The State Government has signed up Indian Institute of Technology-Roorkee to conduct a long-pending ‘dam break analysis' on the ageing Mullapperiyar dam.
IIT-Roorkee has been given six months to come out with the report, according to the terms of the agreement signed in New Delhi on Wednesday.
Meanwhile, a meeting of the State Cabinet held here failed to take decision on convening a special session of the State Assembly on the dam safety issue.
SECOND MEETING
The Cabinet was scheduled to meet a second time late in the night and discuss the issue in more detail.
The Cabinet felt that it was necessary to consult the Opposition to ascertain its views on the matter, especially given the divergence of views, and emphasised the need for ‘hastening slowly.'
The safety issues relating to Mullapperiyar are heavily interlinked with the safety of the dams of the Idukki project downstream, says Mr Pareethu Bava Khan, former Additional Development Commissioner and Director, State Institute of Rural Development, Kerala.
The fact that the failure of the Mullapperiyar dam could lead to failure of the Idukki dam increases the magnitude of the risk associated with the continued use of the Mullapperiyar dam.
FLOOD ROUTING
The objective of dam-break modelling or flood routing is to simulate the movement of a dam-break flood wave along a valley or indeed any area ‘downstream' that would flood as a result of dam failure.
The key information required at any point of interest within this flood zone is generally: (i) the time of travel of flood water and maximum water level and discharge at different locations of river reach.
(ii) The nature, accuracy and format of information produced from a dam-break analysis will be influenced by the end application of the data. Giving a historical perspective, Mr Khan said the first European Law on dam-break was introduced in France in 1968 following the Malpasset dam failure.
INDIAN REGIME
Since then many countries have prescribed compliance, and in others, dam owners have established guidelines for assessment.
In India, risk assessment and disaster management plan has been made a mandatory requirement while submitting application for environmental clearance in respect of river valley projects.
Preparation of an emergency action plan after detailed dam-break study has since become a major component of dam safety programme here.
The extreme nature of dam-break floods means that flow conditions will far exceed the magnitude of most natural flood events.
SEPARATE STUDY
Under these conditions, the flow will behave differently to conditions normally considered for ‘normal river flow' modelling and inundation of areas.
This makes dam-break modelling a separate study for associated risk management and emergency action plan, Mr Khan said.
The National Committee on Dam Safety (NCDS) was constituted by the Government of India in October 1987 by broad-basing the then existing standing committee to include all the States housing a significant number of large dams.
The committee also monitors follow-up-action on recommendations of the report on Dam Safety Procedure circulated in July 1986.
Guidelines for Accord of Concurrence to Hydro Generating Schemes submitted under Section 8 of Electricity Act, 2003, brought out by Central Electricity Authority also specifically state that the scheme should meet the requirement of dam safety.
Checking the existing dams for their safety is important to delineate the necessary plan for rehabilitating them, Mr Khan said.