July 7, 12:34

Causes of Mumbai Flooding: An Analysis of Drainage System, Urbanization, and Climate Issues

Mumbai, situated on the coast of the Arabian Sea, regularly suffers from flooding during heavy rains despite its proximity to the sea. During such events, streets turn into rivers, transport halts, and areas become submerged, paralyzing daily life. This raises the question of why water cannot drain into the sea and who is responsible: the Brihanmumbai Municipal Corporation (BMC) or the outdated drainage system.

Geographical and Structural Features

The city is surrounded by the sea on all sides, with the Arabian Sea forming its western boundary. Under normal conditions, rainwater should flow into the sea. However, during intense rainfall, water accumulates on streets, in settlements, and in low-lying areas.

The main reason is the city's low geological structure. A significant part of Mumbai is built at a very low elevation relative to sea level, with some areas even below sea level. This deprives the water of a natural gradient for runoff.

Infrastructure and Development Problems

Mumbai's drainage system dates back to the British period, having been created in the 19th and 20th centuries. Today, it is completely inadequate for modern needs. When the city's population was around 10-15 million, it now exceeds 20 million. Population growth, uncontrolled construction, and the presence of slums put immense pressure on the existing drainage system.

Drainage channels are not cleaned in a timely manner, accumulating garbage, plastic, and waste. During the rainy season, these channels become clogged, and instead of draining, the water begins to overflow. Furthermore, in many places, the drainage pipes are too small to handle the volume of water during a heavy downpour.

Role of the Municipality and External Factors

The BMC is the largest municipality and bears primary responsibility for the drainage system, road maintenance, and flood management. For many years, the BMC has been accused of failing to clean the channels before the monsoon season, and pumping stations are malfunctioning, with many old pumps being in poor condition.

Nevertheless, the BMC states that it is undertaking large-scale works, including expanding intermediate canals and modernizing pumping stations. Experts note that the pace of work is extremely slow, costs are rising, and accusations of corruption and contractor collusion periodically arise.

In recent decades, chaotic construction has taken place in Mumbai: mangrove forests have been cleared, hills cut down, and low-lying areas filled in for building construction. This has led to the closure of natural drainage paths and reduced the soil's ability to absorb moisture.

Unauthorized constructions in slums and residential areas block drainage lines, leading to water stagnation and flooding. Climate change has become another major cause of flooding in Mumbai. Global warming is raising the temperature of the Arabian Sea, causing more intense precipitation over shorter periods.

Climate Impact and Need for Measures

Sea-level rise also increases the risk of flooding in low-lying cities like Mumbai. The simultaneous occurrence of high tide and heavy rain hinders water drainage because the high sea level causes a backflow in the drainage system. Ocean temperature cycles, such as El Niño and La Niña, affect the monsoon, making it irregular, although experts emphasize that El Niño is not a direct cause of flooding.

Moreover, the daily generation of thousands of tons of waste in Mumbai, much of which is dumped into the canals, exacerbates the problem, as mangrove forests and natural flood defense systems are destroyed. Many bridges, canals, and pipelines are outdated and cannot withstand the current load.

Experts insist on the need for a comprehensive plan for Mumbai, which must include complete modernization of the drainage system, preservation and expansion of mangrove forests, stricter control over unauthorized construction, mandatory implementation of rainwater harvesting, and the use of smart city technologies.

Thus, the flooding problem in Mumbai is the result of a combination of factors: an outdated drainage system, BMC shortcomings, unplanned development, climate change, and weather irregularity. The city's low elevation, blocked canals, and rising sea levels make water drainage difficult. Urgent joint action is required from the BMC, the Maharashtra government, and the central government to make Mumbai globally flood-resilient.

www.aajtak.inJuly 2, 07:51

Delhi's water supply system faces problems: from summer water shortages to rainwater runoff into sewage

With the start of July, the first monsoon rains began in Delhi, following a period when residents in many areas experienced severe water scarcity. In May and June, with temperatures reaching 45–48 degrees Celsius, people were seen queuing at government and private tankers with buckets and pipes.

The problem of rainwater runoff

However, the situation has drastically changed: millions of liters of clean, fresh rainwater are flowing through dirty drainage ditches into the Yamuna River and leaving the city. This annual phenomenon is not a natural wonder or a disaster, but rather a reflection of serious systemic failures caused by government negligence, bureaucracy, and municipal authorities. Since this problem has existed for decades, an effective rainwater harvesting system has not been established.

Potential and reality of water collection

The total area of Delhi is about 1,486 square kilometers, and it receives an average of 611 millimeters of rainfall annually. If all this volume of water were directed into the ground or conserved, Delhi could save approximately 907 billion liters per year. This reserve would be enough for the needs of the entire population of Delhi for about 270 days. Although complete conservation of all precipitation is impossible, achieving a level of 40–50 percent would significantly benefit the city's residents.

Nevertheless, in practice, less than 5 percent of all this water penetrates the soil. More than 95 percent flows along the streets into drainage systems, causing flooding situations.

Contrast between demand and supply

During the summer period, the water demand in Delhi reached 1,200 million gallons daily from March to June. However, the Delhi Jal Board could only provide about 930–950 million gallons per day, resulting in a deficit of approximately 250 million gallons daily.

Another indicator shows that if 100 millimeters of good rain falls in one day and all this water is conserved, this volume would be enough to fully supply Delhi for 14 days.

Main causes of the problem

There are three main reasons for this problem. Firstly, there is disregard for regulations. Delhi has a requirement that all new buildings or structures over 100 square meters must have a rainwater harvesting system. However, out of approximately 17–18 million buildings, only 1–2 percent have this system operational. Most often, obtaining a certificate requires showing a hole on paper, which is then filled with earth and used for parking, without a reliable verification mechanism.

Secondly, state-owned installations do not function properly. Water collection systems installed in government schools, flyovers, and metro stations are in poor condition. These systems should be cleaned before the rains, but, as in this year, more than 60 percent of locations did not undergo such cleaning. As a result, upon the first rain, the soil clogged these reservoirs, and the water flowed down the streets instead of penetrating the ground.

www.aajtak.inJune 24, 06:34

Heavy rains in Mumbai caused flooding of approaches, streets, and railway tracks

The first heavy rains of the monsoon season turned all of Mumbai into a sea, bringing residents both relief from the heat and new problems. Since June 23, when the monsoon began, the situation started to worsen, and the consequences of the heavy rains were observed in the morning. Puddles formed in many places, slowing down traffic, and water accumulated in basements, including Andheri Subway. Due to this, the Brihanmumbai Municipal Corporation (BMC) suspended traffic movement through some approaches for safety reasons. Flooding was also observed on the Western Express Highway, and puddles formed in areas such as Gandhi Market in Sion. Furthermore, the railway tracks at Dadar station were underwater, which seriously affected the operation of local trains, some of which were delayed or canceled. The India Meteorological Department (IMD) issued orange and red warnings for the areas of Mumbai, Thane, Raigad, Palghar, and Sindurdurg, forecasting moderate and heavy rainfall.

Thirdly, there is no single responsible authority for water supply in Delhi. The Delhi Jal Board handles water supply and billing, MCD is responsible for cleaning small drains, PWD oversees the drainage systems of major roads, and DDA owns large city parks and open spaces. When flooding occurs during the rain, each department blames another, and the core issue gets lost.

Conclusions from official reports

According to a report by the country's largest state audit body, the CAG, an important conclusion was drawn: 51–53 percent of the water treated in Delhi is lost before reaching consumers due to leaks, theft, and damaged pipelines, whereas the acceptable loss rate should not exceed 15 percent. The CAG also noted that the Delhi Jal Board lacks a clear long-term water supply plan.

The impact of concrete on the problem

Another serious problem in Delhi is the widespread coverage of the city with cement and concrete. When rainwater falls on the soil, about half of it seeps into the ground. But when the same water hits roads covered with cement or tiles, 90 percent of it runs off without stopping. Parks, sidewalks, and streets in Delhi are almost entirely paved with tiles and cement, which prevents water from penetrating the ground.

The Delhi government has initiated several major projects, including the construction of large ponds along Pushpa Road and the Yamuna River to retain rainwater and allow its infiltration into the ground. Furthermore, the restoration of about 250 old ponds, such as Bhalswa and Sanjay, has begun.

However, there is a significant shortcoming: all these works are being carried out on large government territories far from the city, while the main population of Delhi resides in areas like Samghan Vihar, Patel Nagar, Uttam Nagar, and Karol Bagh, where no local-level work is being done. Retaining water only along the banks of the Yamuna will not prevent groundwater rise in Karol Bagh. The problem will not be solved until water is retained in every neighborhood within that same neighborhood.

Proposals for solving the problem

A specialized body must be created that will bear full responsibility for water issues to eliminate mutual accusations between various departments. The inspection of water collection systems in large buildings should be conducted not only based on paper reports but also through manual physical audits, flow meters, and digital water meters.

It is also necessary to establish small retention pits in parks in every neighborhood so that the water remains within its own area and seeps into the ground. Additionally, when constructing new roads and sidewalks, tiles and blocks that promote water infiltration into the ground should be used.

Private tanker trade

A significant portion of Delhi's water supply comes from private tankers, but precise data on this sector is unavailable because the Delhi Jal Board only accounts for its own tankers. Private transporters illegally draw water from wells, the Yamuna, and sometimes from the board's supplies.

There is a dark side to this sector: complaints about theft from board wells, bribes to the police, and the operation of wells without permits are common. People prefer to buy expensive private water instead of waiting for government tankers, which fuels the growth of this business.

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