Urbanisation and Lakes of Bengaluru

Bengaluru is India's fifth-largest urban centre, with a population of 8.5 million people (census 2011). Within a 0.64 per cent land share, Bengaluru is a place of residence for 14.64 per cent of the state's population. The population of the city increased at the highest rate in urban India—42 per cent—between 2001 and 2011. The decadal population of Bengaluru is depicted in this Figure 1. Moreover, it is distinguished by a radial system made up of the axes that converge in the city's centre. Figure 2 depicts Bengaluru's spatial expansion between 1973 and 2010 which shows how significantly the spatial distribution of built-up areas and vegetation has altered since that time. 

  

Bengaluru is appropriately referred to as "The Garden City of India" and "The City of Lakes" due to its diverse biological resources. Here, forests make up 4% of land use (16.89 sq km), lakes make up 9.25% of land use (36.45 sq km), and parks make up 7.5% of land usage (30. 24 sq. km). The majority is made up of lakes, which is why there are both quantitatively and qualitatively significant for a detailed analysis.

The diverse landform undulations in Bengaluru's radial drainage system assist water flow from the plateau's top to the base. The population heavily relied on rains and groundwater because there were no other close perennial supplies of water. To meet a sizable portion of their water needs, they dug out lakes and tanks in these depressions. Bengaluru is divided into five primary catchments (Hebbal, Bellandur, Vrushabahavthi, Arkabhavati and the other one) by the main North-South ridge and the cross East-West ridge, and these lakes were connected when they were carved out in response to the flow of water.

The Present Situation of the Lakes

A team of researchers from the IISc Bangalore led by Professor Ramachandra recently did a study on lakes titled "Wetlands: Treasures of Bangalore (Abused, Polluted, Encroached and Vanishing)" that examined 105 lakes in the area. Only four lakes seemed to be in a good condition, but 25 lakes were discovered to be in very bad condition, completely covered with macrophytes or dumped with solid or liquid wastes, with little to no water.

It was found that 90% of the lakes were sewage-fed due to sustained flow of untreated sewage and industrial effluents, dumping of solid wastes and building debris. Even the water quality analysis of 80 lakes found that almost half of the lakes were highly polluted and none of the lakes had water that was fit for drinking according to standards set by the Central Pollution Control Board. The lakes in the Koramangala-Challaghatta valleys were the most polluted as compared to those in the Hebbal, Vrushabahavthi valley. Also, fish deaths were reported in Sankey, Lalbagh, Jakkur and Munnekolala lakes. Whereas, foam formation was seen in lakes such as Bellandur, Rampura, Varthur etc.

Professor Ramachandra argues, "It is so sad that there are so many resources put in to change the situation, but there is no initiative and interest from the bureaucracy to make a real difference. In this study, the researchers have found that four lakes were better off than many others and why did this happen? This was only because they were restored and taken care of by residents." If local people, non-government organisations, bureaucrats, and regulators, come together and decide to bring about a difference with utmost sincerity, the situation will change, because the right to live with clean water and the environment is for everyone, not only the influential.

A few main reasons for this state of the wetlands could be a lack of sense of belonging among all the stakeholders; sincerity and poor decision-making from the bureaucracy; poor implementation of regulatory norms and governance; lack of coordination between the many para-state agencies who were custodians of the lakes leading to their poor maintenance.

Impact of Vanished and Encroached Lakes

A few of the impacts of urbanisation that we can notice on lakes can be broadly categorised as a change in the governance of lakes, change in resource use and the impact on the lake ecosystem. Here is the detailed list of visible changes on lakes that we saw:

• The decline in the number of lakes: It is a well-known fact that several lakes in the city have disappeared as a result of rapid urbanisation. Moreover, several studies have been conducted that point toward rapid urbanisation as the prime reason for the loss of wetlands.

• Loss of irrigated, watershed and catchment areas: The immediate impact of the disappearance and deterioration of lakes is the loss of irrigated areas. As per the latest data, there are around 36,000 tanks in the state with a command area of approx 7 lakh hectares, which works out to 18.82 ha of irrigated area per tank and an average water-spread area of 11 ha. If we go by this norm, the disappearance of 195 tanks in Bangalore caused the loss of irrigated area of about 2540 ha.

• Human suffering and health hazards: The loss of irrigated areas and the resultant decline in production are directly related to the conversion of lakes into non-agricultural purposes. Moreover, the contaminated water of these lakes is also causing many diseases such as Jaundice, Cholera, and other serious health hazards in the immediate environs. The percolation of this water into the ground has caused a high nitrate presence in the groundwater.

• Loss of drinking water sources: Today, the city of Bangalore is getting water from Cauvery which is 140 km away at an enormous price. According to BWSSB, the total cost of producing and supplying 2,47,382 million litres of water during 2001 was Rs 5722 million, which worked out to Rs 23.13 per litre as against Rs 5.98 in 1991. This cost per litre is exorbitant when compared to many metros in the country. Much of this has been accounted for in power cost. It is stated that the power bill comes to about Rs 21 crore per month. Moreover, the recharging capacity of lakes has also been reduced due to non-filling and loss of water-spread area and storage. This situation has forced the civic bodies to shift from tank sources to alternative sources for supplementing drinking water, though at a high cost.

• Reduction of storage due to encroachment and sedimentation: The lakes have become dumping grounds for all kinds of waste materials which has led to water pollution and silt formation in the lakes affecting the water-holding capacity of water bodies. Even, the sedimentation has also reduced the water impounding capacity of the lakes.

• Pollution of water and groundwater: High concentration of metals in the grown vegetables using polluted lake water. The pollution of lakes due to sewage, sludge and industrial effluents is a common phenomenon in urban areas. Ultimately these led to the crops growing.

• Impact on Flora and Fauna: A variety of rich fauna and flora around the lakes have contributed to the salubrious climate in the city. But, the loss of lakes and water-spread areas has affected the flora and fauna of the tanks in a significant way. The flora such as typha, Lily, etc. is rarely to be seen at present.

• Flooding of Urban Areas: The average height of Bangalore in terms of topography is 850 to 930 meters. Water flows from these heights and is harvested by a chain of tanks and has a hierarchical system to arrest rainwater in such a way that the overflow of one tank reaches into the other tank downstream without flooding and causing loss of property and life. Despite this system, devastating floods occur in the city damaging property and endangering life.

Hence, keeping in the mind the adverse situation of lakes in Bengaluru, adopting a holistic and integrated approach to conserving and managing lakes through a bottom-up approach could be a way out.

Written By: Srishty Pandey (Group 1)