Inundated roads, precious lives at risk, rail, road and air traffic hit! That’s how inhabitants of the country’s commercial capital welcome monsoon rains, year after year. Mumbai receives an average annual rainfall of 2100 mm, all of it during the monsoon months from June to September, sometimes extended to October. The city’s civic body- Brihanmumbai Municipal Corporation (BMC) authorities blame incessant rains for disrupting the normal life but experts have been reportedly blaming the outdated (British-era) drainage system and the rigorous abuse of wetlands with unbridled constructions as the prime reason for the urban flooding.
The city’s population has been growing gradually, making it the ninth most populous agglomeration across the globe. From a headcount of 11.9 million in 2001, it has reached 12.4 million in 2011 but the city's infrastructure has not kept up pace with the rate of population growth.
But what has been fomenting the flooding in this city? it is the disconnect between the hydrology and the urban planning. A research titled-“Impacts of urbanization on flooding of a coastal urban catchment: a case study of Mumbai City, India” by professor, V. Jothiprakash of the Indian Institute of Technology, Bombay claimed that the analysis from toposheet and remote sensing data revealed that there is a spurt in the built-up area of Mithi River catchment (the largest catchment in Mumbai) by 59.66 % between 1966 and 2009. The data also revealed there have been adverse, human-induced influences on the Mithi river's course and its catchment area.
As the water supply increases in the city, it becomes difficult to provide new drainage facilities and as a result, the local system overloads and suffers severe flooding. The cycle of flooding and severe waterlogging has been constantly happening for years now, the worst was the Mumbai floods of 2005. The research also stated that when high-intensity rainfall (>50 mm/hr) occurs continuously for 2-3 hours coinciding with the occurrence of high tides the flooding becomes worse.
When it rains for long hours and especially when the high tide in is in play on the shores of the Arabian sea off Mumbai, the drains get inundated with rainwater. With the rainwater and refuse choking the drains, the contents then pour out onto the streets, adding to the waterlogging woes.
On Tuesday, Mumbai was lashed with heavy rainfall again causing water-logging in low-lying areas of Sion, Dadar, Mumbai Central, Kurla, Andheri and Sakinaka. Nearly 171mm rainfall was recorded at the India Meteorological Department observatory at Colaba in south Mumbai between 8.30am on Tuesday and 5.30am on Wednesday.
It is high-time that the BMC officials concentrated on four major sectors to solve the prolonged issue of urban flooding. It should include urban planning, stop encroachments of water bodies, assessment of increased weather events and preparedness for the heavy downpour.
The experts of the Centre for Science and Environment (CSE) said that since groundwater was not considered to be critical for water supply, recharge was neglected by urban planners as they valued land, not water. There has to be legal protection for the city lakes, catchment and drainage systems. Urban flooding is also a repercussion of water bodies and their catchment areas which were being constantly encroached upon or were being taken away for housing and other buildings.
CSE analysis shows that especially in South India, the loss of lakes had been widespread. In 1960, Bengaluru had 262 lakes, but today not even 10 lakes are in a healthy state. Hyderabad, too, is losing its water bodies.
A report- Mumbai Marooned: An Enquiry into Mumbai Floods 2005 revealed that one of the major causes of the flooding in the city is due to the destruction of mangroves which severely narrows down the Mithi river. This is also one of the prime reasons for the flooding in Kurla-Kalina-Saki Naka areas. Similarly, Oshiwara too is marshy, mangrove land. Reportedly, the Mumbai Metropolitan Region has been ignored its own warning by developing large commercial centres without paying heed to the need to maintain natural drainage, open spaces and absorption areas.
However, now the BMC and state government need to pay heed to the recurring issue of the urban flooding. The above-mentioned enquiry also stated that there should be better coordination between the Railways and the BMC prior to the monsoon, to clear the areas adjoining the tracks for better drainage of rainwater as well as post downpour activities to drain floodwaters. It added the 70-year-old stormwater drainage system which was designed to take not more than 25 mm of rain during high tide needs to be replaced, otherwise, all the other drains discharge of wastewater starts overflowing whenever rain in excess of 25mm per hour.
The views expressed by the author are personal and do not in any way represent those of Times Network.