The NHPC Limited has received investment and environmental clearance from the Government of India to start construction of the Middle Subansiri Hydropower Project, following progress in the Lower Subansiri project.

Key developments

• Middle Subansiri Project
  • Approved by the Central Government with full investment clearance.
  • Installed capacity: more than 1,600 megawatt.
  • Environmental clearance granted.
  • Tendering process for construction has begun.
• Lower Subansiri Project
  • Two units are already in commercial operation, generating 500 megawatt.
  • The third unit is expected to begin commercial production shortly.
  • All eight units are projected to be operational by March 2027, if timelines are met.

Operational features and concerns

• The Lower Subansiri project is affected by seasonal variation in water flow:
  • During the dry season, only one or two units operate at a time.
  • Water is conserved to run all units during peak demand hours.
  • At least one unit is kept running continuously to ensure minimum river flow in the Subansiri River.
• During the monsoon season, water availability is sufficient to operate all units.

Flood management measures

• Unlike several hydropower projects in the Himalayan region, the Lower Subansiri project includes flood moderation features:
  • Flood cushioning and storage capacity up to 15 metres.
  • Designed after assessing historical high flood levels of the Subansiri river.
  • Officials state that the project should not significantly increase downstream flood risk.

One-line wrap

The clearance of the Middle Subansiri project marks a major step in expanding hydropower capacity in Northeast India while highlighting the need for careful river and flood management.

Exam Hook – 

Consider the following statements:

1. The Middle Subansiri Hydropower Project has received both investment and environmental clearance from the Central Government.
2. The Lower Subansiri Hydropower Project has no provision for flood cushioning or flood storage.
3. Seasonal variation in river flow affects the operation of hydropower units in the Subansiri basin.

Which of the statements given above are correct?

(a) 1 and 3 only
(b) 1 and 2 only
(c) 2 and 3 only
(d) 1, 2 and 3

Correct answer: (a)

Source