Since 2001, Bangalore has seen its population almost double.
That unprecedented growth has strained the water resources of what is known as the Silicon Valley of India. About 40% of Bangalore households pump water directly from the groundwater aquifer, through hundreds of thousands of borewells.
But until recently, Bangalore – officially known as Bengaluru – didn’t know the sustainability or status of its groundwater aquifer. Monitoring was sparse and infrequent, providing little detail on how water levels react to increased use, extreme weather and a changing climate.
SEI is working to change that through a joint project with the Indian Institute of Management-Bangalore’s Centre for Public Policy and the Indian Institute of Science. The Bangalore Urban Metabolism Project (BUMP) aims to develop a model that treats cities like living entities, using data to help solve the urban sustainability conundrum.
Water is a big part of the puzzle in Bangalore. With more than 10 million residents, every drop counts; effective management requires detailed data on supply and demand, both today and in the future.
“If you want to manage a system, you have to understand its components, and how they relate to each other. You have to be able to quantify them,” said SEI Senior Scientist Vishal Mehta. “Water is one of the most difficult Indian urban challenges.”
But BUMP has made significant progress. For almost two years, researchers have measured water levels every month at 154 locations throughout the city. The result: a treasure trove of data that will help scientists and policy-makers understand groundwater behavior for the first time in a major Indian city.
Between December 2015 and June 2017, most wells saw a decrease in water levels, thanks to a two-year drought. However, researchers found that extreme rainfall can substantially recharge groundwater; in August and September 2017, during the highest rainfall in 100 years, every one of the 154 monitored wells showed sharp increases in groundwater levels.
Such data is important in evidence-based policy-making, Mehta said. The project’s findings, for example, disproved earlier news reports that the 2017 rainfall had not replenished the groundwater.
Researchers also found that water levels appear to be higher (shallow) in the central, higher parts of the city, while they are lower (deeper) in the outer, lower-lying areas. This is unusual; typically the opposite is true.
In Bangalore, however, the higher parts of the city are better connected to water supply pipelines and thus pump less water. The outer areas – which are fast growing – rely more on groundwater.
“These measurements are helping us understand the groundwater budget of the city,” Mehta said. “We are now looking at the human influences of pumping and leaking wastewater systems, as well as the natural rainfall recharge contributions. These findings will help guide better management in the future – and perhaps encourage other cities to monitor groundwater through dense measurements.”
This work was supported by The Cities Alliance Catalytic Fund, SEI’s Urban Initiative and the Swedish International Development Cooperation Agency (SIDA).