650 to only 27 currently. The Chennai River Restoration trust set up by the government is working on the restoration of Adyar river. Environmentalist Foundation of India is a volunteering group working towards wildlife conservation and habitat restoration. The encroachment of urban development on wetlands has gravely hampered the city's sustainability, and contributed both to the city's floods in 2015 and water scarcity crisis in 2019. Climate Chennai has a dry-summer tropical wet and dry climate under the (Köppen climate classification). The city lies on the thermal equator and is also on the coast, which prevents extreme variation in seasonal temperature. The hottest part of the year is late May to early June, known regionally as Agni Nakshatram ("fire star") or as Kathiri Veyyil, with maximum temperatures around . The coolest part of the year is January, with minimum temperatures around . The lowest recorded temperature was on 11 December 1895 and 29 January 1905. The highest recorded temperature was on 31 May 2003. The average annual rainfall is about . The city gets most of its seasonal rainfall from the north–east monsoon winds, from mid–October to mid–December. Cyclones in the Bay of Bengal sometimes hit the city. The highest annual rainfall recorded is in 2005. Prevailing winds in Chennai are usually southwesterly between April and October and north-easterly during the rest of the year. Historically, Chennai has relied on the annual rains of the monsoon season to replenish water reservoirs, as no major rivers flow through the area. Chennai has a water table at 2 metres for 60 percent of the year. The city of Chennai is located on the east coast of India, which is also known as the Coromandel Coast. Chennai is largely dependent on NE monsoon, since 65% of rains are received in this season. Cyclones and depressions are common features during the season. Cyclones, in particular, are especially unpredictable. They may even move towards Orissa, west Bengal, Bangladesh, and also Myanmar. The season between October and December is referred as the NE monsoon period. Floods are common during this period. In 2015, Chennai received record-breaking rains since 1918, which caused massive floods. Land usage As of 2018, the city had a green cover of 14.9 percent, against the World Health Organization recommendation of 9 square metres of green cover per capita in cities. The city had a built-up area of 71 percent. Waterbodies cover an