Flooding is experienced in cities due to anthropocentric actions, and are now exacerbated by Climate change. The following maps can be used to see this issue in context of several Indian cities - Bengaluru, Delhi, Chennai, Mumbai, Aurangabad, Nasik, Mandi and Hyderabad. The first 4 cities are discussed below the key map which can be used to view historical maps against present day flooding areas.

1936 Map of Bengaluru (Bangalore)

Bengaluru is situated on the Deccan plateau which is at an elevation of about 3000 feet. As seen from the overlay of 1935 map, the city had several natural and constructed lakes which were interconnected. During heavy rainfall these lakes received and stored water and were traditionally a source of water for the city. However, during the colonial rule, a system of piped water supply was introduced in Bengaluru along with many other Indian cities. . This led to the neglect of waterbodies and these were gradually filled up and reclaimed. Several lakes have simply been erased and large developments have come in their place. This prevents rain water percolation into the ground thus preventing recharging of ground water reserves. On the other hand, the excess water then causes flooding. The city has faced flooding recently and is also grappling with acute water shortage due to receding ground water levels. The Cholghatta Tank getting converted to a golf course is just one example out of many such tanks which eventually succumbed.

1857 and 1929 Maps of Delhi

Delhi has two prominent geographical features, the Ridge and the Yamuna flood plains. Rainwater naturally drains from the hills and meets the Yamuna. This is seen from the 1857 overlay map indicating the presence of several east-west ravines. Ravines are deep gorges with steep banks, which can take in considerable amount of water during floods. However it is seen that the city is built over these ravines, which could have probably taken in the excess flood waters from Yamuna during the recent floods. The city’s ability to being resilient to flooding due to extreme rain can be understood through its approach towards urbanization. Negating existing soft natural systems will only bring in adverse impacts.
There is an opacity slider below the map to make the map transparent and one can switch the map on or off from the legend on the right.

1934 Map of Chennai (Madras)

Chennai is located on eastern coastal plains and experienced unprecedented floods in 2023 due to reasons similar to Bengaluru. As seen from the overlay map of 1834, at least 7 major water retaining structures have been lost to dense urbanisation. Instead of relying on the existing local and decentralised sources of water, piped water brought in a disregard to the existing water holding tanks. The old map shows that the tanks were surrounded by plantation areas which must have been fed by canals from these tanks. However urbanization brings in a change of land use thereby reducing the dependence on water from the tanks. The hardened urban landscape which was soft once upon a time, is no more able to percolate and hold water. Climate change has multiplied the impact of extreme events of flooding several times, since the frequency of cyclones has increased, which bring in heavy rains over a short period of time as in Cyclone Michaung in Chennai in 2023.

1926 Map of Mumbai (Bombay)

Mumbai is bordered by the Arabian sea to its west and the hills of Sanjay Gandhi National Park to the north east side which are responsible for draining the rainwater towards the sea. However, during extreme rainfall events, which are more frequent now, flooding is experienced at the red circles, which are chronic flooding areas as per the Fact Finding Committee of 2005. The overlay of the 1926 map of Mumbai shows the marshy areas in several areas that were gradually reclaimed because of the town planning schemes of 1960s, site and services of 1980s and rapid private real estate developments that began in the1990s and are ongoing.