admin123 - 20 September, 2007 | Bangalore | Infrastructure | lakes | Planning

Being among the largest wetlands of Bangalore, the health of Bellandur lake is symptomatic of the condition of the waterbodies all across the city.

A recent study by the Energy & Wetlands Research Group at IISc points out that rampant unplanned developmental activities, untreated sewage, solid waste disposal, and encroachment of lake beds in its catchment have put the Bellandur Lake under extreme environmental stress, impairing the functional ability of the lake's ecosystem resulting in poor water quality, depletion and contamination of ground water, and frequent flooding in the catchment. Lack of integrated planning approaches pose serious threats to the sustainability of the region.

Here are some excerpts from their report: Environmental Impact of Developmental Activities
in the Bellandur Lake Catchment. Authors: Dr. T.V. Ramachandra, H.S. Sudhira, B. Karthick, and K.G. Avinash, Energy & Wetlands Research Group, Centre for Ecological Sciences, IISc

Bellandur Catchment Area
The Bellandur lake catchment area falls into almost 41 wards of the Bangalore Mahanagara Palike. Bellandur Lake has to bear the natural drainage that flows into the lake from all these wards including both storm water and sewerage water.

The over all catchment area is about 287.33 sq. km with a water spread area of 361 ha. The terrain of the region is relatively flat and sloping towards south of Bangalore city.

Three main streams join the tank, which form the entire watershed. One of the streams originates at the northern part of the region, Jayamahal and covers the eastern portion and is referred to as the eastern stream. Another stream originates from the central part of the city, Krishna Raja Market and covers the central part of the region before joining the tank and is called the central stream. Another stream commands southwestern part of the region called the western stream. Further, before the confluence with Bellandur Tank, all the streams come across two to three tanks. Belandur lake itself drains into the Varthur lake which ultimately joins the Pennar river,

The rainfall data is available for the last 100 to 110 years. Rainfall varies from 725.5 mm to 844.8 mm. The district receives 51 % of the total annual rainfall in the southwest monsoon period, i.e. June to September.

The population in the lake catchment under the municipal limits is about 1721779 persons as per the 2001 census. This is almost one-third of the Bangalore city’s population for which the lake catchment is catering to. With the natural topography of the catchment sloping towards the lake in the entire catchment, any storm water run off eventually makes its way into the lake. Further, with the increased presence of urban areas in the catchment, the lake is also receiving wastewater generated in these areas that flow along the natural drainage.

Land Use Changes in the Catchment
The land use changes in the catchment have been studied using a combination of the satellite remote sensing data and field investigations. In the 1973 data, the network of tanks was well connected with each other the vegetation (seen in red) prevailed along the drainage linking these tanks. By 1992, with urban sprawl extending outwards, these are seen to diminish. However, in the recent data of 2000, the entire catchment is almost succumbed to urban sprawl. This is evident from the disappearance of the water bodies, vegetation across the drainage and the drainage itself.

It can also be seen that the urban sprawl has now extended up to the south west of the Bellandur Lake especially in the region in and around Madiwala, Koramangala and Ejipura. Apparently, these wards, Madiwala, Koramangala and Ejipura are also the hub of immense activity for the software industry and thus have been a centre for attracting growth.

At this juncture, with the loss of green spaces and effective drainage in the region, any amount of further development can be disastrous. Subsequently, with the alteration of topography especially in the lakebed by residential or commercial layout developers has affected the integrity of watershed and has severely affected the natural course of the storm water runoff. This can cause flooding in times of heavy downpour as evinced from the recent deluges in parts of Bangalore (Bannerghatta Road and JP Nagar) and Mumbai.

It is thus imperative of the planning and administration to take adequate precautions from preventing any such large scale topography alterations in the catchment. Government should initiate action to penalise the individuals and agencies responsible in the heinous crime of topography alterations with immediate effect.

To be concluded ...

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