Indian cities are increasingly facing the adverse impacts of urbanisation, erratic rainfall, and climate change, leading to frequent seasonal flooding, water shortages, urban heat islands, and the disappearance of natural water bodies. Existing urban infrastructure lacks the capacity to manage water sustainably. There is an urgent need for innovative, nature-based solutions like the sponge city concept to enhance urban water resilience by mimicking natural water absorption, filtration and storage processes within the built environment. Read on to know more…
As Sachin Joshi, a specialist in water and sanitation engineering, notes, “The sponge city approach allows the landscape to become part of the water infrastructure, helping cities retain what they used to repel.”
The term ‘sponge city’ was first popularised by Chinese landscape architect Professor Kongjian Yu in 2013, who envisioned a
new approach to urban planning that embraces nature rather than suppresses it. Since then, the model has gained international recognition and has begun influencing how Indian cities think about water. From Andhra Pradesh to Tamil Nadu, cities are exploring sponge infrastructure as part of their long-term climate resilience and sustainability agendas.
Why Sponge Cities Matter
Sponge cities address several core urban challenges:
- Monsoon flooding due to poor drainage and excessive runoff
- Declining groundwater levels
- Water pollution from untreated sewage and solid waste
- Urban heat islands caused by excessive concrete surfaces
- Lack of open green spaces for recreation and biodiversity
By integrating water-sensitive design and nature-based infrastructure, sponge cities offer multifunctional benefits that go beyond flood control.
ANDHRA PRADESH
One of the most ambitious sponge city initiatives in India is underway in Andhra Pradesh. The state has identified 64 water bodies across 15 cities for rejuvenation under a longterm water resilience plan.
Key components of the initiative include:
- Cleaning and restoring polluted lakes
- Preventing sewage and industrial waste from entering water bodies
- Removing encroachments and improving public access
- Diverting stormwater through natural and engineered channels into lakes
- Installing decentralised treatment systems at discharge points
“The revival includes multiple layers of work desilting, setting up edge zones for biodiversity and integrating sensors to monitor water quality.” Co-treatment is crucial in such projects, where both domestic sewage and industrial waste are
treated through upgraded Sewage Treatment Plants (STPs) before the water is recharged. “Without safe treatment, recharge can become contamination,” explains Sachin.
CHENNAI
In Tamil Nadu, the Greater Chennai Corporation (GCC) has proposed the development of 64 sponge parks across floodprone
and water-scarce areas. These parks will be designed to:
- Capture rainwater through underground trenches
- Use pervious surfaces and bioswales to reduce runoff
- Filter and store water for reuse in landscaping and groundwater recharge
- Create green zones that reduce surface temperatures and provide public amenities
These sponge parks reflect a shift in how urban green spaces are being perceived—not just as beautification projects, but as functional assets in water management and climate adaptation. However, Sachin cautioned, “Sponge parks will only work if we plan for both function and safety. Runoff water must not stagnate and should be filtered efficiently, especially near schools
and residential areas.”
Effective sponge city planning hinges on understanding the underlying hydrogeology. Sachin stressed the importance of geospatial and geoelectrical mapping to identify viable recharge areas. “It is crucial to understand aquifer interconnectivity. Without scientific surveys, recharge may not be effective or could lead to waterlogging and salinity issues.”
Integrating stormwater systems with decentralised recharge pits, bioswales, wetlands, and infiltration trenches can maximise percolation, but only if guided by localised data. This approach prevents both overloading of storm drains and under-utilisation of recharge potential.
Green-Blue Infrastructure: Tools of a Sponge City
Sponge cities employ a combination of green and blue infrastructure, including:
- Rain gardens and vegetated swales to slow down and filter runoff
- Permeable pavements to enable infiltration
- Restored wetlands for water retention and biodiversity
- Green roofs and vertical gardens to absorb rain and reduce heat
- Urban ponds and lakes connected to stormwater drains
- Treated greywater reuse for landscaping and cleaning
Each component not only manages water but also improves the aesthetic and ecological quality of urban spaces. These elements are being included in several Smart Cities projects and are being aligned with missions like AMRUT 2.0, Jal Shakti Abhiyan, and the National Mission for Clean Ganga.
OTHER CITIES
- Hyderabad is examining ‘sponge neighbourhoods’ with a focus on flood-prone areas.
- Kochi’s city resilience roadmap includes decentralised sponge systems, expanded greenery, and improved drainage.
- Gurugram is looking to integrate sponge planning into its development regulations, particularly in zones around natural drains and water bodies.
In each of these cases, a layered approach is being taken—combining natural infrastructure with policy reform, public engagement, and smart monitoring systems.
Despite its promise, sponge city planning faces several constraints:
- Limited inter-agency coordination among municipal departments
- Resistance to changing traditional stormwater and building norms
- Inadequate data on water flows and aquifer systems
- Lack of trained urban designers and engineers familiar with sponge infrastructure
- Land availability in dense city cores
To overcome these, Sachin recommends building institutional capacity. “Urban engineers need to be trained to design and maintain green-blue systems. We also need clear technical guidelines at the city level, on everything from slope design to water retention times,” he said.
There is also a pressing need to engage citizens in sponge infrastructure. Public parks, roadside greenways, school campuses, and even individual housing layouts can be transformed into microsponges that contribute to broader city-scale resilience.
The sponge city model offers a practical and locally adaptable framework to address India’s urban water crisis. Rather than investing solely in large capital-intensive water infrastructure, cities can leverage the power of nature — combined with science and policy — to build urban systems that are not only more sustainable, but also more humane. As Sachin rightly sums up, “A sponge city does not just manage water; it reimagines the city as part of the water cycle itself.”