A critical study reveals that nearly 50% of the Malankara dam's capacity is lost to silt, creating a dangerous situation for the Thodupuzha and Muvattupuzha rivers.

Key Takeaways

  • Silt occupies 48.95% of the Malankara dam's total storage capacity.
  • Reduced capacity complicates water management and flood prevention.
  • A desilting project covering an 8km stretch has been approved.
  • The project is expected to be completed within three years.

The Malankara dam in Idukki, a vital component of the Muvattupuzha Valley Irrigation Project (MVIP), is facing a severe capacity crisis. According to a 2021 study by the Kerala Engineering Research Institute (KERI), silt has occupied 48.95% of the reservoir's total storage capacity, significantly diminishing its ability to manage water inflows.

This reduction in volume poses a direct threat to the downstream areas of the Thodupuzha and Muvattupuzha rivers. With the reservoir's full level set at 42 meters, the lack of available space means that during heavy monsoon seasons, officials struggle to regulate water release without risking catastrophic flooding in surrounding settlements.

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Why This Matters

BozokMedia analysis shows that the dam's operational dependency on the Moolamattom powerhouse creates a complex hydraulic challenge. The dam primarily stores tailrace water released during electricity generation. When power demand peaks, the inflow increases; however, if the rivers are already at dangerous levels, the dam has nowhere to safely store the excess, creating a high-stakes balancing act between energy needs and public safety.

The depletion of reservoir volume due to sedimentation is a silent killer for dam safety and flood mitigation strategies.

To address this, authorities have greenlit a major desilting operation. The plan involves clearing silt along an eight-kilometre stretch upstream from the dam to the Kanjar bridge. This massive undertaking is projected to take three years, with the contracting company offseting costs by extracting and selling the sand from the reservoir.

Historical Background

The Malankara dam functions as a diversion dam rather than a traditional storage dam. Because its inflows are heavily dictated by the Kerala State Electricity Board's (KSEB) power generation cycles, it does not follow a strict rule curve, making the impact of siltation even more unpredictable for local water management authorities.

Did You Know?: Desilting projects can actually be self-funding in some cases, as the valuable sand and minerals extracted from the reservoir floor can be sold to the construction industry.

Frequently Asked Questions

1. How does silt affect the dam?
It reduces the volume of water the dam can hold, making it harder to prevent floods during heavy rainfall.

2. What is being done to fix this?
A desilting project covering 8km of the upstream area is being implemented to restore the reservoir's capacity.