Crowdmapping Bengaluru's Vanishing Lakes

For a city famed for its many water bodies, often for the wrong reasons, with lakes spewing fire and noxious foam, there is a lack of reliable records about Bengaluru's vital blue infrastructure.

This data gap has significant impacts on the ground. For instance, the Bruhat Bengaluru Mahanagara Palike (BBMP) recently resumed construction of a road within the buffer zone of the Pattandur Agrahara Lake near Whitefield in the eastern part of the city. Citizens' groups have been fighting to protect the lake, said to be nearly 1,000 years old, while the BBMP claims that they can build in the area as they are not breaking any law.

The BBMP and the district administration both do not have a survey map of the lake, they told the Deccan Herald in December 2021.

Multiple groups--including citizens groups and eight government agencies--manage Bengaluru's lakes. Yet, there is no comprehensive or up-to-date database of the lakes.

This is despite lakes acting as buffers during floods, providing livelihood to fishermen and livestock owners, and providing habitat to various fauna. There are many instances of Bengaluru's loss of water bodies to encroachment, degradation, shrinking or flooding, causing ecological, social and economic damage.

We reached out to the BBMP for information on the Pattandur Agrahara Lake, the number and most recent database of Bengaluru's lake, and whether there is a plan to better map the city's lakes. We will update the story when we receive a response.

To protect existing lakes, the key is to first document them, and then to ensure that these data are publicly accessible. A crowdsourcing initiative, by the Centre for Social and Environmental Innovation (CSEI) at ATREE, a research institute based in Bengaluru, has identified 1,350 lakes spread across Bengaluru.

Gap in data on Bengaluru's lakes

Lakes in Bengaluru were originally built for irrigation and drinking water purposes. As a result, they were governed by local communities who used them as a common pool resource. But, over the years, the lakes have come to be managed by government agencies and the nature of rules governing the lakes have become more formal and uniform.

Given the complex history of governance and stewardship on Bengaluru's lakes, as we said, there is no comprehensive and up-to-date database of the lakes. The public datasets released by government agencies have been created using information from various agencies over the years. These datasets are incomplete and often inaccurate as either multiple lakes are missing or have been marked inaccurately.

Case in point is the original dataset put out by the erstwhile Karnataka Lake Conservation And Development Authority (KLCDA). It does not list all the existing water bodies within the Bangalore Development Authority (BDA) and BBMP limits. The KLCDA list contains names and locations of only around 210 lakes within the BBMP boundary. Researchers from ATREE found a number of issues in this list: Many lakes' locations were marked wrongly, many were missing, while some in the list had been encroached upon or had dried up.

In 2018, the Karnataka government transferred all responsibilities of the KLCDA to the Karnataka Tank Conservation and Development Authority, which falls under the Minor Irrigation Department.

Currently, the most followed and accessible database for the public and for government agencies is the BBMP's list of lakes, found CSEI's analysis and interaction with citizen groups. But this is also incomplete and only covers the area under the civic body's jurisdiction. It lists 167 lakes.

Crowdsourcing lake data

Because most of the government datasets are incomplete, incorrect or outdated, there is a need to verify lakes with historical and present images for each lake.

With the help of citizen volunteers, CSEI at ATREE collated lake data from different sources to identify 1,350 lakes spread across Bengaluru--777 lakes in Bengaluru Urban and 573 in Bengaluru Rural. The Urban Lakes Initiative at CSEI, under which this exercise was conducted, works with communities and organisations to collect and curate data, and thus help protect and restore lakes.

CSEI identified water bodies using geo-referenced toposheets (maps that represent three-dimensional land surfaces) sourced from the Survey of India, and Google Earth aerial imagery. CSEI held six training sessions with 35 participants, who learnt to map and verify the location of existing lakes in the city using toposheets and available government data.

These lakes were then manually digitised after verifying their existence by comparing the toposheets and Google Earth imagery. The final dataset contains the location and boundary of both perennial and seasonal lakes in urban and rural districts. The database has details of the lakes' location, boundary, area, custodian details, ward details and citizen lake groups involved in their management.

Bangalore Lakes Masterlist, created by Shashank Palur and Rashmi Kulranjan, Centre for Social and Environmental Innovation, Bengaluru

The identified lakes are named as per the names on the toposheet or according to the settlement nearest to the lake. This will be updated with access to more government records as will the dataset as more details become available. (If you have more recent information on these lakes, use this form to contribute to this open source project.)

A snapshot of the list of lakes and details collected for each. Credit: CSEI-ATREE

A screenshot of a toposheet with the mapped lakes. Source: CSEI-ATREE

Why it is important to fill the lake data gap

The crowdmapping has been turned into a shareable map, which can be used by both government agencies as well as citizen lake groups as a reference. This can enable different stakeholders to make informed decisions about the management of lakes and how to proactively safeguard them.

Currently, clarity on the number of lakes in Bengaluru Rural and Bengaluru Urban districts are missing from government records, said Kaustubh Rau, a biologist documenting Bengaluru's lakes, and a researcher at Azim Premji University (APU), and Ayushi Biswas, a research associate at APU. "Detailed studies on lakes around Bangalore have been not possible due to unavailability of digitised and georeferenced lake data."

Crowdsourcing this work not only sped up the process of discovering and mapping lakes but also made citizens an active part of data gathering and helped them appreciate the complexity of establishing a comprehensive database of lakes that can enable conservation, CSEI found.

This exercise also showed the grim reality of how many lakes had been lost over time due to poor management and underlined the urgency to identify existing lakes before they too are built over. Compared to the 2011 toposheet, which marks 1,558 lakes, about 208 lakes appear to have vanished over a decade, CSEI, which mapped 1,350 lakes, found.

Open access data of this sort will allow the flow of information between government bodies and the public more easily and crowdsourced maps could be a great starting point for monitoring, supervising and planning restoration projects by both citizens and governing agencies.

It will help more citizens come forward and collaborate with the government, said Shobha Ananda Reddy, a designate at the Indian Administrative Fellowship under the Karnataka government's panchayat department, and an environmental scientist, who reviewed the dataset. She is also the managing trustee of Jalmitra, a citizens' group working for the revival and maintenance of Rachenahalli lake.

"Usually stakeholders will have information pertaining only to their area of work. For example, the BWSSB focuses on underground drainage; the BBMP's storm water division has only information related to storm water flows etc," Reddy said. "I am optimistic that the database will also enable and simplify the coordination among various stakeholders."

The database can also help identify seasonal lakes, dry lakes or dry wetland areas, which is necessary considering a lot of lakes in Bengaluru are seasonal and dry up completely during the summer, and might not be identifiable as lakes, added Rau and Biswas of APU.

One of the big problems hampering integrated urban water management is that different stakeholders are not working off the same base data for a wide range of activities, experts said. For example, urban planners need to know where to build sewage treatment plants, where flooding is likely to happen and conduct land suitability analysis before planning to expand existing cities. Students want to do research; citizen groups want to save their local lakes.

Data being collected and managed in silos, and being largely inaccessible for the public, is not a problem unique to Bengaluru, which is why it is necessary to explore the potential of replicating this exercise in other cities.

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