Bengaluru's civic body needs to stop relying on British-era maps, embrace satellite imagery instead

After last week’s flooding, Bengaluru witnessed five straight days of demolition of buildings that were allegedly built on or obstructing old storm water drains, secondary and tertiary drains, which once helped excess rainwater flow unhindered.

The sight of bulldozers passing on the streets have created large-scale panic in India’s Silicon Valley, whose civic body, Bruhat Bengaluru Mahanagara Palike (BBMP), in an obvious display of irony, still relies on British-era maps.

The officials, armed with these survey maps that date back to the 1900s and platoons of riot police, have descended on these alleged encroachments and have left thousands of houses and apartment blocks–—in which residents have been living for years and paying property taxes—quickly reducing beautiful residences into rubble.

The exercise, city officials said, is the only way they could rebuild lost waterways and prevent any future flooding.

But, the situation of flooded roads as a result of poor planning is not unique to Bengaluru alone. Rainwater flooding has become the bane of urban life, as witnessed this week across Gurgaon, Mumbai, Chennai, Patna, Kolkata, Jaipur, Hyderabad and other smaller cities, prompting the question as to why none of these city governments have mapped their growth accurately using satellite imagery or Geographical Information Systems (GIS).

The Google Maps app is widely employed to seek directions within cities or to navigate highways, and employee transportation companies accurately map pick-up and drop locations using latitude-longitudinal coordinates. But, civic bodies show little interest in mapping drains, roads, footpaths, parks, residential and commercial zones, despite a whole family of Indian Space Research Organisation (ISRO) satellites available at their disposal.

The ISRO satellites have been mapping India for both what is under the ground as well as overground. For example, we know under which parts of India thorium deposits lie or how much green cover has dwindled in the last three years. But we are unable to harness the same technology to keep watch over the unbridled growth of cities. Of course, there is access to such imagery—the Indian Institute of Science in Bengaluru has mapped the city’s growth over the years—but there have been no efforts to use them to accurately correspond with older maps of cities–like the 1902 survey maps that the BBMP uses as its guiding beacon to demolish citizens’ properties.

After every rain, civic bodies in Gurgaon, Bengaluru, Chennai or in Mumbai prefer to use shovels and pickaxes to clear drains and threaten encroachers with eviction notices, instead of taking up a programme to use available technology and clearly demarcate civic utilities.

BBMP Commissioner Manjunath Prasad said the drain network was being mapped on GIS and will be ready soon. This will be superimposed on older survey maps and this indicative map will be put in the public domain.

The State government too has been supporting the demolition, or what has come to be called `demonising’ drives, on the ground that the Karnataka High Court had ordered to clear encroachments.

ISRO officials YourStory spoke with said the space agency has a series of low orbiting satellites, whose cameras have a three-metre or lesser spatial resolution – meaning the detail discernible in an image is dependent on the spatial resolution of the sensor, and refers to the size of the smallest possible feature that can be detected in any satellite image.

With such accuracy, these satellite images can be superimposed on old Geological Survey of India maps to identify the original routes of the stormwater drains, and help literally unearth lost lakes as well as water bodies. If this is done, then the recent ruling of the National Green Tribunal’s (NGT) order that no construction activity be allowed in the buffer zone of urban water bodies can be validated too.

A senior ISRO official, who spoke on the condition of anonymity, said ISRO had developed good remote sensing capabilities and these high resolution geo-spatial images can be used by urban planners. He stressed the need for commercialisation of such imagery with the help of the private sector.

Such a move will also help open up revenue channels for ISRO, which has developed a mapping software application called Bhuvan. Explaining further, the official said, Cartosat-2C, an earth imaging satellite with a sub-metre resolution, was launched on board the PSLV last month.

We are already gearing up to build and launch next-generation cartography satellites having a 0.25-metre resolution, which will be ideal for urban planners. Such satellite imagery can help map the entire country and render old survey maps obsolete.

Explaining further, the official said, Cartosat-2C, an earth imaging satellite with a sub-metre resolution, was launched on board the PSLV last month. "We are already gearing up to build and launch next-generation cartography satellites having a 0.25-metre resolution, which will be ideal for urban planners. Such satellite imagery can help map the entire country and render old survey maps obsolete.”

Such imagery, when superimposed on these old survey maps, can detect encroachments and help arrive at a reasonable cut-off date to regulate the so-called unauthorised construction.

After the current round of demolitions, there has been an increased call for pulling up those officials who allowed these encroachments to happen in the first place.

AT Ramaswamy, a former MLA, who earlier headed a joint legislature committee on encroachment of government land in Bengaluru, explained that without the active connivance of government officials, such detailed property documents cannot be prepared. He added,

Now, poor innocent buyers who invested their life savings are suffering. Stringent action should be taken on such officials and builders too should not be spared.

Already, 3,000-plus properties have been identified as encroachments and notices have been despatched. The current chairman of this committee is Karnataka Assembly Speaker KB Koliwad, who opined that no mercy should be shown to officials who duped people by issuing khatas (property ownership papers) for these properties. The committee is looking at the prospect of lake encroachments in Bengaluru district, which comprises both urban and rural areas, and will recommend strict action to the government on encroachers.

The earlier buffer zone for lakes and wetlands was 30 metres but after it has been extended to 75 metres by the NGT, this automatically puts buildings as old as 20-25 years in question, and an entirely new set of problems is bound to crop up across India.

This is where upgrading to satellite imagery will help civic bodies across the country perform better.