Eight people, including two toddlers, were killed when a portion of Kurla’s Hill Number 3 came crashing down on four shanties on August 12. A month earlier, six people, including five minors, were killed when a four-storey structure in Mankhurd collapsed onto adjoining shanties.In both cases, the Brihanmumbai Municipal Corporation (BMC) said it had warned residents to vacate on safety grounds. Yet the people remained. And after the deaths, the BMC and the Mumbai Collector’s office again pointed to each other over who was responsible for removing them.This has become a recurring pattern in Mumbai. Identify settlements at risk, issue notices, leave people in place, and after a disaster, debate which agency had the authority to act. It is not new.In July 2021, 29 people were killed in two separate landslides in Vikhroli and Chembur when portions of hill slopes collapsed onto adjoining shanties.The problem is not that the city does not know where the risks are. Kurla’s Ashok Nagar was a BMC-designated landslide-prone zone, with residents warned to vacate before the monsoon. (Express Photo: Deepak Joshi)In 2018, the Geological Survey of India (GSI) submitted a 435-page risk assessment report to the BMC identifying 45 highly vulnerable, inhabited landslide-prone locations across Mumbai. The report noted that the city had recorded six major landslides between 2000 and 2016, which claimed 119 lives.Eight years later, the disasters continue. The BMC’s Mumbai Climate Action Plan identifies 287 landslide-prone locations, of which 209 are within informal settlements. More than 340 people have been killed in landslide incidents reported in these areas between 1992 and 2026, according to BMC data.Story continues below this adThe question is not why people continue to live in dangerous locations. It is why a city that has mapped them has built no system to make them safer or move the people out.A warning is not an evacuation planAlmost all of Mumbai’s hills are government land under the Collector’s office and the state revenue department. These are concentrated largely in the eastern suburbs, where rapid urbanisation led to settlements spreading onto hill slopes, ridges and former quarry sites.The GSI classified hills in Kurla, Vikhroli, Bhandup, Chembur and Ghatkopar among Mumbai’s highly vulnerable landslide-prone zones. Despite the known risks, local authorities carry out no regular risk assessments. The process largely involves issuing notices warning residents they live in landslide-prone areas. These notices are informational and stop short of eviction or enforcement.That leaves a basic question unanswered. What happens after the notice? A civic official said, “The land on which these structures stand doesn’t fall under BMC’s jurisdiction; therefore, we cannot carry out an enforcement drive without the collector’s authorisation.”Story continues below this adAn official in the Collector’s office pushed back, “For Mumbai, the BMC is the primary planning body, and the collector’s office doesn’t have any resources to carry out such a large-scale eviction drive.” So the two agencies agree on the danger but differ on who has the authority and resources to act.After the August 12 landslide, municipal commissioner Ashwini Bhide said the hills were designated non-development zones under the Mumbai Collector’s jurisdiction. Mumbai Suburban Collector Saurabh Katiyar maintained that the BMC is the authorised District Disaster Management Authority in Mumbai, leaving his office limited authority to carry out eviction drives. The result is a gap between warning people about a known risk and removing them from it.How Mumbai’s hills were encroachedMumbai chronicler and Khaki Tours founder Bharat Gothoskar said more than 60 per cent of South Mumbai’s landmass was reclaimed from the sea, with rock and soil quarried from hills across the city. “Once a hill was quarried, the abandoned quarry was squatted upon by underprivileged migrants coming to the city. These shanties lacked basic facilities and were unsafe, as the half-quarried hills would collapse during heavy rain. As the city expanded, these once-out-of-the-way places became part of the city but continued to remain unsafe,” Gothoskar told The Indian Express.After Independence, Mumbai absorbed a huge influx of people from Maharashtra’s hinterland and other parts of the country, many drawn by jobs, including in the textile mills of central and south-central Mumbai. As the population grew, settlements spread up hill slopes, many of them former quarry sites where excavation hadStory continues below this adaltered the gradient. Houses went up close to the slopes, in some cases cut into the hill face.For residents, the risk came with a trade-off, lower rents in a city where affordable housing is scarce. The Mankhurd-Shivaji Nagar belt illustrates the other side of the problem. Beside the Deonar landfill, the area has long offered cheap housing. Much of Mankhurd and Govandi was developed on reclaimed land, marshes and filled-up dumping grounds. The soil has low bearing capacity and weakens when saturated by heavy rain, raising the risk of structural settlement and collapse.As the government land stayed unused, it was gradually encroached upon. “These houses were not built in a day. Without the government’s authorisation, a person cannot even erect a shanty, and here lakhs of people have been living for decades. This is a man-made issue and clearly reflects the lack of an affordable housing scheme in the state that has pushed people to live in these conditions,” said Bilal Khan, a Mumbai-based housing rights activist.A policy that never moved off paperThe GSI’s 435-page assessment recommended a specific land-use policy for Mumbai’s hilly areas. It remains unimplemented. “For planning purposes, our recommendations to the BMC and state government were to frame a land-use policy and a hill area development policy that would include a set of directives on what types of civil and development works should be permitted in hilly areas,” a GSI official told The Indian Express.Story continues below this adThe report itself warned that land-use planning and construction policies were essential in landslide-prone parts of the city, and should not be violated, because the loss in a disaster would be immense if buildings were not safely located.The contrast with other hilly areas is stark. The Building Materials and Technology Promotion Council, under the Ministryof Housing and Urban Affairs, recommends buildings in landslide-prone areas sit well away from steep slopes. Nainital’s municipal rules prohibit construction on hilly areas where the natural slope exceeds 26.5 degrees. Uttarakhand’s limit is 30 degrees and Himachal Pradesh’s is 45 degrees.Hill Number 3 in Kurla, where the August 12 landslide occurred, has slopes ranging between 65 and 75 degrees, according to the GSI report. Its slopes and ridges are packed with multi-level housing structures located close to one another.Story continues below this adThe danger is not just the rainThe immediate trigger may be heavy rain. But experts say the underlying vulnerability is often man-made. Deepankar Choudhury, a geotechnical engineer and professor of civil engineering at IIT Bombay and chairman of the Technical Advisory Committee on Disaster Resilience and Capacity Building to the Maharashtra State Disaster Management Authority, said unplanned construction makes urban slopes more unstable.“The hill slopes in an urban area get overloaded whenever there is erratic, unmonitored and unplanned construction on them. The more weight you put on the slopes, the more unstable they become. Therefore, a heavy rainfall situation acts as a trigger, causing the slope to fail and bringing down landmass in the form of rocks and debris,” Choudhury told The Indian Express.“However, heavy rainfall is only a triggering factor, and the underlying issue is largely man-made in urban areas. For example, housing units built on slopes obstruct the natural flow path of water. Therefore, whenever there is excessive rainfall, water starts following its original path, which can lead to the collapse of these houses or the landmass above them in the form of landslides, causing huge damage,” he added.And the trigger itself is becoming more consequential. BMC data shows that over the last six years, the average rainfall recorded during very-heavy rainfall events has increased from 132 mm to 182 mm. Over the last 10 years, intense spells of very heavy rainfall lasting four hours or more have occurred 28 times.Story continues below this adThis year, despite a forecast of below-normal rainfall, Mumbai recorded three instances of rainfall exceeding 100 mm in 24 hours in the first eight days of July. IMD data shows the city recorded 66 days of rainfall exceeding 100 mm between 2021 and 2024, compared with 52 such days between 2018 and 2020.Ashutosh Kumar, assistant professor of geotechnical engineering at the School of Civil and Environmental Engineering at IIT Mandi, said Mumbai’s rainfall pattern had changed sharply.“For example, three or four years ago, if 500 mm of rain was expected over 30 days, the rainfall would generally be distributedmore uniformly. However, over the past few years, we have seen the city receive 100-200 mm of rain in one or two days, while only 20-30 mm is recorded on the remaining days. Since rainfall during these few days becomes intense, it immediately triggers vulnerable locations, leading to landslides or other disasters,” Kumar told The Indian Express.Story continues below this adWhy the city cannot simply evict everyoneThe cycle persists for another reason too. Removing people from dangerous land is not as simple as issuing an eviction order.Former bureaucrats who held the position of municipal commissioner and key positions in the state disaster management cell said bureaucratic hurdles, legal protections and the absence of alternative housing make large-scale relocation difficult.“In the landslide-prone areas of Mumbai, more than 50,000 to one lakh people are residing at present. As per court rules, the administration cannot directly evict people living in slums if they have been residing there since before 2014, and most of the people living there predate the cut-off date. Therefore, the only possible way to relocate them is to provide alternate housing, which would require a mammoth amount of resources. Also, in a city like Mumbai, there is hardly any large land parcel available where such a large number of people could be rehabilitated,” a former bureaucrat said.But relocation is only one part of the problem. Another former bureaucrat said eviction alone would not provide a long-term solution. “The possible long-term solution is to install geo-nets on landslide-prone areas or construct retaining walls. The Slum Rehabilitation Authority (SRA) is the nodal agency that should be undertaking such work, but it does not have the expertise to carry it out. The BMC or MHADA cannot undertake the work either, since there is ambiguity over who would bear the cost. Therefore, these measures remain stuck in limbo for prolonged periods,” the bureaucrat said.Rajnish Ranjan, a former senior consultant to the National Disaster Management Authority and a disaster management expert, said the NDMA’s landslide mitigation programme prescribed both structural and non-structural measures.“Structural measures include the construction of retaining walls and installation of geo-mesh nets on cliffs, while non-structural measures include rehabilitating people living in at-risk zones and conducting regular risk assessments of slopes. These measures are largely followed in the northern and north-eastern parts of the country, but in Mumbai, there are glaring gaps,” Ranjan said.What happens after Sept 30?The administration now says it intends to break the cycle. On August 14, at The Indian Express’s Idea Exchange, Bhide said the BMC would launch a post-monsoon drive with the Collector’s office to remove illegal structures from landslide-prone areas.The BMC will identify the most vulnerable locations using the GSI report. Where residents refuse to leave after being served notices, Bhide said, the civic body may resort to forced eviction.“Providing alternate accommodation for encroachers cannot always be possible, especially when a city has maxed out on its space and capacity. At some point in time, we will have to implement forceful eviction of illegal encroachers by following all stipulated rules that are in place,” Bhide said, responding to a question on the Kurla and Mankhurd deaths, in both of which the BMC had said it had issued notices to residents to vacate, citing safety concerns.“After the monsoon gets over, we will issue notices to illegal encroachers and ask them to vacate the premises first. If required, forceful eviction will be carried out,” she said.The BMC and Collector’s office have already met on the proposed joint drive. Under the arrangement, the Collector’s office will issue notices, and the BMC will deploy manpower.Katiyar said his office had already begun the drive. “The court does not permit us to remove residential structures during the monsoon season. Therefore, as of now, we have removed hundreds of illegal commercial structures adjoining the Govandi-Mankhurd-Mandala areas, and the drive to remove residential structures will start after September 30,” he said.