Mapping Mumbai's water supply

The construction of a visual map of water supply to Mumbai city from available data sets on water quality and water related infrastructure by NEERI as a part of the data project started by India Water Portal, Arghyam was a challenging task.

The visualisation process

The representation of the datasets needed to bring together the water quality of the city, mapped over its existing infrastructure. It needed to present relationships of the various stages of water flowing from source to the taps inside the homes. Such a visualisation of data would require it to be laid onto a system map, so that it would be easy to plot the movement of water from one stage to another. While a map of the water supply system was found with relative ease, it was also surprisingly illegible and filled with details of little relevance. Also, since these maps did not carry a time stamp, it was often difficult to verify the information they presented.

The need for a Mumbai base map

This made it necessary to create a good reference map over which the data for water quality could be traced. Excessive details such as the road network of the city, or landmarks such as parks and important buildings that helped to orient the reader, needed to be weeded out as they made it harder for the water infrastructure to be mapped with desired clarity. However, since the data was closely linked with different locations around the city, it was necessary for the visualisation to retain some geographical relevance. The maps produced consisted of various water bodies that made up the water supply infrastructure of the city and included reservoirs, lakes, treatment plants, tanks, and so on.

Limitations faced with the Mumbai data

The NEERI report for Mumbai was inadequate in providing sufficient information about the sources, treatment facilities, the distance they travelled and the distribution of raw water between the water treatment facilities to make up for an accurate system map. Names of certain water sources, too, were inconsistent across various documents and made it a little hard to trace them over a geographical reference map. The map provided in the CDP, prepared for JnNURM, had poor legibility in the procured copy, but was useful nontheless in understanding better the water movement from source to treatment plants. 

We unfortunately couldn't overlay the water quality data on top of the system map. 

Methodology

The visualisations were produced using information primarily from the reports produced by NEERI (National Environmental Engineering Research Institute) and a from a sense of relative proximity in representation of the various elements that made up the water systems of the chosen cities. The information provided by the reports was further corroborated with additional sources such as water governance boards and government reports, and changes were made accordingly. The maps also needed to incorporate information on distances and the paths traced between various bodies of infrastructure. The details have been expanded upon in the text below:

NEERI Reports

The reports produced by NEERI served as a point of departure for the visualisations. The structure of the report was as follows:

• Introduction to the city
• Sources of its raw water, path to the treatment facilities, and distribution of treated water 
• Water treatment plants, the processes they deploy, and staffing composition
• Sewage treatment as well as dry waste management.

The information from across the report provided the base on which the framework for the visualisation was built. Every water body and treatment facility was identified before connecting the appropriate units to each other. This also included mapping out the unique distribution system for every city. 

Additional Sources

The research undertaken by NEERI for the reports predated the projects proposed and implemented with funds from the JnNURM (Jawaharlal Nehru Urban Renewal Mission). CDP’s (Comprehensive Development Plan) were produced for the same. The CDP’s, thus, formed another source of information to supplement the original NEERI reports. Many water treatment and distribution boards also had some information relevant on their website, mostly in the form maps, that were found quite useful as well. In some instances, academic papers, too, were referred to.

Google Maps-based distance calculators

Once the basic structure was constructed, the relative distances were mapped approximately on the diagram. However, certain liberties were necessitated to communicate scale and the intricacies of the systems. A large number of reservoirs/treatment plans/dams had been mentioned in the report without making clear how far they were from the city. Distance calculators were used to approximate distances from the city’s centre. 

Limitations faced while constructing maps

While the set of NEERI reports covered extensive ground in most cases, it also revealed inadequacies in information provided when corroborated with other/recently updated sources. More importantly, although the reports followed a structure in presenting their findings, the level of information within each section varied from city to city. This made it difficult, at times, to work with the report. 

The maps were designed to be very simple so that they engaged the reader to have a conversation about the data and its revelations, be it the state of the water one consumed or the data that evaluated it. The glaring lack of data became increasingly apparent once the mapping began. Putting together such a map was riddled with problems of availability and accuracy of data

*Maps done by Tejas Panda, Consultant with IWP