What the floods and landslides tell us

3 months, 3 weeks ago 1
Posted in: Blog

Climate change and habitat degradation are the prime reasons, and both point to human activity.

 

Landslides in Munnar, Kerala 2018 ©eos.org

Almost on the dot, exactly a year after the 2018 floods the rains poured down on Kerala causing havoc and claiming lives once again. Some new areas were affected catching residents by surprise, but some of those affected last year were battered again. This time around, lives have been lost mostly to landslides, which steamrolled mud and water on estates and habitations, burying alive over 50 people.

The water levels in most of the dams were not too high warranting an opening up of sluice gates. This has helped avoid the situation seen last year when lives were mostly lost to rising waters submerging homes.

The death toll stands at 104 in Kerala, with 36 people missing and 2.5 lakh living at 1639 relief camps, as per PTI news agency. More than 3000 houses have been damaged completely. On Sunday, Vadakara in Kozhikode district recorded 21 cm of rainfall, the highest in the state, followed by Kodungallur in Thrissur (19.9) and Perinthalmanna in Malappuram (13.8).

In Karnataka too, rains have played havoc and claimed 61 lives, besides seeing the evacuation of nearly 5.81 lakh people and 14 missing. Around 1100 relief camps have been set up so far in 17 districts so far. The worst affected districts are Belagavi, Bagalkote, Vijayapura, Gadag, Uttara Kannada, Raichur, Yadgir, Dakshina Kannada, Udupi, Chikmagalur and Kodagu.

To put it simply, what we are witnessing is a month’s rain falling in a day or two. This results in overflowing rivers and landslides — the extreme weather predicted by many climate change models. Aiding that are the man-made changes to the land. Some of the towns in Kerala that saw streets flooded point to interventions that block the flow of water into the ground, like concretisation. In recent years, this trend has been seen in many traditional homes too where the ground around is tiled or concretised. An area that has seen traditionally heavy rainfall will then get flooded with no way for the water to be absorbed.

So also with the Western Ghats. Once able to hold the rain, today the mountain range has been rendered impotent, thanks to the innumerable ways humans have altered the landscape. Besides being one of the world’s top eight biodiversity hotspots, it serves as a major climate regulator. A scientific study last year showed that evapotranspiration from vegetation in the Western Ghats accounts for one quarter of the rainfall over peninsular India. The vegetation cover acts like a sponge in accumulating moisture and releasing it over southern India during dry periods. In fact, this accounts for up to 50 percent of the rainfall over Tamil Nadu during the minor drought periods in a year. The rains in turn also help bring down the temperature.

Yet another study, this one led by scientists from IISc, clearly showed the link between tree cover and water availability in streams and rivers. Using remote sensing data to see how dwindling forest cover from 1973 to 2016 affected the river Kali in north Karnataka, it showed how perennial streams had water only in areas with more than 70% forest cover. Large reservoirs have come up at the cost of forest cover.

Instead of recognising the ecological significance of the Western Ghats, we have only viewed the economic value and exploited the habitat. The unscientific land use by almost every stakeholder has not only come at the cost of forest cover, but also altered the geology to break point.

 

Many access routes to remote locations have been cut off by the recent landslides. Pic by KFD

Landslides decoded

This time around, following the heavy rains it was the landslides that have taken the maximum toll. According to the Geographical Survey of India, Kerala has witnessed 67 major landslide events and hundreds of minor ones, in half a century. Nadukanichoram in Wayanad which has seen many landslides this time is a place where road construction and widening has been on since two years!

A study undertaken by a researcher from Michigan Technological University after last year’s floods and landslides had already pointed to the reasons for frequent landslides. One of this is a natural one – very heavy rain falling on steep slopes sets the soil loose. The scientists found that in the process of running down, the water ends up forming sub-surface pipes which drained the water making slopes unstable, or the pipes got clogged and ended up creating a huge backlog of water which saw the entire slope finally cave in at some point. However, such naturally occurring landslides made up a small fraction of the 1000 odd landslides witnessed.

A more common reason for the landslides as observed by the team was the man-made structures built on the slopes by cutting them and removing soil. In this process, new ways are created for water to seep underground, eventually leading to a collapse of the slope.

Another contributor to landslides are the water storage units carved out on the slopes by land holders, many of them private entities. These often end up blocking the natural flow of water, and also creating pressure on the steep slopes. Adding to the destabilisation of slopes are also the large numbers of granite quarries operating in some regions. In the vicinity of the recent 11 landslides in Kerala, over 50 quarries are in operation. At Kavalappara in Malappuram that saw a major landslide, there are around 27 quarries within 5 kms around the landslide site, according to a researcher from the Kerala forest research institute.

Tea estates that have replaced grasslands (part of the natural ecosystem that acts as a sponge and absorbs water) on many of the mountains have contributed too in making the slopes fragile, according to experts. It is also pointed that paddy lands, which double up as wetlands and soak in the excess water, are fast disappearing in the state.

The urgent need to regulate land use in some of these sensitive areas was also implied in a Geographical Survey of India undertaking. GSI which has been advocating land use planning and zonal regulations had mapped landslide susceptibility of around 8920 square km area covering Kannur, Kozhikode, Wayanad, Malappuram, Palakkad, Pathanamthitta, Kollam and Thiruvananthapuram districts. The post-disaster landslide assessment carried out by GSI in 2018 after the floods revealed that of the 59 landslide events it recorded in Kozhikode, Idukki, Malappuram, Wayanad, Palakkad and Kannur, 86 percent happened in zones marked as moderate and highly susceptible in the landslide susceptibility mapping.

 

Landslides in Karnataka ©WCS-India

Climate change

Regarding the reason why we are seeing such intense rainfall, climate change studies have been pointing exactly to these kinds of extreme weather events and warning that the world will see more of these as the global climate warms up. The Potsdam Institute for Climate Impact Research recently analysed and quantified changes in record-breaking monthly rainfall events from all over the globe, based on data from roughly 50,000 weather stations worldwide. It was found that generally, land regions in the tropics and sub-tropics have seen more dry records, and the northern mid-to high-latitudes more wet records. This tallies with the patterns expected from human-induced change, according to the institute press release.

The role of Western ghats in regulating the climate is something we cannot afford to overlook. ©Kiran Yadav

Climate change from fossil fuel greenhouse gases has been predicted to disturb rainfall patterns and already we have seen significant increases of such extremes with just one degree of global warming witnessed since the Industrial Revolution. With global efforts falling much short of what is required to limit emissions so that warming can be contained within 2 degrees, such rainfalls and associated landslides, etc will become even more frequent and more intense. Trends indicate we are headed for 3-4 degrees within this century.

Between climate change and man-induced degradation of natural spaces, the scene is set for more repeats of floods and landslides, more often and more intense. On both counts, human action, and inaction, is indicted.

Written by Jayalakshmi K

One Response

  1. Annu Abraham says:

    Informative & Insightful Blog 👍

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