The Polavaram dam involves a huge cost but its benefit will be limited
400,000 MAY BE DISPLACED
The environmental impact assessment (EIA) of the project says 276 villages will be affected; an estimated 177,275 people live in these villages. The Polavaram Project Environmental Impact Appraisal Report of 1985 expected 150,697 people to be displaced in 226 villages.
But the population of these villages according to the Census 2001 is much higher—236,834. State officials find it hard to explain the difference of 59,559 while estimating the number of people who will be displaced.
Further, in the past 10 years, the population of these villages would have increased. If one takes into account 15,105 households (60,118 persons) that would be displaced by the two canals, then one arrives at the figure of 317,150 persons affected.
Researchers Tony Stewart and V Rukmini Rao, estimate the number of impacted people would be about 400,000 after adjusting population growth in the past decade. They conducted a detailed survey of the project-affected areas for non-profit Gramya Resource Centre for Women in Andhra Pradesh.
MORE WATER FOR IRRIGATED AREAS
According to the documents relating to the Polavaram project, 291,000 ha of new land will be brought under irrigation—129,000 ha by right canal and 162,000 ha by the left canal. But government of India’s official data shows 71 per cent of the right canal command areas are already under irrigation since 1999. The International Water Management Institute based in Sri Lanka that studied the Krishna-Godavari river link found that 95 per cent of the areas to be irrigated by the Polavaram dam through the right canal were already irrigated; the rest five per cent areas were not under cultivation.
The government has already built two lift irrigation projects parallel to the canals—Tadipudi and Pushkharam—that will irrigate around 161,874 ha of the total area supposed to be irrigated by the Polavaram project. The Chagalnadu lift irrigation scheme, the Torrigedda and the Yeleru schemes already irrigate 51,800 ha. In effect, the Polavaram dam may irrigate only 80,937 ha of new land.
What’s more, irrigation may be hampered by siltation in the river. An analysis of 13 existing irrigation projects shows they could partly irrigate 1.3 million ha against the potential of 1.68 million ha.
DESIGN PLAYS DOWN FLOOD THREAT
Environmental clearance for the Polavaram dam is based on a 2005 environmental impact assessment (EIA). But the Central Water Commission (CWC) changed its flood situation estimate in 2006 which has not been incorporated in the design. The Polavaram project was designed in 1980s and updated in 2005. It went by the probable maximum flood (PMF) level of 102,000 cubic metre per second (cumecs) for designing the spillway. The CWC, however, did not accept the design; it had originally accepted the spillway designed for a flood level of 102,000 cumecs on the premise that the project was a barrage.
When Godavari experienced high flood in August 2006, submerging about 370 villages for days in Andhra Pradesh, CWC made a fresh assessment of PMF at 140,000 cumecs. Consequently, CWC directed the state government to revise the Polavaram project design to handle 142,000 cumecs flood level for its spillway.
However, the National Institute of Hydrology of the Union Ministry of Water Resources estimated the PMF at 169,920 cumecs. The dam break analysis for the Polavaram dam is an essential part of its EIA.
The institute found that if the dam bursts, the peak flood will be of 198,200 cumecs. This means the project’s EIA is flawed and downplays the threat of flood. “Based on recent rainfall trends and flood history, a peak flood of 250,000 cumecs is a reality. This will wash away the dam,” says T Hanumantha Rao, former chief engineer with Andhra government. Though CWC changed the maximum flood estimate from 102,000 cumecs to 142,000 for the dam’s spillway design, Andhra Pradesh has not changed the back water level estimates based on the new PMF.
Odisha now says that the revised design would lead to very high inundation in Malkangiri.
UNSAFE EMBANKMENTS
The project will submerge villages along the Sabari river in Konta block of Chhattisgarh’s Dantewada district. In Odisha, villages along the Sabari and Sileru rivers (tributaries of the Godavari) in Motu block will be submerged. Andhra Pradesh has suggested constructing 30.2-km-long protective walls in Odisha and 29.12-km-long walls in Chhattisgarh to avoid submergence.
The embankments’ height will range from 10-30 metres and would cost Rs 600 crore. But there have been no assessments to gauge the maximum flood level that would impact the embankments.
The Odisha government has opposed the embankments, saying large reservoirs with high spillway capacity have been constructed on Kolab (Sabari), Balimela and Lower Sileru. Water from these reservoirs will flow into the Godavari, thus impacting submergence and harming the embankments’ safety. The forest clearance to the Polavaram project was given on the condition that Andhra Pradesh will construct embankments to avoid submergence.
But for these forestland will have to be diverted. There has been no attempt to assess the forestland that will be diverted for the embankments.
The forest clearance given in July 2010 put a condition that there would be no submergence and displacement in Odisha and Chhattisgarh. The environment clearance given in 2005 to the Polavaram project proposal did not mention the embankments in Odisha and Chhattisgarh. This came to light only when the Central Water Commission gave clearance for the project in January 2009.
“This is a violation critical enough to scrap the environmental clearance,” says activist Himanshu Thakkar. In February 2009, MoEF’s Expert Appraisal Committee for River Valley and Hydroelectric Projects directed the Andhra government to conduct public hearings in both the states for the embankments. The state government has not done this.
DAM WILL SUBMERGE VILLAGES UP TO A DISTANCE OF 150 KM
- The Polavaram project will harness the waters of the river Godavari by building a 45.72- metre-high, 2.32-km-long dam
- The earth and rock-filled dam will have a storage capacity of 551 million cubic metre (mcm) and power generation capacity of 960 MW. The initial proposal was for a storage reservoir with a capacity of 424.8 mcm and full reservoir level (FRL) of 45.72 metre
- The water from the dam reservoir will irrigate 291,778 ha of agricultural land in the districts of Krishna, East and West Godavari and Visakhaptnam through two major canals
- The dam will submerge 276 villages in Andhra Pradesh’s Khammam and East and West Godavari districts, Odisha’s Malkangiri district, and Chattisgarh’s Dantewada district, up to a distance of 150 km
Courtesy: Down To Earth