Using GIS to strategically treat contaminated water and prevent disease outbreaks (Chennai, India)

December 23, 2015
5 min read


In 2015 the Chennai district in India experienced severe flooding. To quickly eliminate the threat of disease outbreaks from contaminated water across the district, volunteers decided to use online GIS and strategically apply a sanitation agent.We talked to one of the volunteers included in the Chennai Silver Lining – A Sanitation Drive project. Read a story about a great community initiative of Chennai’s citizens who decided to organize to reduce health risks the flooding posed to Chennai’s population.


Community Sanitation Project – an Action Plan for Emergency Relief



A group of volunteers led by Mr. Sai Shankar decided to initiate the Chennai’s Silver Lining project after the heavy rainfall from Nov 30 to Dec 2 in 2015, which caused severe flooding that posed significant health risks for the Chennai population.

They wanted to prevent the post-flooding epidemic breakout by reaching out to every corner of the Chennai district with a 7 days action plan, to sanitize the water deluged area with bleaching powder. Chennai Silver Lining project needed over 100 volunteers to cover different parts of this megacity district. They used guidelines about post-flood emergency health precautions – community sanitation from Disaster Management Education Planning & Training (ADEPT). The idea was to prevent outbreaks of diseases like typhoid, dysentery, infectious hepatitis, and other diseases associated with floodwaters.


Applying a Sanitizing Agent Across the megacity to Eliminate Bacteria in Water


Cleanup procedures included using a sanitizing agent such as hypochlorite in the form of bleaching powder or commercial household bleach, which is the most widely accepted, safe and effective sanitizing agent. Hypochlorite is used for eliminating bacteria, viruses and fungi during the cleanup process.


It is important to act quickly during a flood relief to prevent the spreading of pathogenic organisms. They will not become airborne as long as the surfaces they have contaminated remain wet. Pathogenic organisms can enter the body and cause disease through water splashing into the mouth, mucous membranes, open cuts, etc. Once dried, organisms can spread on dust particles by air movement. That’s why it is important to “sow” the bleaching powder into all wet and marshy areas, and bring all contaminated surfaces into contact with the bleaching powder as soon as possible.


Marking HUB points on a map to organize volunteers


Volunteers needed to act quickly and those with the experience in GIS decided to use a cloud-based mapping solution to achieve fast and effective team coordination. They used GIS Cloud’s Map Editor to create a map with HUB points, with the location name, address and contact number.

This way they could plan which team will dispense the sanitizing agent in specific areas of the district. Later, this map was published through the GIS Cloud Map Portal to be easily accessible to a wider public and volunteers. Learn more about the Map Portal here.

Chennai volunteers were motivated to implement a Silver Lining project after they have studied the dangerous after-effects of flooding. They decided to help their community by organizing themselves to participate in flood relief.

Volunteers have organized 13 HUB stations, marked on a map, for different areas of the Chennai district and conducted the project with the help of Chennai’s community. The full number of volunteers and the percentage of the sanitized area still isn’t available, but project participants claim that the Chennai Silver Lining achieved a community-based success that proved the strength of unity in extreme circumstances.


Chennai Map


Importance of GIS in Disease Prevention


This project offers a good example of a community-based initiative that highlights the importance of spatial thinking in disease prevention. Roots of using spatial thinking in risk management in the case of the disease date back to the 19th century when Dr. Snow used a map to find the source of the cholera outbreak. In the 21th century, we have various web mapping tools which can do the same, and more.

Chennai Silver Lining project volunteers agreed on the importance of education for encouraging the spatial thinking of students, policy-makers, government, and NGOs, because “prevention is better than cure.” In this case, GIS proves to be a great decision-making tool that can be used for any risk and mitigation plan.

They believe that GIS can be extensively used to re-survey the complete land use and land cover of the Chennai district to make a digital copy/map of the area. Volunteers would like the Metropolitan authorities to have this map for future decision-making and coordination activities, initiating research and development in the National Disaster Management. This map should be available to the public, being a good start in encouraging spatial thinking for all the people.

Chennai Silver Lining project serves as an exemplary case for both GIS and non-GIS experts that want to do something for their community by applying spatial thinking and spatial knowledge to a specific project or cause.

Cloud-based GIS tools are a great way for volunteers in different initiatives to organize themselves, collaborate, and improve their decision-making, with the help of technology. You can browse the Chennai volunteer’s map here.

If you want to start using online GIS to tackle your disease prevention or other environmental projects, create your account and learn as you go.



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