HYDRAULIC SAFETY OF DAMS

 HYDRAULIC AND AGRICULTURE DEFECTS OF POLAVARAM DAM

Right fromthe beginning the Engineering experts of AP state Government and the Central Water Commission have been knowingly committing grave mistakes in the design of he dam and in estimating the cost benefit ratios  on improper data.For instance the National Water Development Agency (See web site:see paras

http://nwda.gov.in/index4.asp?ssslid=122&subsubsublinkid=32&langid=1

http://nwda.gov.in/writereaddata/linkimages/6907034768.pdf      [see para 6.2.4]

http://nwda.gov.in/writereaddata/linkimages/4129963896.PDF    [ see last paragraph]
http://nwda.gov.in/writereaddata/linkimages/6479885403.PDF    [ see para 8.1 and 8.2]

indicates that while     Central Water Commission suggested for off take canal at    33.53 m 110ft elevation with a discharge point in Krishna basin at about  18.29 m 60ft,  the AP state Government for its own vested interests for increasing the elevation of the Polavaram dam on a large scale insisted on increasing the level of Polavaram at off take level of 40.23 m 133ft with a discharge point in river Krishna at an elevation of about 27.97 m   92ft.  

Moreover the Central Water Comission always considered Polavaram as a barrage structure for purposes of design flood and thereby accepted for spillway design a 500-year return flood of 36 lakhs cusecs while the CWC guidelines insist on considering for the size of Polavaram dam a Probable Maximum Flood or a 1000-year return flood for spillway design purposes.  

Moreover the NWDA website on Polavaram project clearly states under table 9.2 of the report under the Polavaram right canal out of 1,62,691ha of irrigable land area only 44,000 ha is unirrigated while the rest of the land is irrigated under different sources like canals, lift irrigation systems,borewells and village tanks.   Hence there is only about 1 lakh acres of land available to be irrigated by water from Polavaram dam while the claim is made for irrigating about 3 lakh acres under this right canal.  In fact independent experts have collected field data which shows that about 95% lands under the left polavaram canal is already irrigated and only 5% land may get benefitted by polavaram dam project.see the following web site:

http://www.weap21.org/downloads/NRLP.pdf    [ see pages 65 and 66]

Similarly under the left canal of the Polavaram project while about 4 lakh acres is proposed to be irrigated with water from Polavaram dam about 2.5 lakh acres is already under irrigation under the lift irrigation schemes,canals, medium irrigation projects, borewells and village tanks with the result that only about 1.5 lakh acres can be fed by Godavari waters from Polavaram project.  If these two true facts are taken into conisideration the cost benefit analysis of Polavaram dam will be negative and there is no feasibility for taking up this project to promote national economy  and how can planning commission promote.such project that is  risky as also not economically viable but also verycostly, uneconomical and  detrimental to public interests