Monsoon Flooding and Climate Change, is there a link?

Yes, but there's irrefutable human footprint & incompetence written all over it.

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Monsoon once meant fluorescent green landscapes that breathed life into parched earth and our scorched souls. Monsoon today has become a recurring tragedy affecting millions and a mockery of our so-called modern development. Most of you must have seen harrowing videos of flash floods and flooding in Delhi, Gurugram, Mumbai, Jaipur (one more), Dehradun, Andhra Pradesh, Arunachal Pradesh, Karnataka, Kerala (one more), Rajasthan along with the annual Bihar and Assam floods that we have become so inured to that they don’t even register as a major humanitarian disaster despite consistently extracting a heavy toll. Across India this year, 847 people have died while more than 14.8 million have been affected as a result of monsoon-related disasters, as of 18th August 2020[*].

Which makes one wonder, why is all this happening? Is it because the cities are planned badly and have no proper flood management systems in place? Or is it all because of Climate Change? Or is it because of environmental degradation?

The answer is, a bit of everything. From here on, I’m going to take the examples of India & Nepal to illustrate the points further but the same insights can be extrapolated to regions worldwide.

Overall, we can attribute three reasons to this incessant flooding:

1. Climate change causes extreme rainfall of high intensity in short durations.

Some of the most sophisticated forecasts suggest that as the globe warms, more rains will fall in severe, intermittent storms rather than in the kind of gentle soaking showers that can sustain crops. — Read more at Why extreme rains are gaining strength as the climate warms on Nature.

Source: E. M. Fischer & R. Knutti Nature Clim. Change5, 560–564 (2015).

As you can see below, India so far has had a normal monsoon overall but a vast percentage of the country deviated from the expected average precipitation. Seeing the spread of intense blue and red zones across the country in the third illustration, it is clear that many regions either faced deficient rainfall or way too much rainfall (Or you could see this week by week monsoon report from IMD where you can see red and blue dominate the chart). This is scarily, already consistent with what climate scientists at our MoES[*] have predicted for future— that rainfall will be erratic and frequency of extreme precipitation events may increase all over India[*].

Source: India Meteorological Department(*)

A season of extremes:

Mumbai rainfall broke some records this season. In just 65 days, Mumbai received more rainfall than what’s it supposed to receive in over 4 months of monsoon[*]. In the first five days of August, Mumbai received 78 per cent of the month’s average rain.

The Avalanche region in the Nilgiris received 820 mm of rain over a 24-hour period till Thursday morning, the highest in Tamil Nadu’s history[*]. In Kerala’s Idukki, where a deadly landslide claimed 70 lives of tea plantation workers, the Pettimudi station received 1842.7 mm (184 cms) rainfall from August 2-7, the highest rainfall in that period in Idukki district, according to rainfall statistics put out by Pradeep John, a popular weather blogger from Tamil Nadu[*].

Delhi too, has experienced intense and erratic rainfall this year. According to a report in Hindustan Times[*], mere 11 days account for 80% of Delhi’s monsoon rainfall this year and just four days accounted for almost half of the monsoon rain this year in Delhi.

Looking to the past for a glimpse of the future:

Scientists at Climate Research Lab, the Indian Institute of Tropical Meteorology found a threefold rise in widespread extreme rain events over central India since 1950[*], as a response to warming temperatures in the Arabian Sea. These severe weather events result in largescale floods and catastrophic loss for life and property across central and northern India – Gujarat, Maharashtra, Madhya Pradesh, Chhattisgarh, Telangana, Odisha, Jharkhand, Assam and parts of Western Ghats – Goa, north Karnataka and South Kerala.

Extreme rainfall due to global warming is a part of our new reality and there is no point denying the role of climate change in monsoon related disasters plaguing our world. However, it is important to recognise the other factors that also contribute to this recurring, intensifying catastrophe significantly.

2. Unscientific and haphazard infrastructure planning and lack of adequate flood management

When it rains, there are three things that should happen in a normal case - 1) the rainfall seeps into the ground, recharging our groundwater aquifers, 2) rainfall finds a way to a larger waterbody like lakes, wetlands or oceans by flowing over surface, or 3) saturates the soil/land surface which then evaporates back into the atmosphere or is used up by plants.

Urban development interferes with all three processes because either the surface is disastrously covered in concrete hindering seepage of water underground or we block the natural drainage outflow path. Both of these cause urban flooding because the immense amount of water finds no way to escape.

Cities ideally should have adequate, well connected and widespread storm drainage sewers, plenty of green spaces to absorb and buffer the precipitation, and several waterbodies like lakes or ponds where the excess water runoff can be collected. But none of our cities, except Chandigarh perhaps, are designed with a vision. It seems unmitigated and unplanned expansion is our only plan.

To understand all this more, see the informative short film by Urban Design Research Institute that delves into the recurring flooding issues in Mumbai and the the lack of the city's response i.e. flood mitigation measures/ provisions, to address the same, especially in low-lying areas.

Also see the thread below to understand how floodplain encroachment and building over riverbeds leads to flooding, in this case water flowing through a fancy new IT Park in Dehradun recently.

These are just two examples but a similar “development” story can be found across all our cities where inadequate or non-existent flood management & haphazard encroachment of flood prone areas and waterbodies compounds with climate change induced extreme rainfall, often bringing our cities to a grinding halt.

3. Ecosystem destruction and land use change that greatly exacerbates flood risk

There are several features in our natural ecosystem that are excellent at flood mitigation. Forests, wetlands, mangroves, urban trees all are able to help the earth absorb rainfall, prevent erosion and landslides, act as a buffer from storm surges and such. However, in the name of development, the assault on environment continues on unchecked, leaving us grossly vulnerable to climate hazards.

This monsoon in Nepal has been particularly devastating. Over 300 people have lost their lives due to landslides[*] as of today caused by extreme rainfall, the highest toll from landslides yet. However, it is important to note that it wasn’t just rainfall that caused the landslides, it was also bad infrastructure development that weakened the mountain slopes.

Experts say that, apart from the impact of earthquakes, erratic rainfall,  haphazardly  constructed infrastructure — mainly roads — and scientifically unsound farming practices are making the region more vulnerable to landslides. Across the nation, more landslides have occurred in locations with recent road construction projects that have used heavy equipment while neglecting environmental impact assessments, showing an unmistakable correlation. — Read more at The deadly combination of rains, roads, and landslides on Record Nepal.

In Karnataka’s Kodagu that has seen devastating landslides over the last three consecutive years, experts aren’t convinced only rainfall is the cause of destruction.

While experts admit that there have been noticeable changes in the rainfall pattern in the district in the last few years, they are reluctant to attribute the annual flooding completely to climate change. Experts also blame the modification of land use to accommodate tourism and linear corridors. — Read more at Heavy rain is not the only cause of the floods and landslides in Karnataka’s Kodagu district | Scroll.

Incidentally, recognising the need to restore ecosystems to adapt to climate change, Nepal was awarded its first ever Green Climate Funding of $39.3 million[*] last year for building resilience of Chure region, where rampant environmental degradation and unchecked exploitation of Chure Hills for natural resources is causing severe flooding issues for downstream communities in the low-lying plains of Terai. [*]

It has to be noted that while Nepal received 30% of excess monsoon rainfall above the normal average overall this monsoon, Karnataka’s Kodagu received 116 mm of rainfall which is a 454% departure from normal in the 24 hours ending at 8:30 am on August 6 2020, during which time the landslip occurred. It is only reasonable to conclude that heavy rainfall when combined with vulnerable and weakened natural habitats, leads to greater environmental disasters and higher casualties.

So what’s the solution to deal with recurring floods and extreme rainfall?

Broadly speaking, these are the four things we need to focus on if we are to minimise impacts of floods in future.

  1. Integrate climate risk in all further development and correct existing infrastructure to build resilience and deal with flooding events which are inevitable in our imminent future.

  2. Invest in community preparedness and robust flood warning systems so people can escape the worst of flooding and landslides at the very least without being caught off guard.

  3. Ecosystem restoration, where nature is able to heal itself and inflict less damage on us, is an important aspect of building resilience to minimise the impact of future risks.

  4. Most importantly, REDUCE GREENHOUSE GAS EMISSIONS AND REACH NET ZERO AS SOON AS POSSIBLE!

This is a very generic, broad level introduction to climate change and flooding but I hope this gives you a good idea of how to view these interconnected issues of global warming, environmental degradation and development. We definitely have to be careful not to cover up our incompetencies and inadequacies as climate change impacts but fact remains that climate change will worsen almost every existing flaw of our society and civilisation, which is why, I’ve been harping on over the last three posts that Climate Action = Mitigation + Adaptation and we need it right now.


Three related articles you should read:

Floods in India are turning more severe, unpredictable and rather intractable. In 2018 alone, India suffered damages worth over Rs. 950 billion due to floods. Number of urban floods is on the rise mainly due to poor drainage and encroachment of old water bodies of cities and towns.

Read more at: Floods across the country highlight need for a robust flood management structure | Mongabay

Due to global warming, the trend of extreme monsoons with long dry spells alternating with very heavy rains is here to stay. This uneven distribution of rainfall is one of the reasons for floods and landslides, apart from the damage to agriculture.

Read more at: India's Uneven Monsoon Rainfall | Mint

Preliminary findings of an ongoing research by WRI-India indicate that 35% (428 sq.km) of new development within 20 km of the city centre (2000-15) in the nation’s 10 top cities — Ahmedabad, Bengaluru, Chennai, Delhi, Hyderabad, Jaipur, Kolkata, Mumbai, Pune, Surat — has been on low-lying and high recharge potential zones. Unsurprisingly, these cities have seen multiple flood events in the last five years.

Read more at: Unless India invests in green infra, the future of cities is dark and grey | Hindustan Times


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