Cities are both drivers and hotspots vulnerable to climate change
Cities are central to India’s economic growth. By 2030 they will generate 70 percent of net new jobs, and produce more than 70 percent of GDP.
But 70 percent of cities are already vulnerable to climate change. On one hand, the potential financial damage from extreme events, heat, and drought will be staggering. The urban poor in particular will bear much of the burden.
On the other hand, cities also hold the key to altering this trajectory. Because so much of the new development (much of it greenfield) will occur in and around existing urban areas, how we imagine and plan cities will be crucial to determining the future of our planet.
Cities are already experiencing the negative effects of climate change
In urban India, there are 3 main ways climate change is negatively impacting the landscape:
Droughts: According to a recent report by the NITI Ayog 21 major cities are expected to run out of groundwater as soon as 2020, affecting around a 100 million people. A 2012 study by the IISc revealed that for Bangalore, domestic water use alone results in an estimated groundwater overdraft of 130%.
Extreme Heat: The peak temperature differences between a city and its surrounding rural area can be as much as 6°C. A recent study conducted by IIT-KGP found that the Surface Urban Heat Island Intensity (SUHII) for 44 major Indian cities was on average upto up to 2°C higher than surrounding rural areas.
Flooding: Urban India has seen an increase in flood peaks by 2-8 times and flood volumes of up to 6 times. Additionally the time taken to reach the flood peak has reduced leading to excessive economic losses in the form of damage to property and loss of productivity. The four most populous cities in India have witnessed at least three or more instances of serious flood damage in the past decade.
One effective way of improving climate resilience in cities is through reimagining water and wastewater infrastructure
Climate resilience can be enhanced by creating an economic case for wastewater and a blue + green infrastructure plan.
Droughts: According to the CGWB around 40% of Bangalore depends on groundwater, and this number almost doubles in the outskirts of the city where most new development is happening. By creating a blue-green infrastructure plan, the city can be designed to allow up to 13.5% of rainfall to permeate to the groundwater tables. Additionally, by creating an economic case for wastewater reuse, we can substitute up to 40% of existing freshwater supplies with wastewater, thereby increasing freshwater resources.
Extreme Heat: Through the creation of a blue-green infrastructure plan, Bangalore’s extremes in heat can be combated by increasing tree and green cover, roof gardens and shading building facades. In shaded areas the temperature can drop almost 6-7°C degrees, and in areas with rooftop green spaces, the internal temperature can drop by as much as 2-3°C degrees.
Flooding: The main causes for urban flooding in Indian cities is a combination of development in low lying areas like dried lake beds, lack of permeable surfaces to capture rainwater as well as undersized and clogged stormwater infrastructure leading into sewage filled lakes. Bangalore previously relied on a cascading lake system for its stormwater management. However with a breakdown of the linkages from one lake to another and the presence of excess sewage in the surviving lakes, this system fails to retain stormwater leading to overflow and floods. In a field survey conducted by IISc in Bangalore in 2007 it was found that almost 54% of lakes were encroached by illegal buildings. Such locations routinely flood as stormwater drains into these low-lying areas. Of the remaining lakes nearly 66% of lakes are sewage fed, 14% surrounded by slums and 72% showed loss of catchment area reducing their ability to buffer from flooding. By creating an economic case for wastewater, and making wastewater a commodity, the amount of sewage ending up in lakes and stormwater channels can be drastically reduced. Additionally, identifying green cover and open spaces which can be used to capture rainwater as well as act as retention pools in the event of floods can help minimize damage.
Accomplishing this requires a systemic and partner-driven approach to implementation
Although there are already many players in this ecosystem working on pieces of the problem, they are primarily working in silos. There are underlying structural reasons why this is happening:
-Absence of information on areas outside their expertise – guidelines, primers
-Absence of a plan that everyone can work of
-Absence of a platform/ coordinating mechanisms connecting actors
We are proposing to bring together the partner ecosystem to work together to create the economic case for wastewater as well as creating a blue-green infrastructure plan.