The coastal city of Chennai has a metropolitan population of 10.6 million as per 2019 census. As the city lacks a perennial water source, catering the water requirements of the population has remained an arduous task. On 18 June 2019, the city's reservoirs ran dry, leaving the city in severe crisis. Although three rivers flow through the metropolitan region and drain into the Bay of Bengal, Chennai has historically relied on annual monsoon rains to replenish its water reservoirs since the rivers are polluted with sewage. With the population increasing over the decades, the city has faced water supply shortages, and its ground water levels have been depleted. An earlier Veeranam Lake project aimed at augmenting the city's water supply failed. However, the New Veeranam project, which became operational in September 2004, has greatly reduced dependency on distant sources. In recent years, heavy and consistent monsoon rains and rainwater harvesting (RWH) by Chennai Metro Water at its Anna Nagar Rain Centre have significantly reduced water shortages. Moreover, newer projects like the Telugu Ganga project, which brings water from rivers such as the Krishna River in Andhra Pradesh, have eased water shortages. The city has constructed a couple of sea water desalination plants to further increase the water supply, with the two functioning since 2010 and 2013, respectively. A third one has been planned. However, Chennai is expected to face a huge deficit of 713 million litres per day (MLD) as the demand is projected at 2,248 MLD and supply estimated at only 1,535 MLD in 2026. As of 2017, the total volume of water harvested was 339 mcft and groundwater recharge was 170 mcft. The expanded Chennai Metropolitan Area (CMA) has nearly 4,100 water bodies, with a potential storage capacity of 150,000 million cubic feet.
History
Until the middle of the 19th century, Chennai city received water from shallow wells and tanks, such as the Nungambakkam tank, in the region. The first proposal to tap water from Kortalayar river situated about 160 km northwest of the city was forwarded by Fraser, a civil engineer. The ₹ 1.85-million project involved construction of a masonry weir across Kortalayar River at Tamaraipakkam and diverting the water into Cholavaram lake and further into the Red Hills Lake by means of a channel. This established the first scientifically designed water distribution system in the city. The primary works were completed in 1870, and in 1872, a valve house at Red Hills and a gravity-aided earthen supply channel to supply water were built. Within the city, water was delivered by gravity into a masonry shaft at Kilpauk, where the channel ended. From here, the cast iron mains of the city branched off to carry water to different parts of the city. According to J. W. Madeley, a pioneer of Chennai water supply and sewerage system during 1914–1918, these were considered sufficient for an anticipated population of 660,000 in 1961 at a rate of 25 gallons per head per day. However, the need for further improvement was felt in 1936. Estimates say that the expanse of water bodies in and around Chennai contracted from 12.6 square kilometers in 1893 to 3.2 square kilometers in 2017. There were about 60 large water bodies in the Chennai area at one time, but as of 2017, they have come down to just 28, most of which are small.
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