2015 South Indian floods is a disaster happened in South India.The heavy floods were resulted due to heavy rainfall by the annual northeast monsoon in November–December 2015.The mainly affected regions are Coromandel Coast region of the South Indian states of Tamil Nadu,Andhra Pradesh, and the union territory of Puducherry and especially the most devastated area, the city of Chennai. More than 500 people were killed and over 18 lakh (1.8 million) people were displaced.
From October to December each year, a very large area of south India, including Tamil Nadu, the coastal regions of Andhra Pradesh and the union territory of Puducherry, receives up to 30 percent of its annual rainfall from the northeast monsoon (or winter monsoon). The northeast monsoon is the result of the annual gradual retreat of monsoonal rains from northeastern India.
On 8 November 2015, during the 2015 North Indian Ocean cyclone season, a low pressure area consolidated into a depression and slowly intensified into a deep depression before crossing the coast of Tamil Nadu near Puducherry the following day.On 15 November, well-marked low pressure area moved northwards along the Tamil Nadu coast, dropping huge amounts of rainfall over coastal Tamil Nadu and Andhra Pradesh with 24‑hour totals peaking at 370 mm in Ponneri. Chennai International Airport recorded 266 mm of rainfall in 24 hours. On 28–29 November, another system developed and arrived over Tamil Nadu on 30 November, bringing additional rain and flooding. The system dropped 490 mm of rainfall at Tambaram in 24 hours starting 8:30 am on 1 December. Very heavy rains led to flooding across the entire stretch of coast from Chennai to Cuddalore.
Flood in Chennai and Tamil Nadu regions[change | change source]
Between 9–10 November 2015, Neyveli received 483 mm (19.0 in) of rainfall; rains continued to downpour in Cuddalore, Chidambaram and Chennai. Continuing rains led to low-lying parts of Chennai becoming sunk by 13 November, resulting in the evacuation of over 1000 people from their homes. The flooding in Chennai city was worsened by years of illegal development and inadequate levels of flood preparedness.
The flooding in Chennai city was described as the worst in a century. The continued rains led to schools and colleges remaining closed across Puducherry and Chennai, Kancheepuram and Tiruvallur districts in Tamil Nadu and fishermen were warned against sailing because of high waters and rough seas.
Puducherry affected by the floods[change | change source]
Puducherry sustained relatively minor damage in November as the depression largely remained offshore; some trees were downed and several banana and sugarcane plantations at Kutchipalayam were severely damaged. Puducherry reported receiving 55.7 mm of rainfall over the 24-hour period from 14–15 November. Water entered several houses in low-lying areas, while three houses collapsed in Uppalam. On 5 December, the territorial government announced that nearly 9,000 hectares of paddy fields had been damaged by torrential rainfall, including 4,420 hectares of paddy fields in Puducherry,4,248.34 hectares in Karaikal and 287.15 hectares in Yanam. The government also reported 1,544 hectares of sugercane fields under cultivation had been damaged, along with 297.73 hectares of plantains, 231.9 hectares of tapioca and related tubers, 168.10 hectares of vegetable fields and eight hectares under betel-leaf cultivation. Proposed compensation rates would be as follows: 50,000 (US$850) per hectare for betel-leaf losses, 35,000 (US$595)) per hectare for plantains, 20,000 (US$340)) per hectare for paddy fields and 15,000 (US$255)) per hectare for losses of vegetables, tapioca, tubers and sugercane. Compensation scales had also been set for losses of cotton, lentils and flowers.
Consequences[change | change source]
Supplies of basic necessities, including milk, water and vegetables, were affected due to logistical difficulties. During the December floods in Chennai and the adjoining areas, milk packets sold for 100 (US$1.70), five times more than their usual cost. Water bottles and cans were sold at prices between 100 (US$1.70) to 150 (US$2.60). Vegetables were sold at least 10 (17¢ US) to 20 (34¢ US) over and above their normal average cost at the wholesale level.
Apart from basic necessities, fuel supplies and travel were greatly affected, especially in Chennai.In Chennai, over 1.5 lakh (150,000) street vendors sustained losses of over 300 crore (US$51 million). The persistent rainfall and flooding forced several major automakers in the region, including Ford, Renault, Nissan and Daimler AG, to temporarily halt production, resulting in estimated losses of up to 1000 crore (US$170 million).
References[change | change source]
The flood in Chennai on December 1 was a rare natural calamity and was not caused by any failure in the management of water releases from reservoirs.
Water discharge from the Chembarambakkam tank was steadily stepped up based on inflows and not all of a sudden. At night, the tank was ‘skillfully and judicially’ managed to moderate the flow in the Adyar River, said a statement issued by Tami Nadu Chief Secretary K Gnanadesikan refuting media reports that flooding of the Adyar River was due to improper management of water releases from Chembarambakkam tank, situated to the south-west of Chennai City in Sriperumpudur Taluk.
Adyar catchment full
The water level in the tank on December 1 was 5.08 ft with storage of 228 mcft. The rainfall in November 2015 in Chennai was 1,018 mm, which was the highest rainfall in November since 1918. All the tanks in the Adyar catchment reached full capacity and the surplus water flowed into the Adyar River.
Due to heavy rains, Chembarambakkam tank had copious inflows of water in the middle of November, and 18,000 cusecs was discharged into the Adyar River on November 17. On November 30, the water level was 22.05 ft with an inflow of 750 cusecs and outflow of 800 cusecs.
On December 1 morning, the water inflow started increasing and the water level in the Chembarambakkam tank was at 22.08 ft. As the inflow started increasing, the levels in the reservoir were carefully frequently monitored. Due to continuous heavy rains in the catchment, the tank started to receive heavy inflow in the afternoon, and continued till next day.
Based on the field situation, the engineers on the spot increased the outflow to 10,000 cusecs at 10 a.m., 12,000 cusecs at 12 noon and to 20,960 cusecs from 2 p.m. in the afternoon. This outflow was further increased to 25,000 cusecs at 5 p.m. and to 29,000 cusecs at 6 p.m. and maintained at that level till 3 p.m. next day and reduced gradually.
The maximum water level in the tank at 9 p.m. on December 1 was only 23.40 ft and had not reached the full capacity of 24 ft. The entire discharge was through the regulators and there was no uncontrolled discharge through the surplus weirs.
Engineers present at the Chembarambakkam tank site had taken the required decision based on the inflow into the reservoir. Similarly, water was being released from many other tanks and reservoirs, including Red Hills, Cholavaram and Poondi as a result of heavy inflow for which the local controlling officers took the decisions, he said.
Rebuts waiting for CM nod
“The allegation that they were waiting for instructions from the Principal Secretary, Public Works Department, and the Chief Secretary, and the imputation that the officers were awaiting the clearance from the Chief Minister are malicious and are canards not supported by the water release data of the reservoir,” he said.
The India Meteorological Department had only given an advisory of isolated extremely heavy rain but did not mention anything about 50 c.m. of rainfall as is being alleged in certain sections of the media, he said.
Flood warnings were given by the Collector, Chennai, and other officials in the media, and precautionary measures were taken up by the officials of the District Administration and Corporation of Chennai. The Collector of Chennai issued a first flood warning when the discharge reached 7,500 cusecs at 11.20 a.m. on December 1 and a second flood warning when the discharge reached 20,000 cusecs at 1.32 p.m. on the same day.
The warnings were telecast in television channels and FM Radio channels. There were at least 20 repetitions of the warning in the major regional channels, he said.
Immediately after the second warning, the Collector of Chennai and Corporation of Chennai, in close coordination with Chennai City Police, started the safe evacuation of people from low-lying areas. “Therefore, the allegation that the State Government had not given sufficient alert to the people is not true,” he said.