Floods are nothing new in India and are caused by both natural and human-made causes. Even if they cannot be prevented, devastation can be reduced
As of Wednesday, July 17, floods had claimed 67 lives and, according to official figures, affected 46.83 lakh people and 16 districts in Bihar. Thirty of Assam’s 33 districts were under water and a PTI report on Wednesday cited the Assam State Disaster Management Authority (ASDMA), as staring that the death toll in the State had risen to 27. Nearly 90,000 hectares of farmland, much of it with standing crops, have been flooded. Ninety per cent of the Kaziranga National Park, home to the world’s largest population of one-horned rhinos, is under water, as are large parts of the Pobitoro Wildlife Sanctuary and Manas National Park. Other States and their agricultural lands will be affected as the monsoon, which is in its early stages, makes further progress. A red alert has already been sounded in Kerala for extremely heavy rains with the India Meteorological Department (IMD) saying that over 204 mm of rainfall is likely in 24 hours in six districts.
Floods are nothing new and India has experienced far more devastating ones than those this year. The official death toll in the super cyclone that hit Odisha on October 29, 1999, came to 9,885 people. Unofficial sources put the figure at over 50,000. It affected 14 coastal districts, 28 coastal towns and major cities of Bhubaneswar and Cuttack, and around 1.3 core people.
The devastating floods in Uttarakhand in 2013 claimed around 5,000 lives. A report titled, ‘Remembering 2013 Uttarakhand Floods’ (last updated on June 22, 2016) by Soma Basu, Jyotsna Singh, Kumar Sambhav Shrivastava, Ankur Paliwal and Anupam Chakravartty in Down to Earth quoted Rakesh Sharma, Uttarakhand’s Infrastructure Development Commissioner, as saying that as many as 2,052 houses had been wiped out, 147 bridges had collapsed and 1,307 roads destroyed. He further cited preliminary estimates as stating that the disaster had cost the State Rs 50,000 crore in infrastructural loss.
The Odisha flood of 1999 and the Uttarakhand deluge of 2013, among the worst of their kind to hit India, have played havoc. On the night of August 11, 1979, the Machchu-2 dam on Machchu river breached and the flash flood that followed washed away the entire Morbi town causing between 1,800 and 2,500 deaths, according to varying estimates. The floods in Kerala in August 2018 affected all of the State’s 14 districts and caused 445 deaths. In 2017, surging waters devastated the city of Mumbai and the States of Gujarat, West Bengal, Bihar as well as North-eastern India. Floods paralysed Chennai in 2015 and the deluge in Mumbai in 2005 was the worst in the city’s contemporary memory.
While humans are badly hit, animals suffer much more. With almost the whole of the Kaziranga National Park, a UNESCO World Heritage Site, Pobitoro Animal Sanctuary and Manas National Park submerged, flooded animals are moving towards higher ground where they are vulnerable to poaching and road accidents. Not surprisingly, the animal death toll has gone up to 30 with the carcasses of seven, including three one-horned rhinos and an elephant, surfacing from Kaziranga. In fact, animals escaping from Kaziranga are particularly vulnerable because a national highway bifurcates the corridor that links the park to the higher ground. Animals escaping from sanctuaries and national parks are also targets of poachers. With over 150 anti-poaching camps in the Kaziranga National Park affected by the floods, the authorities are working round-the-clock to check poaching at the site.
Floods are caused both by nature and humans. The principal natural cause is heavy rainfall and cyclones accompanied by tidal waves. The latter was the cause of the deluge in Orissa in October 1999. Incessant and heavy rainfall in Nepal have been causing floods in that country and also in Bihar; extremely heavy precipitation in the catchment area of Brahmaputra has been principally responsible for the disastrous floods in Assam. Very heavy rainfall was also the reason for the devastation in Kerala last August, and Mumbai, Gujarat, West Bengal and the North-East in 2017.
Of the man-made causes, the first is global warming, which played, in the form of higher rainfall, a discernible role in the floods in Kerala last year, West Bengal in 2017, and Uttarakhand in 2013. The construction and operation of dams have also been a factor. For one thing, their holding capacity is reduced over the years through silt-deposition by the river water flowing into them. For another, heavy inflow of water caused by incessant rain can cause breaches in dams like Machchu-2, causing flash floods downstream and wiping out towns like Morbi mentioned above.
Things are made worse by the inefficiency that frequently marks the operation of dams. Periodic release of water downstream in optimum volumes is very important to reduce the pressure of inflowing water and increase the strength of the flow and reduce silt deposition downstream rivers. Often, this is not done. Consequently, when the volume and pressure of the accumulated water increases, massive quantities are suddenly released and floods follow. This was a major cause of the Kerala floods last year. Such overspills are increasingly frequent because the holding of water in the dams weakens the currents of the rivers downstream, causing greater silt deposition. The consequent rise in the river beds reduces the volume of water they can carry in their channels and causes overflow of the banks and floods
Other human-made causes include the indiscriminate dumping of debris and muck along river banks, which reduces rivers’ carrying capacities, raises their water levels, thus making it easier for incoming surges of water to overflow their banks. Besides, urbanisation of the watersheds of rivers has altered natural streams and water courses, formed over thousands of years, and led to large-scale encroachments reducing their carrying capacity.
Illegal constructions and thoughtless infrastructure development have severely damaged natural drainage channels in cities like Mumbai, Chennai and Kolkata. The large-scale disappearance of wetlands has also been a factor, particularly in urban areas. Bengaluru, for example, had 262 lakes in the 1960s; now only 10 have any water; Hyderabad has lost 3,245 hectares of wetlands in the last 12 years. Lakes and wetlands, an important part of urban ecosystems, perform significant environmental, social and economic functions, ranging from being a source of drinking water, recharging groundwater to acting as sponges, supporting biodiversity and providing livelihoods.
Clearly, a lot remains to be done. Even if floods cannot be prevented, the devastation they cause can be reduced.
(The writer is Consultant Editor, The Pioneer, and an author)
