Where has all the water gone?

It was around August 15, 2018, that heavy floods, due to excessive monsoon rain, started engulfing Kerala.

Today, less than two months later, Kerala is facing a very different situation — a searing drought.

The sequence is definitely strange: While alternating intense wet and dry phases are normally taken as two sides of the same global warming coin, here, the time interval is too short — August to September.

“I have not witnessed anything of this kind during my lifetime,” says Saratchandran Nair, a 70-year-old middle-class farmer in Pathanamthitta district, one of the worst affected by the twin calamity of flooding and drought.

Drought conditions after floods have made the earth beneath so parched it is affecting the aquifer; the underground layer of permeable, clay soil where water normally flows.

Sitting in his flood-hit home in Yordanapuram in Thottakam near Kalady, 61-year-old KC Kumaran looks dejected.

Almost one-and-a-half months after the deluge, the senior citizen is staring hard at the reality in front of him. Broken electric cables, a damaged lone toilet in the house and growing cracks on the wall.

Soon after grappling with the flood, he and his family faced a new emergency: the caving in of the earth on one side of his 250 sq ft, roof-tiled, house, and with it, the family’s lone toilet.

For want of a toilet, he and his family rushed back to a relief camp. Only after the intervention of the Kalady Panchayat to build a temporary toilet could he move back to his house.

Sophy Varghese, the Ward Member in the area, describes these developments as “unusual”. There were reports of cracks in paddy fields, and dryness of wells after the floods.

Thanks to some fresh rain, such developments started waning. Quoting experts, she says ‘soil piping’ (a form of internal erosion of the soil that leads to subsidence) might be a reason for the caving in of the earth. (See accompanying story When Nature hits back )

In the case of Elsey Varghese, who stays in Kalady town, the caving in of the well and depletion of water level led to scarcity of drinking water for around 10 days after the floods. The well water was clogged with dirt, and she was forced to depend on tanker lorries until the well was reconstructed with the help of the Panchayat.

Reports of rising mercury levels, unprecedented dip in water levels of rivers, sudden drying up of wells, depletion of groundwater reserves and mass perishing of earth worms, have been noticed in several parts, raising widespread concern.

Major rivers such as Periyar, Bharathapuzha, Pampa and Kabani, which were in spate during the floods, are now quite depleted.

If the severity of the massive floods was second only to the century’s worst recorded in the State way back in 1924, the bone-dry spell that followed was literally draining, emotionally and physically, for the hapless hundreds of thousands of people.

Floods have also altered the topography of the land in many places. Long cracks are visible along the mountainous landscape of Idukki and Wayanad, which witnessed massive landslides. Old streams and rivulets have disappeared, and new ones are seen to be flowing through fields. Wells started emptying out/bottoming out; groundwater receded. The disruption of water flows has befuddled academics and policymakers alike.

D Nandakumar, a Ph D and Consultant on Climate Change and Environment, says he would be cautious about blaming climate change here.

“But you can’t rule it out entirely. Because, even a point one degree Celsius increase in ocean warming could lead to a massive weather change. We have evidence of the Indian Ocean warming abnormally allowing for larger scope for evapotranspiration, cold and warm fronts colliding frequently, and the ITCZ (Inter-Tropical Convergence Zone) shifting base to bring erratic rainfall. The frequency of all this is going to increase. All the reason why we should minimise the micro interventions with our ecosystem,” he says.

The topography factor

According to Thomas Oommen, Associate Professor, Michigan Technological University, the topography of Kerala varies from the coastal plains to the high hills and mountains of the Western Ghats.

Oommen led a team of scientists from the US-based Geotechnical Extreme Events Reconnaissance Association that investigated the impact of the torrential rains across Kerala during a week-long visit sponsored by the US National Science Foundation (NSF).

The floods impact the topography and particularly, they contribute to the possibility of riverbed scouring, explains Oommen.

The latter occurs when the shear stress induced by the flowing water is more than the shear resistance of the channel bed material. The August floods in Kerala resulted in high flows in all the rivers. Such high flows led to excessive riverbed scouring.

The typical riverbed material has low permeability and can hold the water. However, the high flows remove these low permeability materials. In addition, the opening of a number of dams caused high flow in the downstream channels that are also vulnerable to scouring. According to Oommen, the scouring and deepening of riverbeds will lead to lowering of the groundwater table along a river, which can cause a drop in the level of water in wells and dry out vegetation on floodplains.

The lowering of water in the wells and signs of dried up vegetation immediately after the flood do not indicate an impending drought. However, a future drought can be more damaging as the groundwater levels have been already lowered.

According to consultant Nandakumar, the top most portion of the topography of the Western Ghats is occupied by very precipitous slopes which are held together by the vegetation.

“You find shola and grassland ecosystem right on top, mostly shola forests, interspaced with the grassland ecosystem. Immediately below are these slopes, we used to have a good cover of evergreen forests. They are not just evergreen, but also shed leaves throughout the year. So you have a very deep and thick layer of leaves below which lies a layer of loose, heterogeneous superficial deposits covering solid rock. This includes dust, soil, broken rock, and other related materials.

“If this top portion, which is like a sponge, is removed, then land is exposed. Any excess rainfall could lead to sheet erosion here under the combined influence of gravity and the slope. That is what happened in most cases in Kerala.”

Rainfall data for Idukki district shows that it always has had stints with heavy rainfall events but without disasters of such scale, thanks mainly to vegetation cover. But this is simply gone now.

“And you have built dams all over which change the micro-climate entirely. A dam would mean that the forests around the reservoir will be desiccating very fast. This is because winds pick up speed since the water surface acts as an escalator. The moisture also dries up in this manner. There have also been frequent forest fires because of encroachments. In this manner, we set the stage for a major ecological disaster, which is unfolding now. And these will continue unless very strong measures are taken, including a complete ban on quarrying,” warns Nandakumar.

Time for scientific literacy

Girish Gopinath, Senior Scientist, Geomatics Division of the Centre for Water Resources Development and Management, Kozhikode, says the natural calamity in the form of floods and landslides in August has churned the socio-economic fabric of Keralites. It suggests the unscientific urban and rural planning by the policy-makers. Scientific literacy among the community is called for.

He explains that in the last four decades, unscientific urbanisation has changed the geo-morphological (land forms) and natural flood plains of Kerala across the landmass.

There are benefits of flooding despite its immediate ill effects. The development of flood plains with alluvial deposits (sand, silt and clay) is ideal for agricultural purposes.

But such benefits can be experienced only through scientific planning and agricultural activities, he points out.

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