Kerala Power Minister MM Mani, during the ongoing Assembly session, announced that the Central Water Commission (CWC) has approved the Emergency Action Plan (EAP) for 21 dams in the state. The EAP for three more dams will soon be approved by the CWC, the Indian government’s technical body for water resources. These dams come under the Kerala State Electricity Board (KSEB). Here’s an explainer on what this means.
What is EAP?
The Emergency Action Plan is a document that defines the notification procedures to be followed in the event of a potential disaster. These documents help to identify situations that could pose a threat to the dams, as well as to plan a quick, effective response to prevent its failure.
It also details plans to warn and protect residents living in the downstream areas and to prevent property damage from excess water released from the dam spillways or an uncontrolled outflow of water from the breached portion of a dam.
This Emergency Action Plan has been prepared by Kerala State Electricity Board Limited (KSEBL) in collaboration with CWC’s Central Project Management Unit (CPMU).
The EAP lists out, in detail, the roles and responsibilities of various stakeholders involved (like dam owners, disaster management body, district collectors and media), availability of facilities (such as power and telephones), contact numbers, the floodplains or places likely to be inundated, and locations where people can be relocated, among others.
The EAP, inter alia, mandates apprising the District Disaster Management Authority of any distress signs in a timely manner, and signboard installed in different locations at a dam site and operation room, which shows signs of distress and corresponding levels of alert and remedial actions.
It identifies severe storms or inclement weather, tropical cyclones, earthquakes and sabotage as emergency situations. The EAP explains the various types of dam failures, that is, failures due to minor, excessive or uncontrolled seepage through the dam or foundation, the sliding of embankment or foundation, structural failure or collapse of any non-overflow portion of the dam, spillway or spillway gates, and the overtopping of the embankment, which could lead to uncontrollable erosion of dam crest.
The EAP mentions ‘Blue alert’ as a 'watch condition' and an ‘Orange alert’ indicative of a dam condition that is progressively getting worse. A 'Red alert' means that the dam is either in immediate danger of failing or has already failed.
How the EAP is more structured this year
According to Bibin Joseph, Chief Engineer (Civil – Dam Safety and DRIP), KSEB, the works on drawing up the EAP started in 2017 and was revised further after the floods in August 2018.
“An Emergency Action Plan was issued in 2006 based on international standard practices. However, the CWC revised these and issued the official EAP guidelines in 2016, for the Hirakud dam in Odisha. This was the first EAP published on CWC site. After this, various stakeholders and dam owners started drawing up EAP documents for their dams and published on their websites,” elucidates Bipin.
In 2017, the KSEB availed of the services and expertise of various consultants to prepare the EAP for its dams but the CWC did not approve it.
“We then prepared new guidelines to include the rule curve (levels that specify the empty space to be maintained in a reservoir) and the inundation maps, which specify the depth of dam, the velocity of water and the time period in which the excess water released is likely to reach a particular area,” Bipin further explains to TNM.
“Hence, the updated EAP is more structured than its earlier versions,” he adds.
This EAP, Bipin says, is only a tier-one document prepared based on Dam Break Analysis (the analysis of possible failures in a dam due to a disaster), carried out using the digital elevation model (DEM), the digital representation of terrain elevations. And for the first time, the dataset for the DEM was derived from Japan Aerospace Exploration Agency (JAXA), which relied on Satellite imagery and Google Maps.
“The DEM will accurately tell how many places will be subject to flooding. So, the accuracy will be higher in tier-two and tier-three documents. Hence, these guidelines, including DEM and contact numbers, have to be revised every year,” the KSEB official says.
The EAP is a voluminous document, which the KSEB officials say, will be difficult for the people in panchayats to fully comprehend. “Hence, we are trying to bring out a condensed version of the EAP, summarising various alerts, the floodplains and the evacuation plan,” says Bibin.