Dam-IASToppers
Editorial Notes

[Editorial Notes] Rains apart, blame the dams for floods

Dams that span decades, experience differential settlement of foundation, clog of filters, increase of uplift pressures, reduction in freeboard, cracks in the dam core, erosion of earthen slopes, and deformation of dam body itself increases the adverse impacts of floods.
By IASToppers
August 20, 2019

Contents

  • Why it was in News?
  • Introduction
  • Are dams of India resilient to climate change?
  • A look on future of Indian dams
  • Suggestions for dam management
  • Conclusion

Rains apart, blame the dams for floods

For IASToppers’ Editorial Simplified Archive, click here

Why it was in News?

  • The Koyna Dam in Maharashtra, which caused floods in the state after the release of water from its reservoir was not timed properly.

Koyna-Dam-iastoppers

Introduction

  • Heavy and erratic rainfall is one of the reasons for floods in several states. But that is often coinciding with dams being full due to poor management, resulting in dam-induced floods.

Koyna-Dam-1-iastoppers

  • For some states under deluge such as Maharashtra, Karnataka and Kerala are being questioned over their flood management system.
  • Due to fear of dry conditions in future, dam operators think of storing as soon as water is available in monsoon but that proves costly during flood as then there is no alternative but to release all the inflow downstream.

How the dam activity affects the flood?

Koyna-Dam--2-iastoppers

  • Delaying in release of water from dam have a huge influence on worsening the flood situation.
  • Also, a sudden release of water may cause the situation worst especially in case of heavy rainfall, coinciding with the flood peak.
  • Moreover, the management of operations of reservoirs is sometime missing due to the lack of coordination both at reservoir level as well as the basin level.
  • For example, at the beginning of the monsoon, reservoirs in Maharashtra and Karnataka were filled up. But the people responsible for operations work do not work with the Indian Meteorological Department to understand the pattern of rainfall, leading to flood.

Are dams of India resilient to climate change?

dam-safety-bill-iastoppers

  • India’s dams are old and ageing and there is an urgent need to assess their safety, carry out repairs, or dismantle them to prevent dam failure-related disasters.
  • As per recently published Dam Safety Bill, there are 5,745 reservoirs in the country, of which, 293 were more than 100 years old.
  • The age of 25 per cent of dams was between 50 and 100 years and 80 per cent were over 25 years

A look on future of Indian dams

In 2025

  • 500 large dams will cross a minimum age of 50
  • 237 large dams will turn 65 years
  • 300 dams will turn 75 years of age
  • 65 large dams will turn 125 years of age

In 2050

  • 1,115 large dams would have aged at least 54 years by 2025.

Suggestions for dam management

Koyna-Dam--3--iastoppers

  • There is need for the guideline on how the dam should be supposed during the monsoon to optimize flood moderation for the downstream area.
  • If the amount of water flowing to the reservoir was known beforehand, the water level in the reservoir could be managed. This could be done through the simulation models which depend on the size of the catchment.
  • There should be a clear-cut protocol for maintaining the reservoir levels.
  • Also real time flood monitoring and methodologies calculating the flow of the river, could effectively help in managing dam levels under variable rainfall patterns. They are available in the country but used rarely.
  • There should be coordination at state and inter-state level for proper management of the dams and how operation of reservoirs should be done. There should be a body to oversee the coordination.

Conclusion:

  • As a dam ages, the impact of the erosion of earthen components, through the dam body and foundations, and sedimentation occur at a different rate than assumed.
  • Therefore, there is an urgent need to assess their safety, carry out repairs, or dismantle them to prevent dam failure-related disasters
  • In the era of climate change, following the rule curve is still more urgent.

IT’s Input

What is Rule curve in Flood Management?

  • The rule curve divides the storage volume of a reservoir in zones where different strategies for demand supply will be applied.
  • The limits of each zone may vary seasonally or remain constant during the whole year.
  • Such tool may be used for flood control or water conservation during long dry spells.

 

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