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How dam water mis-management causes floods in riverside areas?

Dam water release protocols and floods

Dam water release protocol: Every year almost thousands of crore rupees are lost due to floods. Disasters are often classified as natural and man-made. We all know that floods are natural disasters but today floods can be caused due to human actions and infrastructure projects. Dam management was considered a major reason for the 2018 floods in Kerala that led to a loss of around Rs 50,000 crore.

Dams: A Construction of Concern

In the last few years, man-made structures such as dams, bridges, hydropower projects catchment, and enrochement in river beds have contributed to the cause of floods.

Floods of Tehri Dam (September 2010), Hirakud Dam (2009, 2011, 2014), Damodar dams, Krishna basin dams Chennai floods (December 2015) are some examples where dams worsened the flood disasters in the downstream areas. 

Floods caused by a dam are sudden and given the intensity of water, it destroys the lives and properties near it.

In an undammed river the flood water rises over a period of time which gives people time to respond but when dams are built over the river the water is released all of a sudden and the unpreparedness of people lead to the loss of many lives.

The Ranganadi hydroelectric project in Arunachal is the major reason for flash floods every monsoon season in the downstream areas of Assam. There are a lot of small and big hydropower projects built by China and India on the Brahmaputra river. Water from these stamps is sometimes released without prior notice or information. These dams give a false sense of security to the people living nearby. Every year millions of people are affected by floods but district-wise data about people left homeless in shelters less in the villages is not maintained. 

Ranganadi Hydro Power Station, Arunachal Pradesh | Source: NEEPCL

Assam floods, year-wise damage

YearArea Affected (in Mha)Population Affected(in millions)Damage to crop (area in Mha)Damage to houses 
2016No Record0.0030.000No Record
20170.285.60178.69111070
20180.041.3223.49102737
20190.237.36167.47117831
20200.195.79145.878122
Source: PIB

As per the national register of large dams 2019 of the Central water commission India has 5745 large dams of which 534 are completed in operational while 411 are in the construction stage. Further, there are 227 dams that are more than 100 years old and about 18% of dams have aid between 50 to 100 years.

According to the CAG report of 2017 submitted in parliament, there is an emergency action plan only for the 7% of the completed dams in India.

Dam water release protocol

dam water management in india

Rainfall is observed and inflow of water in reservoirs are recorded. When it seems that the reservoirs can no longer hold more water then the decision of releasing the water is taken.

Discharge warning is broadcasted to the public through warning stations, commercial radio stations, local TV network and SMS. Water outflow is regulated. But often these protocols are often ignored by the concerned authorities.

In 1961, the 50 m high Panshet Earth fill dam was largely completed and stored 200 hm³ cube at time of failure when it caused over 1000 fatalities and failure of downstream Masonry dam storing 140 hm³ water. The main reason behind this disaster was Embankment failure.

Embankments are constructed to create a safe area for habitation. In 1954, 160 km of embankment were built in Bihar to reduce the flood prone area which was estimated to be around 2.5 million hectares. Today, the state has a system of 3465 KM long embankments. But in place of decreasing the flood prone area from 2.5 million hectares it has increased to 6.89 million hectares. Although, India introduced the Dam Safety Act in 2021 for safe operation of Dams.

Dam Safety Act 2021

As per the Dam Safety Act 2021,

  1. All the specified dams are required to be inspected twice a year during the pre-monsoon and post-monsoon periods.
  2. The act states constituting a State Dam Safety Organisation (SDSO).
    The function of SDSO will be to have perpetual surveillance, inspection, monitoring the operation and maintenance of dams. In addition, keeping a database of all dams, and recommending safety measures to owners of dams.
  3. Dam owners will be required to prepare an emergency action plan, and carry out risk assessment studies for each dam at specified regular intervals.
  4. The act provides for two types of offences
    a. obstructing a person in the discharge of his functions, &
    b. refusing to comply with directions issued under the proposed law.

There are many more provisions in the act. Read here: Dam Safety Act 2021

Government of India with financial assistance from the World bank initiated dam rehabilitation and improvement projects in April 2012. Design Flood Review of 250 dams and Dam Safety Review Panel Inspection of 260 dams were carried out during the initial stage of the Project. Various instruments, which are installed in the dam, provide relevant information on the safety conditions of the dam. Laws are made in the country but we just need people to follow them. Following protocols can easily save the lives of thousands.

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