The depleting water bodies because of the encroachment over them is severely affecting the ecology of the city. The consequent result of this is that Chennai faces drought during less rainfall whereas water logging and floods during heavy rains.
The city is suffering from severe water shortage this year due to the 60% deficit in the north eastern monsoon. It had already experienced one of the most devastating floods in 2015. These natural disasters have an alarming indication of the diminishing water bodies in Chennai. The city once had around 650 lakes and rivers which were a source of their freshwater. Besides this they were also responsible for recharging the ground water level thus preventing drought. During heavy rainfall these rivers regulated the flow of water to human settlements by draining the excess water.
However with the rapid growth of urbanization and industrialization most of these water bodies have lost their existence. Ever increasing population in the city has led to the increasing demands for housing societies, institutions and industries. Most of this construction has taken place over these water bodies. Also the direct discharge of industrial and municipal waste has worsened the remaining waterways.
Konnur Lake once occupied over 250 acres of land. Due to the residential and industrial construction it has now been reduced to 20 acres. Over 4000 houses have been built over it and it also supports the Sidco Industries. While the remaining 20 acres has also been allotted for institutional construction. Sidco Nagar was one of the worst affected areas during the 2015 floods. The construction over the lake restricted the free flow of water into the lake which had a devastating effect over the nearby slum dwellers.
The urban planning authorities do not take into consideration the ecological balance of the city while devising any architectural plan. This way they affect the natural penetration process which further leads to floods during heavy rainfall while drought in case of less rainfall. Besides this the lakes and rivers which are not considered fit for drinking or irrigation are declared as wasteland permitting construction over it. This again disrupts the ecological balance of the city. Even though Chennai receives an average rainfall of 129 cm, encroachment lets only 5% of this water to percolate into the ground. Moreover over 80% of the groundwater has already been exploited. Further extraction from the ground could lead to salt water ingression.
Pallavaram Lake which once spread over 200 acres is now left with just 50 acres. The lake was bifurcated after the construction of Thoraipakkam road for connecting Chennai Airport and Rajiv Gandhi Salai. One side of the lake still remains however the other side has choked to death due to Encroachment and dumping of effluents from nearby leather factory, industries and sewage waste. This part of lake has become a dump yard due to the consistent dumping of garbage for the past few decades. This dumping has contaminated the ground water of that area.