Preserving Waterbodies - Chennai Case Study

What is the issue?

Though blessed with thousands of water bodies and the annual average rainfall being reasonably good, water shortage still persists in Chennai.

What is the present situation?

• Chennai district ended with a 57 % deficit in Northeast monsoon rain in 2016.
• Chennai Metrowater is planning to tap water from new resources, abandoned quarries or agricultural wells and smaller water bodies.
• Residents are already thinking of sinking deeper borewells.
• Meteorologists note that the water scarcity is more of human-induced, as the annual rainfall has been less than 100 cm only on a few occasions since 1969.
• According to UN-Water, about 50% of the world’s population live in cities and this is bound to increase to 70% by 2050.
• The global water demand too is set to go up by 50 % in two decades.
• There is a rise in haphazard urbanisation with least importance to urban ecosystem management.

What is the problem?

• There are nearly 3,600 waterbodies in Tiruvallur, Chennai and Kancheepuram districts.
• If maintained properly, nearly 80 tmcft of water could have been stored during floods.
• The reservoirs that cater to the city have only a capacity to store 11 tmcft.
• Nearly 300 thousand million cubic feet (tmcft) of water is estimated to have drained into the sea through various waterways during 2015 floods.
• Water experts point out that could have been saved and used in times of crisis had we taken care of the waterbodies in and around Chennai and its neighbouring districts.

What should be done?

• We should understand the characteristics of mansoon and plan accordingly by preserving water bodies.
• The extreme weather resulting in floods or drought must be expected and used as an opportunity.
• Drought is the best time to desilt waterbodies.
• Waterbodies have been neglected for the past decades, leading to their systematic destruction and groundwater depletion.
• The government accelerate the project to lay a direct pipeline to transmit surplus water from Mettur dam.
• The government and residents should take a collective responsibility to arrest sewage flow into rivers.
• The building plan approvals must be provided to those large commercial buildings that show a water source to cater to the demand of residents.

What is grey water recycling?

• Greywater  or sullage is all wastewater generated in households or office buildings from streams without fecal contamination.
• Any attempt to restore the city waterways is futile, unless raw sewage flow is arrested and a comprehensive sewer network is in place.
• Though water from waterways cannot be used directly, they would be a good source of groundwater recharge.
• Chennai generates nearly 700 million litres of sewage daily. This could be recycled through decentralised treatment plants.
• It would work out cheaper at Rs 28-30 per kilo litre than the desalinated water that costs Rs 48 per kilo litre. The sludge could be converted into bio manure.

Source: The Hindu