Delhi’s roads are flooded every monsoon — because the real rivers that once drained the city have long vanished and turned into choked drains with little to no maintenance, according to experts.In the 17th century, when Mughal emperor Shah Jahan built his capital in the 1640s, the new city of Shahjahanabad was laid out with drainage. “These were mostly covered drains that most streets used to have, and they used to empty out through some of the major gates,” said historian Swapna Liddle. “The Mori Gate, for instance, served as an outlet for large volumes of wastewater. The Ajmeri Gate side also had channels carrying water out of the walled city,” he added.“Later, through lack of maintenance, particularly as the Mughal empire declined, they became choked up and defunct,” Liddle explained, “By the 19th century, many of the likes of historian and AMU founder Sir Syed Ahmad Khan were already writing that these drains were not working well. A new system had to be put in place.”Even outside the walled Mughal capital, Delhi’s geography used to once offer its own natural drainage.Also Read | Looking at solution for 30 yrs, Govt unveils drainage plan for DelhiExplaining Delhi’s topography, oral historian Sohail Hashmi said, “From the west bank of the Yamuna to the foothills of the Aravalli, the land looks like a piece of watermelon—broad in the middle, narrow at the ends. It slopes downward towards the Yamuna.”Rainwater streams flowed naturally along this slope. From the Kushak Nallah near today’s Race Course Road and Teen Murti to rivulets around Tughlaqabad, nearly a dozen streams once drained into the Yamuna. Along their course, they replenished Delhi’s lakes and ponds. Each monsoon, these natural depressions used to once collect rainwater, which then percolated into the ground, keeping aquifers alive.“In 1947, there were more than 300 such lakes and ponds in Delhi. Today… not even 20,” Hashmi said. “We encroached on them, filled them with garbage, and built colonies on top. Now there is no place where rainwater can go.”Story continues below this adToday, Delhi’s drainage map resembles a web of arteries — each stream branching and curving before meeting the Yamuna. This is because these are not man-made drains, but natural rivulets that have been repurposed as carriers of sewage.Colonial rule too brought profound changes. In the 1880s, the British introduced municipal waterworks in Chandrawal and dug “Renny’s wells”, which were deep pits in the Yamuna floodplain to extract subsoil water before it was pumped to Shahjahanabad. They also introduced the flush system.Also Read | Delhi may witness its first-ever artificial rain as cloud seeding trials likely in October-November“In the 1890s, the municipal committee introduced the flush system and laid underground sewer pipes…Where was the sewage going? Into the drains, and eventually into the Yamuna,” Hashmi said.Initially, the flow of Aravali water into these streams helped avoid diseases like E. Coli as it helped in absorbing the waste. But this system carried the seeds of future collapse. “The killing of the Yamuna was started by the British but we completed it,” Hashmi said.Story continues below this adIn 1947, India-Pakistan partition changed Delhi overnight. Its population first fell from nine lakh to six lakh as one-third of its residents, mostly Muslims had fled. Soon after, eight lakh refugees arrived from Pakistan.How was this influx accommodated? “Those who had papers were allotted land. Those who didn’t simply identified open land and built houses,” Hashmi said.Many such colonies sprouted along the streams that once carried fresh water from the Aravallis.Gradually, as the population increased, the Aravali water flow could no longer dilute the water and these rivulets turned into open drains. The old streams, instead of carrying stormwater, started getting clogged with untreated sewage.Story continues below this adBy the 1990s, even as Shahjahanabad and New Delhi had received a new and planned sewage system, the rest of the city sprawled without coordinated planning.Experts say that the post-independence settlements have disregarded the natural slope of the land.“None of our town planners understood the slope and how crucial it was…if you build a road across the slope, it is unavoidable that the water will collect there …You cannot name one colony built after independence where there is no waterlogging,” Hashmi said.This is why centuries-old settlements like Mehrauli or Shahjahanabad rarely face waterlogging but post-colonial neighbourhoods routinely drown in rainwater.Story continues below this ad“The problem is not just history but also the neglect of what exists today,” said Manu Bhatnagar, Principal Director, Natural Heritage Division, INTACH.“From 1912, since the era of Lutyens’ Delhi, drainage systems were introduced by the British. After Independence, the newly built drainage system has not been maintained,” he added.Bhatnagar concluded, “The problem is twofold: poor upkeep and flawed design. The built drainage system is not maintained properly because it is full of garbage and silt. It shows lower efficiency than it is made for. Further, the city is so concretised that water can no longer seep into the ground. And when the river is in spate, the natural drainage cannot discharge into it because the river level is as high as the natural rivulets. These are the difficulties in Delhi’s drainage.”