If you have maxed out your credit card, you may be scrambling to pay your outstanding bills. India’s technology hub, Bengaluru, with its dying lakes and mushrooming urbanisation, is facing a similar situation – it has overexploited its groundwater and is now struggling to keep up with the demand, according to an expert.
“We are using groundwater like an overdrawn credit card and we don’t have the capacity to repay,” said Samrat Basak of World Resources Institute India, or WRI India, expanding on an analysis by the global research organisation.
The WRI India analysis notes that “groundwater stress in and around Bengaluru is critically high as the groundwater aquifers are overexploited”.
“In the absence of water-prudent urban development, the future growth of Bengaluru will lead to significant stress on the already overexploited groundwater situation,” Basak said, quoting the data.
The semi-arid city has been in the news for its water woes and projections that talk about the impending “Day Zero” crisis, a Cape Town like situation when taps could run dry.
.jpg "'The future growth of Bengaluru will lead to significant stress on the already overexploited groundwater situation'. Photo credit: Wikimedia Commons")
The WRI India analysis supports the call for a paradigm shift from linear centralised model to circular decentralised model of water supply and strict implementation of aquifer recharge effort.
The maps and data analysis indicate that if the “current water supply-demand practices do not improve significantly”, it will be “just a matter of time” before Bengaluru, or parts of it, are forced into a Day Zero like situation.
“Considering any future climatic stress scenarios [deficient rainfall events], there is high probability that both surface water and groundwater sources of Bengaluru come under stressed situation during a same time or similar time period,” the analysis suggests.
Moving towards a circular decentralised model of water supply – which involves reusing treated wastewater, rejuvenating urban wetlands like lakes using storm water (and not wastewater or sewer water) and adopting aquifer recharge – is critical for addressing the water security of what was once a “city of thousand lakes”.
“The idea is to have an optimised mix of harnessing surface water from river and rejuvenated urban wetlands along with groundwater and treated wastewater of lakes,” Basak said.
Major loss of tree cover, multiple deficient rainfall events, doubling of population and built-up area at the expense of open areas in the last 25 years, are some of factors that have pushed the city on edge of a water crisis, according to maps and data analysis generated by the WRI India as part of its ongoing research project, “City Water Assessment Tool”.
“There should be a balance between how you use water in stress and non-stress period,” Basak explained. “During non-stress period, if we don’t use the surface water it just flows down to the oceans. During that period, instead we can keep groundwater as a hedge and use the surface water.”
During summer when taps run dry, the demand for water tankers skyrockets.
The total water demand, domestic and non-domestic, is slated to double from 1900 million litres per day (to around 3800 million litres per day between 2018 and 2031 as the population doubles, as per the analysis.
“Under a business as usual scenario, the groundwater abstraction will increase from around 1,000 MLD today to around 1,600 to 1,800 MLD in 2031,” Basak said. “As the city groundwater is already in overexploited stage, it may not be hydrologically feasible and sustainable to meet any such increase in groundwater demand.”
Even though the city primarily relies on the Cauvery river about a 100 km away, experts not associated with the analysis advocated nurturing resources within the city.
“It could potentially mean that we have a secondary dependable water source to bank upon, something Bengaluru doesn’t currently possess,” said Hita Unnikrishnan, a researcher at the University of Sheffield who focuses on histories of urban water commons within Bengaluru.
Urban planning, especially in the context of Bengaluru, should take into account the geophysical characteristics of the landscape, rather than relying on techno fixes that are expensive, yet do not provide a promise of water security, Unnikrishnan said.
Rainwater harvesting locally through rejuvenated lakes would be the most appropriate decentralised option of meeting water demand, according to the Indian Institute of Science researcher TV Ramachandra.
“Another vital function would be groundwater recharge, which will accelerate with removal of accumulated silt and sediment, and also non-contamination of groundwater,” Ramachandra said. “This idea will materialise only if we have sensible and responsible citizens and decision makers.”
Lessons from the past
The city, founded in the 16th century, was planned bearing in mind its topography, tapping into natural depressions and an undulating terrain to create a series of networked water reservoirs that harnessed rainwater. This also prevented problems such as flooding, Unnikrishnan said.
The lakes not only provided water to the city up until about 1895, they also performed other functions, ecological as well as social. “Ecologically, they are microclimate regulators, urban biodiversity hotspots and enablers of groundwater recharge among others,” Unnikrishnan said. “They are also important for their aesthetic and recreational appeal within the humdrum of the city. They are important livelihood and subsistence providing resources to urban poor.”
As the city expanded, it witnessed a shift in dependence from local to distant sources of water, catalysed by technological interventions and centralised piped water supply system. “While in the precolonial past, it depended upon an interconnected system of rainwater harvesting via lakes and wells, today it relies on water that is pumped from the river Cauvery over a hundred kilometres away,” noted a study co-authored by Unnikrishnan.
The major surface water intake point for Bengaluru is along the Shivanasamudra section of the Cauvery, about 100 km from Bengaluru. Water is gradually pumped up to a height of 540 metres from this intake point to meet Bengaluru’s water demand, Basak said.
“The water flow at this intake point is controlled by two upstream reservoirs, the Krishna Raja Sagar and Kabini Dam,” Basak said. “The water flow within KRS is further controlled by a combination of three further upstream water reservoirs, Harangi, Hemavathi and Yagachi.”
The watershed upstream of Bengaluru’s intake point has lost around 50 square kilometres of tree cover from 2001 to 2014, an area 1,500 times the size of the city’s Chinnaswamy cricket stadium. Loss of tree cover impacts water availability and water quality at the catchment level.
Bengaluru shifted its entire water dependency to the Cauvery following the formation of the Bangalore Water Supply and Sewerage Board in 1964 and the inception of the Cauvery Water Supply Scheme in the year 1969, the study by Unnikrishnan said.
The water board spends nearly 60% of its budget on pumping water to Bengaluru.
Swallowed up by unplanned development, interconnected water bodies have declined in number from 1,452 in 1800 CE to 194 now.
With their storage capacity of about 35 thousand million cubic feet, these water bodies not only met the city’s water needs, but also stored the excess water during high rainfall years and helped mitigate floods.
Now there are 194 water bodies in an area of 741 sq km and most of them have large deposits of silt, accumulated over last four decades because of non-management or the lack of maintenance. The carrying capacity of the lakes is five thousand million cubic feet, but because of siltation the actual capacity is just 1.2 thousand million cubic feet, according to Ramachandra. He claimed rainwater harvesting through rejuvenated lakes would meet 70% of the city’s water demand.
“Reduction in surface water bodies impacts the natural groundwater recharge process,” said Basak. “Reduction in open space means reduction in the natural groundwater recharge and freshwater flows to lakes.”
The resulting degradation and conversion of the city’s water bodies has reduced the resilience of Bengaluru to flooding and drought, especially affecting the poorest and most vulnerable of its residents, explained Unnikrishnan.
“In preserving and rejuvenating existing lakes in an inclusive and sustainable manner, one can both retain these ecological benefits, provide for aesthetic and recreational green spaces within the city, while yet providing an inclusive and just urban space that respects the needs of even the most marginalised communities,” Unnikrishnan said.
According to data quoted in the study, only 72, 000 properties in Bengaluru have implemented rainwater harvesting after the Bangalore Water Supply and Sewerage Board made it compulsory in 2011. “Even if RWH is implemented, the operation and maintenance of these structures and therefore the effectiveness of these structures is questionable,” Basak said.
Amid the despair, however, community involvement in restoration of water bodies has held out hope.
Citing the examples of Jakkur and Kaikondrahalli lake restoration attempts, Unnikrishnan underscored the importance of community engagement but also stressed on “working together with local nodal agencies who are in charge of lake maintenance, as well as other aspects of lake health such as sewage treatment, sewage inflow, encroachments”.
She added, “I would say that citizen engagement is required both at the level of restoring and rejuvenating the resource as well as networking with nodal agencies to form a sustained, long-term relationship.”
This article first appeared on Mongabay.