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.
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.