Why is Bengaluru running out of water?

Last month, a BBC report listed 11 world cities that were “most likely to run out of drinking water”, and put Bengaluru at number 2, behind only São Paulo, Brazil.

The report mentioned the acute shortage of water in Cape Town in South Africa, where people are now being rationed 50 litres daily, and which many fear could become the first major city to run dry in the modern era.

Other cities on the list of the most vulnerable were Beijing, Cairo, Jakarta, Moscow, Istanbul, Mexico City, London, Tokyo and Miami.

 

The report noted that more than half of Bengaluru’s drinking water is wasted due to “antiquated plumbing”, 85% of the city’s lakes “had water that could only be used for irrigation and industrial cooling”, and “not a single lake had suitable water for drinking or bathing”.

The Bangalore Water Supply and Sewerage Board (BWSSB) — the state agency managing water supply and sewage disposal — was quick to respond. It suggested that the report was alarmist, was based on old data, and was “far from the factual situation”.

 

The topographic setting of the city has radial slopes towards east and west with a smooth ridge running north to south; rainfall over the ridge area gets divided and flows east or west into the three gentle slopes and valleys of Koramangala–Challagatta, Hebbal and Vrishabavathi. Doddabettahalli 1,062 m (3,484.3 ft) is the highest point on this ridge.

This naturally undulating terrain of hills and valleys lends itself perfectly to the development of lakes that can capture and store rainwater. Small streams are formed by each valley starting with the ridge at the top. A series of shallow tanks varying in size are developed. The gentle topography has also a good potential of groundwater development.

Bangalore, with an annual rainfall of 900 mm (3.0 ft) with three different rainy seasons covering nine months of the year. June to October is the rainy season accounting for 64% of the total annual rainfall in the S-W monsoon period and 324 mm (1.1 ft)during the N–E monsoons (November – December.).

It has a salubrious climate with an annual mean temperature of 24 °C (75.2 °F) with extremes ranging from 37 °C (98.6 °F) to 15 °C (59.0 °F). The streams between ridges and valleys have been dammed at suitable locations creating a cascade of reservoirs in each of the three valley systems.

Each lake stores rainwater from its catchments with excess flows spilling downstream into the next lake in the cascade. The stormwater runs off through drains only. These drains often carry sewage in it, which results in the lakes getting polluted. Many lakes have reportedly sprung at the bottom of the lakes, some of which are stated to be choked due to silt, which also feeds the lakes. It is sad that such a beautiful city, blessed by nature has been destroyed so much.

 

Former additional chief secretary IAS officer V Balasubramanian had pointed out the overexploitation of groundwater resources and warned that there will be a major crisis by 2025 and people may have to be evacuated. A recent IISc research by a five-member team led by scientist TV Ramachandra said Bengaluru’s water crisis was a result of mismanagement of resources by policymakers.

The study stated Bengaluru gets enough rainfall to quench its thirst, but the problem was with harvesting the rainwater.

 

Another disturbing fact was on lakes. “Bengaluru’s lakes had a storage capacity of 35 tmcft of water in 1800 and the lakes had been interlinked in such a way that water was available throughout the year. Now, a majority of the lakes have disappeared and the current storage capacity is less than 2 tmcft of water, while the city’s current monthly requirement itself is 1.5 tmcft,” found the above-quoted IISc research. One tmc ft of water is equal to 2,816 crore litres and it can cater to the needs of six lakh people per year.

It is disgusting to see leaky water supply pipes unattended for days on end. When people in the slums are not supplied even drinking water free of cost, it is atrocious to see people in higher classes filling their sumps and tanks from the public taps in front of their houses through long hose pipes.

 

The importance of urban greenery to check air and noise pollution, improve groundwater resource, bring down the heat in the atmosphere and maintain bio-diversity is being highlighted time and again but the planners seem to totally ignore this point. Individuals do not need trees inside their compounds, outside their compounds on the roadsides, around malls and shopping complexes or parks.

They get carried away by neat ornamental gardens, little realizing the damage that such gardens do to the ecology. Instead, a balanced mix of flowering shrubs and fruit yielding trees, medicinal plants and trees and ornamental climbers and creepers would do more good to the city.

Water scarcity is a serious problem and one that will lead to so many other problems like unhygienic living conditions, an outbreak of epidemics, crime due to fights for water, etc. Let us all awake and start doing our best to save every drop of water.