It is monsoon time and Delhi has flooded again. A couple of days before, Mumbai under deluge with horrific images of some of the areas of the city underwater.

During monsoon, rivers tend to swell in their flood plains. Lakes and wetlands retain excess surface runoff, while forested lands help in soil retention and groundwater recharge.

Such key components in a natural system help to dampen the impacts of floods, but often the functioning of a city interferes with this natural system. But over the years, we have seen unprecedented downpours between just one or two days which are essentially a climate change phenomenon.

The land use and land cover changes caused due to urbanisation occur at the cost of building on open spaces, green areas, and water bodies. The process of converting the crucial blue and green spaces into impervious layers impedes the natural flow of streams, connected lakes and groundwater recharge.

Development projects such as metro construction in Mumbai, Hyderabad and Bangalore are taking place at the expense of cutting trees. Plans for reclaiming land along Mumbai’s coastline for the construction of a coastal road could potentially hamper the retention of seawater during high tides.

Over the years with the growth of the city, several lakes and the connecting natural drains in Bangalore and Hyderabad have vanished because of encroachment. Within the flood plains of the Yamuna River, Delhi has created a built-up area, which effectively reduces the extent of the river’s flood plains.

Cities are expanding and engulfing the open areas which were major drainage points or forests in the past. We see this happening in most of the cities in India. So, when there are excessive rains, cities are not able to drain the water and hence many areas get inundated.

Mumbai's coastal road project. Photo credit: Aaran Patel

Is climate change the cause?

The answer is both yes and no.

Yes, because global warming has already reached 1degrees Celsius above the pre-industrial level, due to past and current greenhouse gas emissions. There is overwhelming evidence that this is resulting in profound consequences for ecosystems and people.

Climate change is here and now. One of the key manifestations of a changing climate is rainfall variability. The frequency of extreme events such as high-intensity rainfall (high precipitation over a short duration of time) has increased in the Indian subcontinent.

This year, within the first five days of August, Mumbai received about 78% (459.3 mm) of the entire month’s rainfall. In Delhi, the precipitation on four discrete days in July and August was about 50% of entire season’s rainfall. Scientists from the Intergovernmental Panel on Climate Change have warned against the changing variability in rainfalls.

No, because the municipal corporation plays a critical role in the decision making of a city’s master plan and directing its growth, with the support of urban planners. Urban planning intends to make a city function efficiently, by marking layouts and zones in a city, designing networks of mobility, water supply, electricity, sanitation and drainage.

Sometimes the focus of making efficient cities overshadows conserving its natural resources. To accommodate a growing city’s population or cater to real estate greed the natural repositories are converted into buildings, roads or transport systems. Most citizens, having lived some years in any city might be witness to such transitions in their city.

So, these climate events superimpose on bad urban planning which has slowly engulfed environmental resources while building more and more.

Commuters wade through waist-deep water during a heavy downpour in Mumbai on August 4. Photo credit: Indranil Mukherjee/AFP

What can be done?

We give five ways in which we can avoid the situation and also protect the marginalised population who get affected by these, years after years.

Environmental planning

It is important to plan for a city’s growth in a holistic manner with adequate inclusion of natural open spaces such as parks, forests, lakes, streams, rivers, wetlands and scrublands. The development plans for a city prepared by urban planners and the city’s local authorities often follow a top-down approach.

Protecting blue and green infra

The capacity of a city to deal with floods depends highly on the health of its water bodies, forested lands, and green cover. These are called natural sponges as they help to absorb excess surface runoff, recharge groundwater and reduce the impacts of floods. Protecting and preserving their natural edges and minimising impervious interventions on or around them is critical for their upkeep.

A city’s blue and green infrastructure also improves the city’s health by groundwater recharge, improving water quality, air quality, maintaining suitable microclimate and attenuating flood impacts.

Maintaining drainage system

A catchment has natural drains that connect to streams and rivers which play an important role in draining excess surface runoff.

In coordination with the irrigation and drainage departments, these drains should be mapped, maintained and monitored in a similar way that is done for rivers. Filling and construction over the natural drains should be prohibited, and dredging of old drains should be done. Similarly, before monsoon, the piped drainage network of the city should be cleaned, maintained and repaired where needed. An assessment of under-designed drainage pipes should be made, and appropriately rectified.

Climate-resilient planning

The meteorological department provides rainfall data and forecasts, while the Central Water Commission could provide data on discharge rates in rivers. Such data helps in gaging possible scenarios on the ground, predicting the possibility of flood and early evacuation is possible in vulnerable areas. Yet there is more uncertainty with changing rainfall patterns and changes in urban built form.

Real-time modelling techniques, predicting scenarios, collaborating with research institutes, sharing data of live flood hotspots with citizens are some ways that the local authorities can use data and predictions to plan effectively.

Protecting the poor and marginalised

One of the first sets of people to be affected by floods in the city are the poor and marginalised. Slum settlements often lack adequate drinking water supply, sanitation and drainage facilities.

A prior mapping of temporary shelters in flood-vulnerable areas and a database of those living in them could help in making relief reach faster. Providing relief in terms of safe and hygienic shelter, clean drinking water, food and medical aid should be a priority for local governing authorities. A long-term but important focus of the authorities should be on providing proper housing with sanitation and drainage facilities.

Dr Anjal Prakash is the Research Director and Adjunct Associate Professor, Bharti Institute of Public Policy, Indian School of Business in Hyderabad. He is IPCC’s Lead Author in the chapter on Cities, Settlements and Key Infrastructure in Assessment Report 6.

Aishani Goswami is an independent architect and water professional. She did her B Arch at CEPT University and M Tech in Water Resources Engineering and Management at TERI School Of Advanced Studies.