02 July 2019


How dams can control floods

By Aspire IAS

How dams can control floods

Theme: Purpose of Dams

  • world over,  dams are constructed mainly for the puposes of Irrigation, power generation, and flood control.
  • While the first two roles are acknowledged, the role of dams in flood control has always been underestimated.
  • It is unfortunate that in both irrigation and hydel projects, flood control is completely ignored.
  • Authorities always look to store the maximum amount of water in reservoirs during the monsoon season, which is then used for irrigation and generation of electricity during the summer months.

International practice:

  • It is an internationally accepted practice that the water level of a reservoir should be kept below a certain level before the onset of the monsoon season. This is so that when the monsoon rains come, there is space to store the excess rainwater and also so that water can be released in a regulated manner, thus preventing floods downstream when there is heavy inflow to the dams. For example, Thailand wisely brought down the water level in the dams in the country to below 60% of the storing capacity before the rainy season.
  • It is unfortunate that the maximum amount of water is stored in reservoirs even before the close of the monsoon, only to ensure greater electricity generation and irrigation. How the reservoir water was managed in the dams prior to the Kerala floods requires no explanation. While earlier too there was no practice of keeping space for greater storage of water, rainfall has never been as torrential as it was this year. Hence, there were no floods either.
  • It is difficult to predict what will happen during the ensuing northeast monsoon in Kerala in case of heavy inflow. Whatever be the extra quantity of electricity produced and area of land irrigated because of the risky storage of water in our dams, that cannot compensate for the loss of human lives, infrastructure and agricultural land. Nor can the agony caused by such destruction be compensated for. The estimated loss to the State runs into thousands of crores. It will take years to rebuild Kerala.

what is the practice at present?

At present, the At present, the task of dam and water management is vested with the Public Works Department, the Electricity Board, and the Irrigation Department. Even in normal conditions, given contradictory opinions from various departments, it is difficult to implement decisions. Hence, the State Dam Security Authority, if competent, should be entrusted with the task of water management in reservoirs and with taking decisions in emergency situations.

What is the Need of the Hour:

  • In 2015, Hydropower generation was only 16.6% of the world's total ectricity production. The tendency to hold the maximum amount of water in our reservoirs and ignoring the high risk involved can be attributed to our over-dependence on hydel projects to produce electricity. so,the need of hour is, one should think about non-conventional sources for electricity generation such as solar, wind, and tidal power. For example , solar generation in kochi airport can be copied in similar large-scale projects.
  • we have to reduce dependence on dams for power generation.
  • The State government, the State Dam Security Authority and the National Water Commission should all be prepared to take bold decisions together on water management so that there are no such devastating floods in the future.