Chennai Rains: Helpless, Hapless, or Hopeless

Mr. S R Ramanan, Former Director of the Cyclone Warning Centre in Chennai; Dr. S Janakarajan, President of the South Asia Consortium for Interdisciplinary Water Resources Studies (SaciWATERs) based in Hyderabad; and Mr. T Kanthimathinathan, an expert on Water Resources, shared their insights on the water scenario in Tamilnad.

Mr. N Sathiya Moorthy

Apart from the rains in Chennai, this time we experienced heavy rainfall in the southern districts, which was unexpected. Tuticorin district, in particular, received very heavy rainfall. It is notable that people in Tuticorin typically do not welcome rains due to their reliance on salt and brick kiln industries, as rainfall can adversely affect their business.

Regarding the recurring issue of floods in Chennai, it is regrettable to observe that even after numerous decades of experiencing heavy rains, floods, and cyclones, we as citizens have not adequately learned our lessons. There is a tendency to shift blame onto whichever government is in power and to lament the lack of essential supplies such as milk, provisions, and electricity during periods of heavy rainfall.

Traditionally, every October first, I would stock essential items in my household, including matches and candles, in preparation for the rainy season. Despite knowing the history of floods in certain regions, individuals continue to purchase land and apartments in flood-prone areas. While it is true that the government sanctions such construction, we cannot solely rely on the government to manage all aspects of rescue and relief operations. In hindsight, it may be acknowledged that the government could have handled the recent flood situation slightly better. However, citizens also bear a social responsibility in such situations.

Mr. S R Ramanan:

Let me begin with the northeast monsoon. For rain or low pressure to form, winds from different hemispheres must merge. From the southern hemisphere, the easterlies cross the equator and become westerly, constituting the southwest monsoon. These winds interact with the easterlies of the northern hemisphere, leading to circulation. A single circle denotes low pressure; two, depression; three, deep depression; and four, cyclone. The convergence of air masses from different hemispheres creates low pressure, marked by the Intertropical Convergence Zone.

North of this zone, winds originate from the east, while south of it, winds come from the west. During the northeast monsoon, low pressure typically forms in the South China Sea, crossing the Malay Peninsula into the Bay of Bengal, intensifying into a cyclonic storm or, sometimes, a low-pressure system affecting our region. However, this year, such occurrences were absent. Despite Cyclone Michaung’s presence, no significant low-pressure systems developed. This made the monsoon season unique. The formation of a trough, another source of rainfall, also did not occur this year, unlike in 2007 when it brought widespread rain to Tamil Nadu.

The Upper Air Circulation

So, how did Tamil Nadu receive rainfall? Initially, air masses from various water bodies—Cape Comorin, Gulf of Mannar, and Bay of Bengal—converged over South Tamil Nadu, bringing significant rainfall. Occasionally, upper air troughs bring rain primarily to coastal areas, but this too was absent this year. Instead, easterly and south easterly winds dominated. An upper air circulation over the southwest bay, as mentioned in the official weather bulletins, contributed to rain along the coast. But the interior districts did not get adequate rains.

The formation of Cyclone Michaung, which approached Chennai, resulted in torrential rains. It did not cross Tamil Nadu but passed near Andhra Pradesh, wreaking havoc there. The upper air, steering atmospheric disturbances, came from the southeasterly direction, a rare occurrence.

Following the mid-tropospheric cyclone, characterized by its upper-level nature at a height of 1.5 kilometers, coastal Tamil Nadu experienced strong winds reaching speeds of up to 20 nautical miles per hour in certain areas, equivalent to 36 kilometers per hour. This led to copious rainfall across Tamil Nadu. Convergence of air masses facilitated the influx of moisture into south coastal Tamil Nadu, extending to the southern interior regions.

Cloud formations reached heights of 14 to 15 kilometers, indicative of the mid-tropospheric cyclone, which remains invisible at the surface. It is noteworthy that while the southeast monsoon is typically observed in states like Gujarat, its occurrence in our region is indeed a rarity. While rainfall was abundant in southern and northernmost districts, many regions experienced normal or below-normal rainfall. North interior Tamil Nadu faced particularly adverse conditions, resulting in agricultural challenges, especially in districts like Krishnagiri and Dharmapuri, heavily reliant on southwest monsoon rainfall.

Weather Prediction Models

Our weather forecasts rely on global models, which are typically more reliable in extra-tropical regions than in tropical areas. While forecasting in the tropics remains challenging, significant advancements have been made. Even in advanced countries like the United States, for tornadoes in tropical areas like Florida, they provide only a 40-minute advance notice, highlighting the difficulty of prediction in such regions.

These models excel in forecasting weather phenomena in the northern part of the United States, where weather systems are influenced by fronts—when cold air meets warm air, creating dynamic weather patterns. Winds predominantly blow unidirectionally from west to east in these regions, making predictions relatively straightforward. However, applying such models to forecast weather movements from, for instance, London to Paris is vastly different from forecasting weather across the entirety of India, particularly in tropical regions.

Despite the challenges, significant advancements have been made in global weather modelling. Institutions like the European Center provide forecasts for the entire world, while America utilizes the Global Forecast System (GFS) model for global predictions. India also leverages the GFS model, which is freely accessible and operational in various centers such as New Delhi and Pune. Additionally, both global and regional models are employed to enhance forecasting accuracy.

Reflecting on past events, in 2006, Bombay experienced significant rainfall, with Santa Cruz recording 93.5 centimeters. It underscores the importance of ensuring unhindered water flow to mitigate flooding risks. States like Kerala and cities like Mumbai have made preparedness for heavy rains. So implementing measures to manage water flow effectively and minimising the impact of inundation or flooding is a very important process of flood mitigation.

Dr S Janakarajan

We’ve witnessed numerous floods over the years, and the intensity of their impact appears to be increasing annually. Take, for example, the 2015 flood, widely regarded as one of the worst in 47 years. The increasing severity of floods prompts many to attribute it to climate change.

A crucial factor contributing to this trend is rapid urbanization. Urban expansion occurs at an alarming rate, often without careful planning. It’s important to recognize the intrinsic link between land and water, as they are closely interconnected. With unchecked urban growth, compounded by rapid industrialization, we’re witnessing the loss of land, agricultural areas, and crucial hydrological pathways.

Need for Integrated Planning

The encroachment upon these hydrological pathways worsens the situation. Areas previously unaffected by floods are now experiencing inundation due to this interference. It’s essential for all of us to acknowledge our collective responsibility in this regard. Addressing these issues requires comprehensive planning and concerted efforts to mitigate the adverse effects of urbanization on hydrological systems.

When water flows uncontrollably, we label it as a flood; however, when it stagnates in an area, we term it inundation. Poor urban planning and a narrow focus solely on development can have catastrophic consequences. Such approaches can result in severe floods and ecological degradation, exerting immense pressure on both present and future economies. It’s crucial to prioritize urban land use planning. Mere enactment of laws isn’t sufficient; stringent enforcement is required.

Despite having our first master plan and nearing completion of the second master plan by 2026, with plans for a third, it’s disheartening to note that we haven’t adequately learned from past experiences. We seem to repeat the same mistakes without applying the lessons gathered from previous plans. This lack of progress affects our ability to effectively address the challenges posed by urbanization and mitigate the risks of future floods and environmental degradation.

Every master plan should include the delineation of ecological hotspots such as streams, floodplains, water bodies, and wetlands—both inland and coastal. Developmental activities must be strictly prohibited in these areas to preserve their ecological integrity. Unfortunately, this crucial aspect has often been overlooked in past plans, leading to adverse consequences. It remains uncertain whether this will be addressed in the upcoming third master plan.

Failure to protect critical ecological zones has resulted in dire outcomes, as witnessed in the Ennore region, where extensive encroachment on coastal wetlands has led to flooding, extending even to north Chennai. The Pallikaranai marshland, which historically spanned 54 square kilometers, has been reduced to a mere 10% of its original size due to encroachment. The marshland serves as a vital flood buffer, but its loss has contributed to the worsening flood situation in the area.

An integrated approach is urgently needed, one that considers land management, water management, flood management, and drought management comprehensively. Efforts must focus on conserving water at its source and protecting both upstream and downstream watersheds. Only through such holistic measures can we effectively address the challenges posed by urbanization and mitigate the impacts of flooding and environmental degradation.

Way Forward

Master Plans must undergo thorough review, with a specific focus on declaring ecological hotspots. Furthermore, these plans should be integrated with drainage master plans to ensure effective water management. Ad-hoc construction of stormwater drains must be strictly prohibited, and layout approvals should only be granted after considering the drainage master plan.

Efforts to conserve water at its source are paramount, as they offer numerous benefits including flood mitigation, enhancing climate resilience, and facilitating the development of climate-smart cities. This can be achieved through initiatives such as tank restoration, desilting, deepening, and increasing capacity.

Implementing Nature-Based Solutions (NBS) within urban areas and the Chennai Metropolitan Area (CMA) is essential. This includes the creation of water detention ponds, constructed wetlands, temple tanks, green parks, urban forests, green roofs, and mangroves. Additionally, there must be a concerted effort to protect natural wetlands, both inland and coastal, ensuring their preservation for future generations.

Mr T Kanthimathinathan

The focus of urban planners often leans heavily towards development without due consideration for water flow management. Many areas in Chennai, such as Mambalam, Nungambakkam, and Nandambakkam, were once lakes. Most errors happened because of flawed land use policy. Many agricultural lands got converted to other uses.  I had personally overseen 20,000 cusecs of water release from Chembarambakkam lake, when I was in office. At that time, there was no flooding, simply because the floodplains were intact.

However, encroachments on floodplains have become increasingly common. Take for example, the Housing Board in Kotturpuram. It is a government construction on the floodplains. Areas like Manapakkam and Nandambakkam were also floodplains. These are expensive areas but when there is flooding, water levels rise up to window lintel levels in these areas.

It is important to implement a master drainage plan before embarking on any urban development initiatives. However, many lands necessary for water flow are owned by private individuals, who have obtained approvals and puttas for development. These floodplains were historically designated as agricultural lands even during British rule, aimed at boosting productivity. Post-independence, importance was given first to green revolution and subsequently to housing drives. However, waterway considerations took a backseat.

Unlike states like Karnataka, Andhra Pradesh, and Kerala, which benefit from the Deccan Plateau terrain conducive to reservoir construction, Tamil Nadu predominantly consists of plains, limiting such opportunities. Hence, our ancestors constructed over 45 minor irrigation tanks, which are now neglected and often filled. The development of areas like Lake View Road, Valluvar Kottam, Nungambakkam, Mogappair, and Padi happened in this manner only.

‘Out of the Boat’ Solutions

As we have neglected waterbodies and other flood prevention measures, now we have to defend ourselves against future floods. For this, it’s crucial to have reliable flood alert and early warning system, along with an effective response mechanism. The government has undertaken various mitigation measures, no doubt. But we can place more emphasis on converting water bodies into navigation canals. When there is a flood, our people find it difficult even to get onto a boat as they are not used to boat travel. If we can, for instance, convert Buckingham Canal into a navigation canal, it could offer cheap and eco-friendly travel from Thiruvanmiyur to Mahabalipuram. When we can construct metro rail systems, we can also look at navigation canals. Implementing water-based transportation systems akin to those in Kerala, could offer viable solutions for daily commute from Velachery to Sholinganallur in boats.