Desalination is not the Solution to Southern India’s Water Stress

8 February 2017 Mervyn Piesse, Research Manager, Global Food and Water Crises Research Programme

Background

The long-running drought in southern India appears likely to continue into the early months of 2017. All 32 districts in Tamil Nadu have been declared drought-affected with annual rainfall between 35 and 80 per cent below average in 2016. Both the south-west monsoon, between July and September, and the north-east monsoon, between October and December, failed. Kerala, a state to the west of Tamil Nadu, has struggled through its most severe drought in 115 years. In Karnataka, a state to the north of Tamil Nadu, the drought is now in its third year. It is rare, but not unheard of, for both monsoon systems to fail in the south of the country. In times of drought, farmers in southern India tap into reservoirs to meet the shortfall. In some areas, however, these reserves are only expected to last for another 90 days. Preference has been given to using the remaining water for drinking, household use and industry instead of the very thirsty agricultural sector.

India States Map

Comment

Competition over water resources in southern India is likely to grow in coming years. Southern states, such as Kerala and Tamil Nadu, have embarked on industrialisation projects with mixed levels of success. These states are competing with China to become major textile producers. These ambitions are built on the relatively cheap cotton that is grown in the country, but recent years of erratic rainfall and low yields could threaten these plans.

Tamil Nadu relies on rain-fed rivers from Karnataka and Kerala for its surface water supply, but this arrangement has come under increased pressure in recent times. In September 2016, there were widespread protests as tensions rose between Karnataka and Tamil Nadu over the sharing of water from the Cauvery River. There are also fears that Kerala will withhold water from the Periyar River. Tamil Nadu has requested that Andhra Pradesh release more water from the Krishna River to service the drinking water needs of Chennai, a large city on the east coast of the state. Of the four south Indian states, Tamil Nadu is at the greatest risk of water insecurity due to its heavy reliance on the goodwill of its neighbours.

Chennai has experienced extreme water insecurity in the recent past. In 2003/04, its four reservoirs went dry and, as the city turned to groundwater reserves, these also declined. The city’s piped water supply was turned off and, apart from sporadic service, did not function for the best part of a year. During this time, the 4.5 million residents of Chennai required 600 million litres of water per day. To meet demand, water was transported from aquifers 150 kilometres from the city on trains and trucks.

As the failure of two consecutive monsoon seasons was blamed for the water shortage, the city turned to climate independent water sources. Three desalination plants have been built in Tamil Nadu since 2009, with a fourth, and possibly fifth, in the pipeline. City residents are worried about construction, maintenance and operating costs while the state’s high reliance on coal-powered electricity plants have also fuelled concerns about the effect additional desalination plants could have on Tamil Nadu.

The Minjur and Nemmeli desalination plants have operated since 2010 and 2013, respectively. Together, the two plants provide Chennai with up to 200 million litres of water per day. The third plant, commissioned in 2009, was built by the Chennai Petroleum Corporation to provide water for a local oil refinery. A new plant at Perur will have a capacity of 150 million litres per day while a fifth will be able to produce up to 400 million litres per day. If all the planned plants are built, Chennai’s desalination capacity would increase to 750 million litres per day. Unless per capita demand for water has declined since 2003/04, this will not be enough to satisfy the 8.2 million people now living in the city in times of water scarcity.

As water levels in dams diminish, the region also faces a looming electricity crisis. Water reservoirs in Tamil Nadu are reportedly 82 per cent lower than normal. Poor water management is partly responsible for the state’s dire situation. In 2015, parts of the state, mainly around Chennai, flooded. Due to poorly maintained rainwater harvesting infrastructure, much of the water, which could have been harvested and stored for later use, was lost.

Desalination plants alone will do little to strengthen Tamil Nadu’s water security. While they will improve the resilience of Chennai in times of drought, and possible serve as a model for other Indian cities to emulate, they will not resolve the problems that arise when the city floods. Neither will they be capable of producing enough water at a cheap enough price to sustain the industrialisation of the region. If the state is serious about resolving its water security challenges it will also need to focus on demand-side solutions and repair and maintain its rainwater harvesting and drainage infrastructure.

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