Behind the Bengaluru crisis: Geography and unchecked growth | Bengaluru - Hindustan Times
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Behind the Bengaluru crisis: Geography and unchecked growth

ByRaj Bhagat Palanichamy
Sep 08, 2022 12:01 PM IST

Over Bengaluru's geologic history, the rainfall in the region created numerous seasonal streams that eroded Bengaluru’s plateau landscape resulting in the numerous valleys which act as conduits carrying water to the major rivers

Bengaluru has been facing one of the worst flood and water stagnation issues this year after a series of heavy rainfall events. The floods have serious direct and indirect impacts on human lives and the economy of the city. Some of the most severely affected areas this time around were in the eastern side of the city which houses several IT companies. To better understand the causes of urban flooding, we need to delve deeper into the geography of the city, its spatial growth, and its water resources.

People commute in a tractor trolley as firemen stand next to pumps that are used to remove water from a water-logged neighbourhood following torrential rains in Bengaluru. (REUTERS) PREMIUM
People commute in a tractor trolley as firemen stand next to pumps that are used to remove water from a water-logged neighbourhood following torrential rains in Bengaluru. (REUTERS)

Bengaluru is located at the top of a ridge which is the water divide between the watersheds of the Kaveri and the Ponnaiyar (Dakshina Pinakini) rivers. Over its geologic history, the rainfall in the region created numerous seasonal streams that eroded Bengaluru’s plateau landscape resulting in the numerous valleys which act as conduits carrying water to the major rivers.

The modern municipal corporation boundary covers the old town of Bengaluru, around Fort and Pete areas, as well as numerous villages. These older settlements, which are smaller in size were concentrated on the ridges while the valleys were used for agricultural purposes. To irrigate these agricultural lands, bunds were erected across the valleys to retain the water — creating lakes. The older streams that once flowed were redesigned to create artificial canals (kaluve) which were used for irrigation and for carrying excess water downstream.

A good chunk of the construction in lake beds (which are part of these valleys) was done by the government for different purposes — such as colleges, stadiums, bus stands etc. (HT Illustration)
A good chunk of the construction in lake beds (which are part of these valleys) was done by the government for different purposes — such as colleges, stadiums, bus stands etc. (HT Illustration)

The city’s population stood at 1.6 lakh in 1901 and grew to 84.4 lakhs (8.44 million) in 2011, and is currently estimated to be more than 10 million. This rapid and extreme growth, triggered by the conducive weather and the IT boom, created a massive market requirement for land and the city began sprawling out from the centre. Even though many planned layouts were created, most of the growth happened in an unplanned fashion. Construction activity started in the valleys and ridges; the topography of the land was ignored and eventually completely forgotten. While rampant construction activity and concretisation of surfaces reduced water infiltration into the soil, new structures started obstructing the movement of water in these valleys. Though there are isolated cases of stagnation, largely due to the engineering of roadside storm water drains in ridges, most of the flooding and stagnation in Bengaluru happens because of the obstructions in the valleys.

A good chunk of the construction in lake beds (which are part of these valleys) was done by the government for different purposes — such as colleges, stadiums, bus stands etc. The private constructions along valleys were not necessarily illegal. Many of them were legal and some of them were legalized over time — a process which often impacts vulnerable marginalized communities. It should also be noted that legal constructions do not imply ‘flood-proof’ because the valleys were not a protected landscape and construction permissions could be obtained legally. Water does not care about the legality of a constructed structure, and it flows where it can. If we look at the master plan of 2015, you can spot small, fixed buffers in these valleys. The entire valleys did not get recognized as eco-sensitive areas. Not all the kaluves and streams were in public ownership, and several minor ones were owned privately. When construction started, these began disappearing further reducing the capacity of water that can be carried from these places. Construction in valleys, the capacity and number of previously present drains and roads without large culverts to carry water from one side to the other meant that these places faced flooded. This is what is happening in several parts of Bengaluru right now.

Let us take a look at two cases — RMZ EcoSpace in Outer Ring Road and Rainbow Drive in Sarjapur Road. Flooding in these spots have been happening for years now. The topography has been significantly altered by construction activity and drains and culverts are proving insufficient resulting in water stagnation. The topography and the construction activity in these valleys and their flood plains are shown below.

The path ahead

We need to create open access highly granular datasets on topography, flood risk, and stormwater drains. This would help public and experts to better understand the situation and provide insights and solutions to the government.

The master plans for the city should consider protecting the valleys as the city grows. A detailed flood hazard and zonation map needs to be created with extreme rainfall and return periods taken into account. This should be integrated into the planning process and land use in high hazard zones should be restricted. Land pooling schemes can be explored so that the economic aspirations of people who own land in valleys are not affected.

Apart from a spatial land use regulation master plan, the city needs to have a plan for storm water drainage that employs scientific methodology rather than arbitrary methods. Since most of Bengaluru’s original canals and streams do not exist anymore, we need to create more drains and culverts based on the overall storm water plan for the city. Streets and roads should not be designed in an isolated manner. In case a street needs to be redesigned as a flood mitigation measure, it has to be done in a holistic manner taking into consideration pedestrian requirements, water infiltration needs, utilities, vegetation and other aspects that can help in improving the livability around them.

Cities should be self-governing units with citizens playing a greater role. Unfortunately, there is a huge disconnect between citizens and the government and there is also disconnect between different parastatals, arms and levels of the government itself. Recommendations from previous reports such as the BBMP-Restructuring Committee report should be revisited.

We must look at addressing these long-term issues, on how we govern and finance ourselves as a city unit, to arrive at solutions that can lead to safer and more resilient cities.

(Raj Bhagat Palanichamy, GeoAnalytics – Sustainable Cities, WRI India. All views expressed by the author are personal)

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