Floods are natural disasters, but their intensity and frequency have increased over the years. The current monsoon season is an apt reminder of what climate change would do to our rivers if global warming continues unchecked.
Despite its late onset, the southwest monsoon covered the country six days in advance. In the days to follow, it unleashed its fury over the Himalayan states, triggering one of the most devastating floods over Northwest India which also recorded its wettest July in 22 years.
The unforeseen July floods pounded the states of Punjab and Haryana, just when the farmers were preparing to sow Kharif crops. Haryana declared floods with over 1,300 villages inundated. The Himalayan rivers surged crossing their danger mark, as floodwaters over-topped the banks. In Delhi, Yamuna breached its all-time high mark — first time in almost 45 years. The national capital recorded its highest-ever 24 hour rainfall in July in over 41 years. In the east, Arunachal Pradesh, Assam, and Sikkim bore the brunt and now Gujarat has been battered by heavy rains and multiple reservoirs are overflowing, causing massive damage.
INCREASING WEATHER EXTREMES
From one of the wettest July to driest August in almost 100 years, the southwest monsoon — lifeline of India’s agri-based economy — is now more erratic than ever. These intra-seasonal variations are bound to get more extreme in a warming world, climate scientists warn. India recorded its hottest August since 1901 with the highest average maximum temperature of 32.19ºC.
Warm atmosphere can hold more water and for longer duration. Scientific analysis shows the air can generally hold around 7 per cent more moisture for every 1-degree Celsius temperature rise. This means any ordinary rainfall event can have a higher probability of intensifying into an extreme or exceptional rainfall event with over 200-250mm rain.
Rainfall patterns are changing with torrential downpours in a short period of time. A characteristic feature of winters, the western disturbances are now more active during the monsoon season. What we saw in Himachal in July was a result of a strong interaction between this system and a vigorous monsoon. Timely weather forecasts are crucial, but experts warn that instead of waiting for weather forecasts yearly, we need to re-assess the flood risks locally and prepare.
WHY NO FLOOD PLAIN ZONING?
Floods are natural events but they turned into massive disasters when humans encroached on the flood plains. So, when the river swells, it is bound to submerge everything that will restrict its flow.
“The intensity of rain is bound to go up. Those once-in-a-50 years or once-in-a-100 years’ floods will become more frequent. That’s exactly what we are witnessing now. There has been rampant encroachment of the floodplains, and when these rivers swell, they will destroy everything that may restrict their flow. Despite all the warnings, flood plain zoning is not being done in our country,” says Professor Emeritus AK Gosain at Department of Civil Engineering, IIT Delhi.
Years after the Centre circulated a Flood Plain Zoning legislation, many of the flood-hit states are yet to delineate and demarcate their flood plains. The policy requires a clear identification of these regions on both sides of the river which are likely to be affected by floods of different magnitude or frequencies and probability levels.
It also requires states to specify and regulate the activities that are permissible in these zones, so that whenever floods actually occur, the damage can be minimised. While Manipur, Rajasthan, Uttarakhand and Jammu and Kashmir have enacted the legislation, this crucial measure to mitigate floods is yet to be undertaken.
“The increasing torrential rainfall, deforestation, and unchecked construction have increased the magnitude of the disasters. As humans, we have been challenging these mountains’ capacity for many years now. Increasing anthropogenic stress will only lead to disaster,” says Professor YP Sundriyal, Head, Department of Geology, HNB Garhwal University, Uttarakhand.
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