Why monsoon need not be a nightmare in Delhi
For all the romanticism attached to the rain in our ancient texts and contemporary popular culture, our cities fear rapid meltdown every time it pours.columns Updated: Jul 13, 2015 00:44 IST
For all the romanticism attached to the rain in our ancient texts and contemporary popular culture, our cities fear rapid meltdown every time it pours.
All through Delhi’s searing summer, we wait for the monsoon. But when it finally arrives, the idea of even stepping out seems dreadful. Vehicles sink in knee-deep water and roads crumble. Be it Sangam Vihar or Defence Colony, sewage backflow democratically inundates large parts of Delhi. Electrocution from the power poles and dangling wires has already claimed four lives this season.
The backflows are worse in the National Capital Region where expensive gated communities stand marooned with rainwater and sewage hitting the buildings in waves. In the absence of a garbage disposal system, the trash from homes and shops is stuffed into the drains, choking them. So the run-offs mixed with wastewater flows like streams on the roads.
It is the same story every monsoon. When the civic and road agencies get bad press, they respond with those standard “it rained way too much for the city infrastructure to handle” or simply “it was not in our area”. Seasonal monsoon is anyway too brief in Delhi and the agencies simply wait for the headlines to fade out. Who reacts to a story on monsoon preparedness in January, anyway?
However, unlike the monsoon, the reasons for the civic collapse are not seasonal. They point to a sad trajectory of Delhi’s growth and its greed to grab more. At 98%, Delhi has the highest level of urbanisation anywhere in India. This means heavy concretisation and little open space.
Storm water drains and natural channels that used to carry rainwater to the Yamuna have either been converted to mega structures like the Barapullah elevated road and Dilli Haat-INA, or taken over by slums and unauthorised colonies. Elsewhere, residents covered the storm water drains to park their cars or extend their lawns. Most have no qualms dumping construction waste into the channels meant to carry the rainwater.
According to US-based Federal Interagency Stream Restoration Working Group, in a city that has 75-100% permeable surfaces, only 10% of the rainwater goes waste as run-off. While 40% evaporates, which is a natural process, almost 50% gets absorbed by porous soil as precious groundwater.
In non-permeable surfaces such as buildings, pavements and parkings, almost 55% goes waste as run-off and just 15% is absorbed by the ground.
Quoting the study, UTTIPEC, in its plan for storm water management, has suggested the government to treat run-offs from roads locally. Right now, all rain water that falls on Delhi roads goes into the drains and then the nallahs and the river. There is no groundwater recharge. These nallahs also carry sewage. So, the storm water that finally reaches the Yamuna is nothing but a toxic mix.
Instead, the rain water should be soaked up by green patches along the roads and pavements, recharging local aquifers. With 25% of Delhi’s surface being roads, the rainwater harvesting potential is huge, the report concludes.
The New York City, for example, is working on replacing paved roadbed into green spaces filled with trees and shrubs under its Greenstreets programme, which can hold approximately 55,000 gallons of storm water per acre. Most of Chicago’s alleys were originally constructed without any sewer infrastructure. To avoid flooding, the administration started building permeable pavements in 2006 that allows infiltration of up to 80% of the rainfall they receive.
On a much smaller scale, activist Padmavati Dwivedi in south Delhi’s Sarvodaya Enclave is persuading her neighbours to replace concrete tiles on the pavements outside their homes with grass pavers. The cost is the same and it does not require digging up the pavement when some underground pipe needs repair. One can just remove the paver and simply put it back again once the work is done.
The local municipal officers say they are impressed with Dwivedi’s initiative, which should be replicated across Delhi. Overhauls such as replacing the decades-old drainage system will take years to get approvals and funding. Meanwhile, small steps like this may help at least not to dread the next monsoon.