Will Kochi be the same in another hundred years? The short answer is no.
Thanks to climate change, the Kochi-Vembanadu belt may become less hospitable in another hundred years. Rising sea levels, extreme rainfall events and intense tidal flooding can have undesirable consequences for this economically and strategically important and ecologically sensitive region.
As a consequence of the accelerated warming of oceans and thawing of arctic glaciers, sea level has been rising at an increasing rate worldwide. The reports by Intergovernmental Panel on Climate Change [IPCC] indicate that the port city of Kochi will see a significant rise in sea level in the coming decades, submerging large swathes of low lying areas. IPCC predicts that tidal flooding will become particularly severe in the tropics. Such a phenomenon may be already unfolding in the Kochi-Vembanadu region, aggravated by changes in the rainfall pattern.
Tidal flooding in Kochi
The highest tide occurring in this region, known as Vrischika Veliyettam, sets in during the first half of December every year. During December, the tidal flooding was extensive and prolonged in the region and climate change appears to have had a subtle but decisive role in this.
Recent years have seen an increasing share of the annual rainfall, with heavy rain arriving towards the fag end of the monsoon season. Thus, recent major floods/landslides happened during August-October, which historically used to be a lean rainy season in Kerala. Central Kerala received heavy rains in November and early December. For instance, Kottayam, situated on the eastern edge of Vembanadu, received 4,044 mm rainfall last year. Of which 555 mm or 13.7% in November and December. Normally, these two months get only 217 mm or 7.8% of the total annual rainfall. Compared to the long-term average, Kottayam received 44% more rainfall last year and November and December saw a whopping 156% increase compared to the long-term average for the two months.
Since the lake had abundant water following the heavy rain, the ‘Vrichika Veliyettam’ was particularly bad in the belt last year. Rising sea levels also could have contributed to this. Seawater even reached into the low lying interiors flooding homes and streets. It took several days for the tidal water to recede.
Vembanadu Wetland Ecosystem
Six major rivers originating from the Western Ghats empty into this Ramsar site. It plays a crucial role in regulating water flow from the hills and plains into the Arabian sea and helps control floods in the region. The rising sea level in Kochi can slow water discharge into the lake, thereby aggravating the flooding of the rivers. Due to incessant rains and landslides in Koottikkal, in October, there were unprecedented floods in towns like Mundakkayam and Kanjirappally.
Closing the shutters of Thanneermukkam bund in summer (to save rice fields of Kuttanadu from seawater inundation) and opening them in the rainy season (to avoid floods in Kuttanadu) have the unintended consequence of intensifying tidal flooding in the Kochi-Vembandau belt. Taking cognisance of the recent weather-related disasters and predictions of IPCC, it is likely that the worst is yet to come. The unique physiography and demography of the region will make things even more difficult.
The complex nexus between increasing frequency of rainfall, fluvial floods, rising sea levels, and likely reduction in the effective volume of Vembanadu lake and how this will influence tidal flooding in Kochi in future are poorly understood. This knowledge is needed to evolve sustainable mitigation strategies that go beyond opening relief camps and distributing free provisions when disasters strike.
The rivers are now drying up fast. Water levels in wells and ponds are declining as day temperatures are shooting up, promising Keralites another severe summer ahead. It is ironic that as a result of the pernicious effects of climate change, people of God’s own country have to live in perpetual fear, come rain or shine.
The author is a former director of the Rubber Research Institute of India and Chairman of the International Rubber Research and Development Board in Kuala Lumpur.