Flood Management and Response in Chennai and its Suburban Areas – SAI India

Flood Management and Response in Chennai and its Suburban Areas – SAI India

  1. Introduction

The Chennai floods in 2015 brought the normal life to rubble. The floods claimed 289 lives, inundated 23.25 lakh houses, disrupted power and telecommunication services, halted transport facilities and caused extensive damage to public as well as private property. The aftermath of the floods was overwhelming, and it took a long time to get back to normalcy. The flood relief measures were also heavily handicapped because of the lack of institutional mechanisms for timely and effective relief activities. The absence of a significant Disaster Management Plan by the state Government of Tamil Nadu (GoTN) to effectively reduce the cost and devastation in the aftermath of natural disasters was clearly evident.

In this context, SAI India conducted a Performance Audit of “Flood Management and Response in Chennai and its Suburban Areas.” The focus of this report was aimed to assess not only the economy, efficiency and effectiveness in disaster management programmes but also the preparedness of the state to effectively manage natural disasters and the factors hindering the same. The report emphasized the agonizing impact of the floods and the lack disaster mitigation in the roles played by various government bodies.

  1. Aims and objectives of the report:

The objectives of the report were to assess the:

  1. Effectiveness in implementing the Master Plans for orderly development of the city with due regard to preservation of water bodies and structures;
  2. Effectiveness in addressing the issue of encroachments, which hinder free flow of rain water;
  3. Economy and effectiveness in carrying out flood management programmes;
  4. Efficiency and effectiveness in disaster management; and
  5. Effectiveness of internal control mechanism, including performance evaluation and monitoring.

  1. Principal Findings

The 2015 December floods was not the first catastrophic flooding that the city has faced through its existence. Floods have hit the city in 1943, 1976, 1985, 1998, 2002 and 2005 due to heavy rains and cyclonic activities. However, GoTN (Government of Tamil Nadu) has not prepared plans to effectively combat natural disasters. The 2015 Chennai floods was another example to show the lacunas in the preparedness in context to disaster management and relief measures. Lack of proper project management coupled with the absence of implementation of several plans is the reason for the government’s poor response to a sudden natural disaster.

The results of this Audit brought out the deficiencies in urban planning and ineffective enforcement of statutes and Master Plans, which had an impact on natural water bodies. The improper maintenance of water bodies led to hampering the free flow of excess water to sea and paved the way for flooding in the city. This particular issue is twofold: the first being poor project management capabilities by the Government of Tamil Nadu (GoTN) and secondly, the lack of necessary restraints on encroachments. Few of such instances were as follows:

  1. There were several government-approved plans to restore and augment capacities of tanks and reservoirs, to reduce surface runoff and to meet the ever-increasing drinking water demands of the water-starved city. Considering the catastrophic floods in 1976, the Nucleus cell constituted by Government had recommended the creation of two new reservoirs in the upstream of Chembarambakkam tank influencing Adyar River to capture 1.57 thousand million cubic feet of water. Audit noticed that the proposal to create a reservoir at Thiruneermalai across Adyar river in 1987 failed as the site became populated and requisite land was not available.  Two new reservoirs were not created and the action to increase the storage capacity of existing six tanks, which would also meet the drinking water needs of the city was not completed due to land acquisition issues and faulty design.
  2. With a view to mitigate flooding in Chennai due to frequent heavy rains, flood protection works for improving macro drainages in four basins of the city, taken up in June 2010, were not completed due to improper planning, non-acquisition of land, lack of co-ordination with other departments, and non-eviction of encroachments in waterways, where such works were needed to be executed.
  3. Storm Water Drains (SWDs) are intended to collect surface rain water from the streets and discharge into water courses. An efficient, well designed and well-maintained storm water drainage system would minimize the level of water logging and damage, therefore would play an important role in flood management. There were recommendations of Anna University in Chennai, (by using Airborne Laser Terrain Mapping (ALTM) and Geo Information System) which proposed inter-linking of SWDs with temple tanks. Further Greater Chennai Corporation (GCC) has prescribed norms of rain water harvesting structures in SWDs at 30m intervals along the roads. However these were not complied with which ultimately caused inundation of flood water in 2015.
  4. National Institute of Hydrology, Roorkee (NIH) has evaluated rain-fall intensity of 48.63 mm per hour. Greater Chennai Corporation, (GCC) however, adopted the rainfall intensity of 31.39 mm per hour and constructed SWDs for a length of 345 km during the years 2011-14. The construction of lower capacity SWDs also contributed to the above floods.
  5. Flood disaster would be considered natural if the quantum of outflow from the dam is equal to the inflow flood. If, however, due to very existence of a dam, the outflow exceeds the inflow, the disaster can be logically classified as man-made. Chembarambakkam Tank is one of the largest tanks which supplies drinking water to Chennai city, the capacity of storage is 3.645 TMC of water. The surplus course of this tank joined Adyar River at Thiruneermalai. On 1 December 2015, at 2 pm, when the storage stood at 3.377 TMC, which was 0.268 TMC less than the total capacity of the tank, the discharge of water was abruptly increased from 12,000 cusec to 20,960 cusec and further increased 25,000 cusec and 29,000 cusec. The continuous discharge of water at 29,000 cusec into the Adyar River coupled with surplus water from the upstream tanks and catchment area, subsequently caused huge flow of flood waters into Adyar River. GoTN had failed in carrying out the recommendations of various experts/committees on creation of additional storage capacity in the upstream of Chembarambakkam Tank, construction of diversion channel to Adyar River and construction of two check dams across the river. Due to all these factors, it was concluded that the flooding was man-made in terms of the CWC guidelines.

After learning from the disaster of the 2015 floods, GoTN acted swiftly and conducted a special drive to evict 4,531 out of 23,840 slum families living along the margins of Adyar and Cooum rivers. The banks of Adyar river had been widened and deepened at vulnerable points in Chennai Metropolitan area. Greater Chennai Corporation took up works to construct 292 kms of SWD. The draft Disaster Management Plan for the state was approved by GoTN in October 2016.

GoTN had taken following Multi-Dimensional measures as a part relief activities:

  1. Around 14 lakh people were evacuated from flood affected areas to flood relief centres;
  2. About 600 boats were used to ferry people from flood affected areas;
  • Around 5500 relief shelters were operated by GoTN during time before and after flood for the affected people;
  1. Approximately 75 lakh people were treated in 73,457 special medical camps organised by the Health Department;
  2. Around 1536 veterinary medical camps were conducted wherein around 1.5 lakh cattle and domestic animals were treated;
  3. 453 MTs of Milk powders were distributed to the flood affected people;
  • To control epidemic disease, around 2000 MTs of bleaching powder were distributed every house-hold in CMA area (Half Kg per household) and chlorinated drinking water were distributed through distribution networks and tankers; and
  • Source reduction and vehicle mounted fogging machines were put into to control the mosquito breeding.

  1. Conclusion

The State of Tamil Nadu is prone to sudden torrential rainfall and frequent cyclonic effects. Though GoTN has carried out the food, water, shelter and medical needs of the flood affected people, majority of these are part of state government’s day to day business.  Our report has concluded that the 2015 Chennai floods was a man-made disaster. Many plans need to be put in place to mitigate inevitable disasters. GoTN should speed up implementation of plans to face this magnitude of severe disasters.


CAG’s Report (State Government) No.4 of 2017 – Performance of Flood Management and response in Chennai

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