Floods

A Perennial Menace

Every year, the entire nation laments the havoc wrecked by the floods in one or other parts of the nation. The memories of floods devastating Uttarakhand, Chennai, Assam, Hyderabad, and Kerala are still afresh. Not even a year passes by without the floods leaving behind trails of agony. Floods aren’t new to India. Even the highly advanced Indus Valley Civilization, according to one hypothesis, is believed to have been wiped off due to recurrent floods caused by the Indus River. However, the frequency and the scale of devastation of the recent floods are unprecedented and hence warrant a thorough discussion which we shall do in this article.

What are Floods?

“A flood is an overflow of water that submerges land that is usually dry. It is a state of higher water level along a river channel or on coast leading to inundation of land that is not normally submerged.” So, it implies inundation or submergence of land by water due to several reasons.

Types of Floods in India: Floods in India aren’t homogenous. There are several kinds of floods, each differing in their genesis and impact.

  1. Coastal flood/surge: It usually hits the areas/states that lie on the coast of a sea. It is usually a result of high tides storming the coastal area. Usually, the eastern coast of India is vulnerable to such floods as it is more prone to tropical cyclones. Also, rising sea levels submerge huge swathe of coastal areas.
  2. Fluvial (River flood): It happens when a river overflows its valley due to the continuous addition of water due to incessant rains. Rivers could also swell due to the melting of glaciers upstream. River floods cause huge devastation as they result in the collapse of dams and breaching of river embankments and thus result in huge human and property losses. Rivers like Godavari, Krishna, Ganga, and the Brahmaputra are notorious for this.
  3. Pluvial (Surface flood): It is usually caused by incessant rains that leave a huge pool of water on the surface, independent of the overflowing water bodies. It occurs in urban areas where the scope for seepage of water is dangerously low. This could also result due to the breakage of drains and sewer networks in the cities.
  4. Flash floods: Although this could happen anywhere, they mostly happen in mountainous regions. Flash floods are nothing but a heavy downpour of water over a small area for a short spell. Flash floods caused by cloudbursts have become increasingly common in the mountainous regions of India, especially in the Himalayan belt. We shall discuss in length about its mechanism later in the article.

Vulnerability profile of India

India is highly prone to several floods owing to its varied geography. Out of the total geographical area of 329 million hectares, more than 40 million hectares (about 12%) are prone to floods. As per NDMA, on average every year, floodsAreas Prone to FLOOD affect 75 lakh hectares of land, 1600 lives are lost and the damage amounts to Rs.1805 crores due to floods.

India’s flood-prone zones can be categorised into three regions. First, the northern plains are traversed by rivers like Ganga, Brahmaputra, Kosi, Damodar, etc. States like UP, Bihar, Assam, Uttarakhand, and West Bengal are most affected. Second, the north-western region is traversed by Indus and its tributaries. States like Punjab, Haryana, and Kashmir are most impacted. Third, central and peninsular India, which are traversed by rivers like Narmada, Tapti, Godavari, Krishna, Mahanadi, Tungabhadra, Chambal, Kaveri, etc. Gujarat, Maharashtra, Andhra Pradesh, Tamil Nadu, and Odisha fall under this.

Causes of Floods

Natural Causes:

  1. Heavy precipitation: In India, most of the precipitation (around 70%-80%) occurs during the span of three months (June-august). As a result, a huge inflow of water can be seen over the landscapes and the rivers. Rainfall of about 15cm in a single day would breach the carrying capacity of the river banks, resulting in flooding of proximate regions. This is a common factor in the Western Ghats, Indo-Gangetic plains, Sub-Himalayan west Bengal, Assam, etc. The extreme rainfall events exacerbated by climate change result in a heavy downpour of rain concentrated over small geographical pockets, which ultimately end up causing flash floods.
  2. Cyclones: Cyclones cause floods in dual ways. First, they would storm the seawater onto the coastal lands and inundate them; later, they cause heavy rainfall in the interiors and submerge the landscapes. States like West Bengal, Odisha, Andhra Pradesh, and Maharashtra are more prone to these cyclonic floods.
  3. Rise in river bed: As the river ages, the amount of silt and sediments brought down by it from the upstream also rises. As a result, the river level rises and spills over the embankments into the neighbouring plains.
  4. Silting in Delta areas: The excessive deposition of silt at the deltas by the sea tides lessens the discharging capacity of the city. This causes the river water at the mature stage to flood the nearby areas.
  5. Earthquake and Landslide: It is observed that sometimes earthquakes and landslides would change the course of rivers. Such instances were found to have caused floods in Jammu &Kashmir, Himachal, Uttarakhand, etc.

Anthropogenic causes

  1. Encroachments of river beds and water bodies: The number of wetlands is drastically down to 123 in 2018 from 644 in 1956. Similarly, Chennai, which was once plush with numerous lakes, was today down to having only a few handfuls of lakes. During the 1890s, Chennai was blessed with 60 major water bodies in the core of the city; however, now it is down to 28. The same is the case with Hyderabad. Encroachments on natural water bodies would deny the rainwater and river water the avenues to flow. As a result, they stray into the cultural landscapes inundating them
  2. Concrete jungles: Indiscriminate expansion of urban areas has turned the natural landscapes into mere concrete jungles. As a result of excessive concretisation, we are closing down the ways for the excess water to seep down into the water tables. As a result, merely an hour of rain is turning our metros into a pool of water.
  3. Blockage of drains: Due to mismanagement of municipal waste and reckless littering, our drains remain choked for the most part of the year. The lack of timely de-clogging measures by the municipal authorities further compounds the woes. As a result, excess water remains stagnant with no scope to drain off.
  4. Deforestation: As we are expanding human settlements at the expense of forests and natural vegetation, we are decimating the natural mechanism to stem the speed of flow of flood waters. As a result, we often see even pucca houses being demolished by the raging flood waters.
  5. Collapse of Dams: India is one of the highly dammed countries in the world. Dams are built to store the water. But, due to poor maintenance, dams have been collapsing due to their inability to withstand the flood waters and are submerging the downstream areas. The recent collapse of the Annamacharya dam during the Tirupati floods bears testimony to this.
  6. Climate Change: The anthropogenic activities like overconsumption of fossil fuels, industrial discharges, etc., have exacerbated the emission of greenhouse gases which ultimately culminated in global warming. Global warming has led to climatic extremities, which manifests in extreme rainfall events, as was being evident in recent years.

So far, we’ve seen conventional floods. But the increasing occurrence of Flash floods caused due to cloudbursts in the recent past necessitates us to have a thorough understanding of it. Cloudbursts have become a common phenomenon in India, particularly in the Himalayan belt, wreaking havoc on lives and properties. Though flash floods due to cloudbursts are similar to conventional floods in terms of impact, their genesis varies from that of conventional ones. Hence, we shall discuss it in isolation.

Flash Floods and its Mechanism

There are many reasons behind flash floods, like cloudbursts, melting of glaciers, collapsing of glacial barriers, etc. But our main point of discussion is flash floods that are caused by cloud bursts as India has been increasingly witnessing cloud burst triggered disasters in recent years. As recently as on July 8th, a cloud burst triggered flash floods have killed 16 people en route to the Amarnath yatra in Jammu and Kashmir.

Cloud bursts, as we have discussed earlier, are highly localized events wherein a sudden outburst of heavy rain for a short duration inundates the area. The India Meteorological Department (IMD) defines it as “Unexpected precipitation exceeding 100mm (or 10 cm) per hour over a geographical region of approximately 20 to 30 square km”.

Why do cloudbursts occur in hilly areas?

Though cloudbursts are confined to hilly areas, they usually happen in hilly areas most of the time. In hilly areas, there exists a warm air current that ascends the slope of hills. When a cloud that is already saturated and ready to downpour arrives, instead of precipitation, it is further drawn up by the air current. In this process, it draws more water from the atmosphere, and as a result, the droplets grow in size. Such clouds are called Cumulonimbus and may attain a height of 13-14 km. After a certain point, the drops become too heavy to hold on anymore and hence drop-down collectively in a quick flash.

Cloudbursts grabbed the headlines for the first time in August 2010, when they resulted in floods that devastated Ladakh, killing 250 and displacing 9000 people. The worst tragedy struck in 2013 when a cloudburst triggered floods that killed around 6000 people in Uttarakhand. Later in 2016 in Kargil and this year in Amarnath, cloud bursts have been increasingly becoming a recurrent phenomenon in the sub-continent.

Why are flash floods increasing in recent times?

Cloudbursts aren’t something that has taken birth recently. They must have been there since antiquity. But their frequency is what keeps everyone on tenterhooks. The scale of the agony that they leave behind is unprecedented and worrisome. One of the prime reasons touted to be catalysing their increasing frequency is the ‘global warming’.

  • According to the Intergovernmental Panel on Climate Change (IPCC),the Himalayan glaciers are melting at unprecedented rates and are outpacing every other glacier of the world.
  • When these glaciers melt, they form into lakes which are naturally dammed by glacial sediment or other mountainous debris.
  • As the temperatures rise in the Himalayas, the melting glaciers add up to the previously existing glacial lakes.
  • When these already pressurised, glacial lakes are further burdened by the rapid addition of huge amount of rainwater from the cloud bursts, the natural dams would collapse, and the lakes burst out.
  • As a result, water flows down the valleys ferociously, causing unprepared catastrophes.
  • Also, as temperature soars up, the moisture carrying capacity of the air inflates, and this heavy amount of moisture converts into short but heavy spells of precipitation.

Why are they difficult to forecast?

Cloudbursts are highly unpredictable and stealthy weather phenomena. They strike the landscapes without knocking the doorbells. What makes it so difficult to predict them?

– Lack of adequate technological resources like doppler radars and weather stations across the country, particularly in the Himalayan belt. We only have seven doppler radars across the stretch of the Himalayas.

– Difficulty in reaching out to the length and breadth of the Himalayas as the higher reaches are highly inaccessible.

– The duration of the events is so small that it becomes very difficult to study their mechanism thoroughly.

Case study: Uttarakhand flash floods are a classic case of the devastation by a cloudburst. The state has receivedPic 2 rainfall 375% more than the regular average. This unprecedented downpour led to the melting of the Chorabari glacier, which culminated in the eruption of the Mandakini River. Mandakini breached its carrying capacity level and exploded. This sudden burst had flooded Kedarnath, Gobind ghat, Rudra Prayag, etc. The state apparatus failed to respond to IMD’s warnings. The public had no clue of what was befalling and were completely caught unaware. Within hours they were trapped in the structures. Villages like Gaurikund and Ram Bada were entirely wiped away in floods, leaving no signs of their existence behind. As per the researchers at the Wadia Institute for Himalayan Geology, the casualty figure reached around 30,00, although the official figure pegs it at around 6000. More than 5000 houses were raged, and many thousands were stranded.

 Impacts of Floods: Multifarious Agony

  • Loss of Lives & Property: The immediate impact of floods is manifested in the form of loss of lives andPic 3 private and public properties. A study by the DTE-CSE Data Centre of the Central Water Commission reckons that between 1952-2018, floods have resulted in the loss of lives of 1,09,412 people, devastation of 258 million hectares of crops, and collapse of 8,11,87,187 houses, and a total economic loss of 4.69 According to the official records, India suffered financial losses of around 95,000 crores due to floods in 2018, which is 2.6 times more than the previous year.
  • Loss of livelihoods: As infrastructure gets damaged and disrupted, economic activities come to a standstill, and as a result of which vast number of households lose their livelihood. This, in turn, diminishes the purchasing power of the people and further slows down the economic growth of the region.
  • Mass exodus: The loss of properties and livelihood cumulatively force people to migrate to other places en masse in search of new livelihoods.
  • Spread of Communicable Diseases: Floods take a heavy toll on public health. The flowing water gives rise to water borne diseases like cholera, typhoid, hepatitis, etc., in flood hit areas. Also, the stagnant pool of water provides a conducive environment for the spread of vector-borne diseases like malaria.
  • Psychosocial effects: The loss of loved ones and personal properties leave a chronic psychological impact on the victims, especially on children. The trauma would take a toll on their mental health for a longer period.Info 1
  • Hindrance to economic growth: According to the DTA-CSE survey, India suffered a total economic loss of 4.69 trillion between 1952-2018. According to the official records, India suffered financial losses of around 95,000 crores due to floods in 2018, which is 2.6 times more than the previous year. This is a huge setback for any government as money that is supposed to be invested in development plans should have to be diverted to rehabilitation plans.
  • Political repercussions: People from flood hit areas may grow intolerant of the incumbent government, and this may lead to chaos and anarchy.

 Governments efforts to deal with Floods

  • Setting up of National Flood management program in 1954, Rashtriya Barh Aayog in 1976, regional task forces in 1996, and the National Commission for Water Resources in 1999.
  • Government has constructed many Dams for controlling the floods like Bhakra Nangal, Hirakud dam, Damodar valley project, Narmada valley project, etc.
  • National water policy (1987/2002/2012): It has explicit provisions to take flood mitigative measures.
  • Has undertaken various watershed management measures such as improving vegetative cover through afforestation, measures to conserve soil, installing structural mechanisms like check dams, detention basins, etc.
  • National Green mission aiming at massive afforestation.
  • NDMA has taken up Flood Risk Mitigation Scheme (FRMS). It includes,
  • Development of Omni-purpose flood shelters
  • Preparation of River Basin specific Flood Early Warning System
  • Digital Elevation Maps for developing Inundation Models to warn the villagers for evacuation in case of flood
  • Financial support to states that undertake above activities
  • Indian Meteorological Department issues timely flood forecasting which helps authorities to intervene in advance.
  • Inter-linking of rivers to cross-compensate the overflow of water in any particular river valley.
  • CWC National Flood Forecasting Network: At present, Flood forecasts are issued by CWC at 175 stations. Annually, about 6000 flood forecasts are issued by CWC during floods at regular intervals.
  • Flood Plain Zoning: Classifying zones or areas basing up on the magnitudes, frequencies and probability levels of occurrence of floods.

However, despite these efforts from the government, Floods have repeatedly been taking a mammoth toll on India every year. Most of the government’s focus is on flood fighting rather than flood mitigation. There are many shortfalls in the execution of the statutes and policies.

Way forward: In this regard, NDMA has announced a slew of guidelines. Some of them are as follows,

  • After a thorough investigation of the hydrological and morphological profile of the flood prone areas, adequate embankments, flood walls, and flood levees have to be erected.
  • De-siltation and channel improvements of river beds periodically.
  • Formulate stringent statutes to forbid encroachments on river valleys and water bodies
  • Contemplating the feasibility of diverting excess water from rivers to new channels, by-passing the major towns and cities.
  • Should undertake watershed betterment measures such as afforestation, construction of check dams, detention basins, etc., in the catchment areas of rivers to prevent soil erosion and minimise sediment runoff.
  • Establish synergy between various agencies involved in flood management.
  • Achieve cooperation of neighbours in obtaining real time data of water flows of cross-border rivers.
  • Training and capacity building of human resources involved in flood management. The devastation of Uttarakhand in 2013 was exacerbated due to the incompetency of the authorities.

Apart from these measures that are prescribed by the NDMA, government should take up the following measures as well.

  • Strengthening the local bodies by induction of domain experts in planning. We could hardly find any domain experts in local bodies.
  • A ban on encroachments on river valleys and relocation of those already inhabiting those areas.
  • Periodic de-siltation and de-clogging of drain channels, more precisely before the onset of monsoons.
  • Redraw the flood profile of India, as the current one was calculated way back in the 1970s by the Rashtriya Barh Aayog when the satellite imagery and mapping were inadequate.
  • Stationing of permanent NDRF force in flood prone areas so that they can swing into action swiftly.
  • Regular maintenance checks of Dams. Let us recollecthow the Tehri Dam of Uttarakhand had absorbed a massive flood wave of the Bhagirathi River, safeguarding the downstream from unimaginable havoc.

Natural events like floods are inevitable. So, trying to stop them is neither practical nor advisable. Hence, our focus should be on insulating human lives and properties from the vagaries of floods and respecting nature. The recurrent floods were the domino effect of human-driven greed and human’s tendency to take nature for granted. This needs a holistic, long-term approach and a collaboration between government agencies, Scientific experts, civil societies, and the citizenry.

References

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