Why Delhi must invest in blue-green infrastructure

Delhi needs to opt for smart water use and conservation. Green infrastructure is gaining traction in the city, but the government must also make blue infrastructure an integral part of its sustainability plans

If the recent round of extreme climate events in Delhi — abnormally high temperatures between March and May and erratic monsoon rainfall — are any indication, the Capital is in trouble. With the climate crisis footprint becoming bigger and bigger every year, it is vital for the city — a key political, economic, and cultural hub of the country — to adapt to the vagaries of the climate crisis.

While blue indicates water bodies such as rivers and tanks, green spaces include trees, parks, and gardens. Together, these spaces can address a host of urban challenges. (Shutterstock)

While there is an array of climate adaptation measures available, the city government would do well to invest heavily and judiciously in a blue-green infrastructure strategy to address these climate extremities effectively and protect its citizens and the thriving economy.

The scope of characterisation of blue-green infrastructure may vary in India, as per its national, state, or regional features. However, blue infrastructure is usually used to indicate the utilisation of customised, footprint-lean, efficient instruments installed or retrofitted into conventional water-collecting systems.

While blue indicates water bodies such as rivers and tanks, green spaces include trees, parks, and gardens. Together, these spaces can address a host of urban challenges. While rain barrels and tiny green roofs make small-scale systems, enormous stormwater catchments represent large-scale blue-green infrastructure systems.

Over the past two decades, several blue-green infrastructure systems have been implemented worldwide to solve water-related urban problems. The Active, Beautiful, Clean Waters Programme of Singapore could interest Delhi as it focuses on holistic stormwater management.

Over the years, Singapore has created a widespread network of around 8,000 km of canals and 17 reservoirs for its water supply. The programme aimed to clean streams, rivers, and lakes by integrating drains, canals, and reservoirs. There was a paradigm shift in Singapore’s water governance with approaches of capacity building and community incentives.

The Grey to Green Initiative in Portland, Oregon, United States, is also relevant as it focuses on clean rivers through blue-green infrastructure. The strategies involved creating green streets, eco-roofs, street and yard trees, replacing culverts, re-planting, and removing invasive weeds.

Delhi’s water dynamics depend on blue-green infrastructure and have been envisaged in the draft Master Plan for Delhi 2041. The Capital city has 50 drain networks managed by different government departments. However, the drains are in poor condition, and the land around them has been encroached on by illegal colonies and markets. The drains were built to capture rainwater but are now filled with sewage and other waste.

Delhi needs to opt for smart water use and conservation. Green infrastructure is gaining traction in the city, but the government must also make blue infrastructure an integral part of its sustainability plans. In addition, adaptation and resistance to the climate crisis necessitate protecting and preserving the urban landscape’s hydrological and biological features.

The city must also develop infrastructure to capture and clean rainwater with the help of green roofs, permeable pavements, bioswales, rain gardens, modular systems, engineered wetlands, and absorbent landscapes to achieve water conservation goals.

To realise the full potential of an established drainage network, the city could focus on premise-based retention methods with active community involvement. These could be made effective by developing infrastructure to collect, treat, and store stormwater.

The collection of stormwaters could be done by constructing waterbodies, urban plazas, open fields, and building features. Water treatment would require effective infrastructure such as sedimentation basins, constructed wetlands, and vegetated and/or bioretention swales. Delhi also needs to explore the retrofitting of the present infrastructure, and it would require an extensive inventory of blue-green infrastructure. The city government must invest in building such an inventory since it will help build resilience to the changing climate.

Charu Bhanot is a research associate, and Sonia Grover is a fellow at The Energy and Resources Institute in New Delhi

The views expressed are personal