight million people were asked to evacuate. However, the process of rebuilding was hampered by another climate anomaly—an intense heat wave that has afflicted the region. Southeast Asia too faced the brunt of flooding with Myanmar, Cambodia, Laos and Thailand recording intense rains and flooding over the past two months.

Weather-wise, the situation has been just as alarming across the globe. 2018 is already one of the hottest years ever recorded. And for this there is no dearth of evidence. As a scorching summer in Asia is followed by intense rainfall and heavy flooding, the other side of the Northern Hemisphere, including North America, Europe and northern Africa, have been in the grip of intense and prolonged heat waves. Temperatures have been soaring above the normal range for nearly six months now, breaking records in several places, including some in South America. Before the mercury rose, the Northern Hemisphere winter too was erratic bringing rains to Europe and blizzards to North America. Expectedly, the wildfire season has been quite active in both continents. The Australian summer early this year too saw unprecedented temperatures and wildfires. However, what has taken observers by surprise is that the upper limit of forest fires and wildfires has now breached the Arctic Circle with around 50 wildfires being reported from the Scandinavian region during summer. Sea ice coverage around both poles have shrunk considerably as temperatures several degrees above average have been recorded over the year.

The overarching source linking these separate instances of extreme and unpre dictable weather anomalies has been identified high up in the atmosphere. The jet stream—a ribbon of high velocity winds that circulate around the Earth several kilometres above the surface—has been deviating from its beaten path. The jet stream in recent times has been observed to be undulating in sharp loops towards the poles and the equator, rather than its normal path which is nowhere nearly as convoluted. The reason for the change in the jet stream paths is ostensibly the increase in global temperatures and the reduction in the gradient between polar and equatorial temperatures which influence the direction of the jet streams. The dust storms and intense convective activity across the Indo-Gangetic plains in April and May 2018 is, in part, attributed to this recent contortion in the jet stream path.

Already in the midst

The striking reality of climate change is that its impacts are already visible in every corner of the world. This is not some far-fetched prediction but is already happening all around us. The distribution of extreme weather and climatological events since the beginning of the year is evidence of exactly this—not a single region of the world can claim to be insulated from the climate change disturbances. According to the EM-DAT disaster database based in Belgium, there have been over 100 climate-related disasters until the beginning of August this year in which close to 3,000 people died (see ‘Extreme is the new normal’).

A look at the trend of reported natural disasters over the past four decades paints an even starker picture. The incidence of climate-related disasters since 1980 have more than tripled to over 300 events every year. Both meteorological and hydrological disasters such as storms, extreme precipitation and floods have increased by as much as four times in the 40-year period.

As climate change impacts increase in frequency and intensity, the most worrying thing is that Earth is only about 10^°C warmer than it was in the 1950s, and that it is firmly on a trajectory that will be between 3-40^°C warmer by 2100. A recent paper published in the journal PNAS in August 2018 looked at historical glacial-interglacial cycles the Earth has undergone, and compared it with a theoretical estimation of future climatological cycles through a systems approach if global warming is not contained. The paper suggests that “the Earth System may be approaching a planetary threshold that could lock in a continuing rapid pathway toward much hotter conditions—Hothouse Earth. This pathway would be propelled by strong, intrinsic, biogeophysical feedbacks difficult to influence by human actions, a pathway that could not be reversed, steered, or substantially slowed. Where such a threshold might be uncertain, but it could be only decades ahead at a temperature rise of 2.0^°C above preindustrial, and thus, it could be within the range of the Paris Accord temperature targets”.

The paper’s conclusion is undoubtedly scary, but there isn’t much evidence to counter the inference that the resear- chers have reached. The PNAS paper is a timely publication; in some ways is an apt curtain raiser for the much-awaited Intergovernmental Panel on Climate Change’s (IPCC) 1.5 Degree Special Report. This report may well determine the urgency and efficacy of the post-Paris Agreement climate action.

While the final version of the report will only be published this month, a preliminary draft was leaked earlier this year. Average temperature rise globally has escalated year-on-year, especially since the 1990s and is currently close to 1.20^°C above the pre-industrial average. Around the Arctic Circle, the increase is around 40^°C above pre-industrial levels. The leaked version of the Special Report unsurprisingly suggests that the Earth is on its way to breach the lower limit for warming of 1.50^°C set under the Paris Agreement. The report points out that though limiting warming to 1.50^°C is still geophysically possible, but it would require drastic and rapid reductions in greenhouse gas (GHG) emissions by governments which would include a sharp shift from fossil fuels as well as removal of carbon dioxide (CO₂) from the atmosphere.

According to the draft, humanity can emit just 580 billion tonnes of CO₂ equivalent of GHG to get a better than 50 per cent chance of limiting warming to 1.5 0C. At the current rate of emissions, this is roughly 12-16 years from now. In 2016 alone, 53.4 billion tonnes of CO₂ equivalent GHGs were emitted globally. The draft has warned that adhering to the limit would require a shift towards renewable as the dominant source of energy, coupled with efforts to increase forest cover and other carbon sinks to sequester GHGs. According to the authors, any emission pathway with greater-than-50 per cent chance of limiting warming to under 1.50^°C until the end of the century would require the world to reach net-zero emissions around mid-century.

While the urgency of the situation is clear—both from the science of climate change as well as from mounting climatic experiences across the world—the emission pathways currently underway will hardly change the trajectory of global warming. One can only hope that the next rounds of climate change negotiations will include the urgency of addressing the dawning realities of the Anthropocene.