Mohammad Hanief
Excessive or continuous rainfall over a period of days, or during particular seasons, can lead to stagnation of water and cause flooding. Flash floods refer to such a situation, but occurring in a much shorter span of time, and are highly localised.
In India, flash floods are often associated with cloudbursts – sudden, intense rainfall in a short period of time. Himalayan states further face the challenge of overflowing glacial lakes, formed due to the melting of glaciers, and their numbers have been increasing in the last few years.
Frequently, flash floods are accompanied by landslides, which are sudden movements of rock, boulders, earth or debris down a slope. It is common in mountainous terrains, where there are conditions created for it in terms of the soil, rock, geology and slope. Natural causes that trigger landslides include heavy rainfall, earthquakes, snow melting and undercutting of slopes due to flooding. Landslides can also be caused by human activities, such as excavation, cutting of hills and trees, excessive infrastructure development, and overgrazing by cattle.
India is a country that faces the twin challenges of floods and droughts every year. The monsoon season, which brings about 75% of the annual rainfall, is also a time of great variability and uncertainty. Year after year, as the monsoon season progresses, floods wreak havoc, leaving behind a trail of destruction and despair.
As the 2023 monsoon progresses, floods are beginning to repeat the pattern of damage and destruction. The magnitude of this issue becomes apparent when we consider the staggering statistics: an average of at least one major flood event each year, resulting in significant loss of life and extensive damage to land, crops, houses, and public utilities. In the past few years, the occurrence of natural disaster like flash floods has increased in India. This can be attributed to climate change. For instance, the 2018 Kerala floods, 2021 Uttarakhand floods, 2021 Maharashtra floods, 2017 Gujarat flood and many other. A flash flood is often the result of a heavy or excessive rainfall. Whenever it rains, the soil acts as an absorber, and absorbs the precipitation. However, in cases of heavy rain, the soil may be saturated to capacity and unable to absorb any more water.
Flooding can also occur after a drought, when the soil is too dry and hardened to absorb the precipitation. This is why, flash floods are a common scene in desert landscapes after heavy rainfalls. The other reason of flash floods are cloudburst or thunderstorm. It is common in places such as hilly, not too hilly regions and sloping lands. Floods can affect the economic growth and development of India by reducing the agricultural output, disrupting the industrial production, affecting the trade and commerce, and increasing the expenditure on relief and rehabilitation. It can also affect the tourism sector by damaging the cultural heritage and natural attractions. According to a study by the World Bank, floods cost India about $14 billion annually in direct losses.
Floods are among the most common and destructive natural hazards causing extensive damage to infrastructure, public and private services, the environment, the economy and devastation to human settlements. Recurring flood losses have handicapped the economic development of both developed and developing countries. India is a developing country and prone to several natural hazards.
Depression and cyclonic storms in the coastal areas of Orissa, West Bengal, Andhra Pradesh, Karnataka, and Tamil Nadu also cause flash floods. Further, the states of Arunachal Pradesh, Assam, Orissa, Himachal Pradesh, Uttarakhand, the Western Ghats in Maharashtra and Kerala are more vulnerable to flash floods caused by cloud bursts.
In addition to these, sudden release of waters from upstream reservoirs, breaches in landslide dams and embankments on the banks of the rivers can also lead to disastrous floods. The severe floods in Himachal Pradesh in August 2000 and June 2005, and in Arunachal Pradesh in 2000 are a few examples of flash floods caused by breaches in landslide dams.
Floods in Assam, Bihar, Uttar Pradesh, Orissa and Andhra Pradesh are generally caused by breaches in embankments. Incidents of high intensity rainfall over short durations, which cause flash floods even in the area where rains are rare phenomena, are on the rise and the problem needs to be tackled in a scientific manner. According to the ‘Climate change and India: A 4X4 assessment a sectoral and regional analysis for 2030s floods report’, temperature rise in India would increase the frequency of flood events in India during the end of the 21st century (2071-2100). Further, the Himalayan belt is also projected to witness a significant rise in temperature up to 2.6 degrees Celsius. By the 2030s, the intensity is expected to increase by 2-12%.
The report further stated that the temperature rise will result in multiplication of flash flood incidents leading to extensive landslides, which would bring extreme damage to the agricultural area thereby threatening the food security of the country.
Flash floods are dangerous as its occurrences are sudden with less time to respond. It is advisable to listen to weather bulletins to avoid visiting places with chances of a flash flood.
On the authorities front, the NDMA also advices the inhabitation of low-lying areas along the rivers, nullah and drains to be regulated by the state governments/ state disaster management authorities (SDMAs)/ district disaster management authorities (DDMAs) as a preventive measure. Central Water Commission (CWC)/ National Remote Sensing Agency (NRSA)/ state governments/ SDMAs also check for landslides and blockages in rivers with the help of satellite imageries. In case of their occurrence, warning systems are set up to reduce losses. It is also advised to take appropriate structural measures to eliminate the damage in case of sudden collapse of the blockages. Furthermore, the India Meteorological Department (IMD) has been using Doppler radars, a flash floods forecasting and warning systems to predict the occurrence of flash floods. It has been over a week since the heavy rains began wreaking havoc in the Himalayan states, and tragedy continues to haunt northern India, with Jammu & Kashmir now in its scope. Torrential rain over Jammu triggered catastrophic flash floods and landslides, leading to multiple house collapse incidents during last week.
Similar to the dreadful situation in Himachal Pradesh last week, the intense rains swelled many rivers in the region to dangerous levels. This also triggered terrifying flash foods, washing away several important bridges, culverts and roads in their path.
Connective infrastructure suffered heavily at the hands of record-breaking rainfall in the region as well, leading to the closure of many important roads due to flash floods and landslides. This includes the Jammu-Srinagar national highway that connects Kashmir with Jammu, and the Jammu-Pathankot road that connects Jammu & Kashmir to the rest of the country. Hundreds of vehicles were stuck as a result.
According to media reports, devastating floods causing havoc across northern India last week also reached the iconic Taj Mahal in a rare event that experts warn could become a regular occurrence as the climate crisis brings ever more extreme weather.
Floodwaters from the Yamuna River lapped at the compound walls of the monument and major tourist attraction. A garden located behind the Taj Mahal was also seen submerged in floodwater. However, the Archaeological Survey of India (ASI), which maintains the heritage site, said it is not under threat from the current floods.
Experts said it is rare for floodwaters to reach the outer walls of the complex, which was built near the city of Agra in Uttar Pradesh in the 17th century by a Mughal emperor to honor his wife as millions of tourists visit the site each year.
As per the information available on the national disaster management authority website, India is highly vulnerable to floods. Out of the total geographical area of 329 million hectares (mha), more than 40 mha is flood prone. Floods are a recurrent phenomenon, which cause huge loss of lives and damage to livelihood systems, property, infrastructure and public utilities. It is a cause for concern that flood related damages show an increasing trend. The average annual flood damage in the last 10 years period from 1996 to 2005 was Rs. 4745 crore as compared to Rs. 1805 crore, the corresponding average for the previous 53 years. This can be attributed to many reasons including a steep increase in population, rapid urbanization growing developmental and economic activities in flood plains coupled with global warming.
An average every year, 75 lakh hectares of land is affected, 1600 lives are lost and the damage caused to crops, houses and public utilities is Rs.1805 crores due to floods. The maximum number of lives (11,316) was lost in the year 1977. The frequency of major floods is more than once in five years.
(The author is a regular columnist
and can be mailed at [email protected]).
