12. VIOLATION OF  ENVIRONMENTAL RULES  IN CASE OF  POLAVARAM DAM  PERHAPS LEADING TO ITS FAILURE:

For obtaining such environmental clearances the dam proponents have to prepare the dam safety report including the dam break analysis, risk assessment and Emergency preparedness plans as specified under the rules of Environmental Protect Act and also the dam safety guidelines. 

http://envfor.nic.in/welcome.html  

As per the above website of  the Union Ministry of  Environment and Forests the project authoriteis must submit an application for Environmental clearance for  irrigation, industrial or other projects as secified under schedule-I.

As per the EIA notification dt.27-1-1994 as ameneded upto 13-12-200 Environmental clearance requires the project authorities to submit application in the proforma speicified in Schedule-II, accompanied by a project report which shall include an Environmental Impact Assesment (EIA) report, an Environmental Management Plan and details of public hearing as specified by the Central Government.    This application form specified under the Schedule includes preparation of reports for the following items also under the different serial numbers specified below:

      10)    (a)  Number of Villages and population to be displaced 

                (b)  Rehabilitation Master Plan

      11)    Risk Assessment Report and Disaster Management Plan

      12)    (a)  Environemntal Impact Assessment (EIA)

               (b)  Environmental Management Plan (EMP)

               (c)  Detailed feasibility Report

               (d)  Duly filled in questionnaire

13)    Details of Environmental Management Cell

 

13. VIOLATION OF    DAM  SAFETY GUIDELINES  OF  CWC  PERHAPS RESULTS IN FAILUE OF POLAVARAM DAM:

Due to the catastrophic failure of Teton Dam and other dams all over the World,ICOLD organised an international workshop on Dam Safety at New Delhi and recommended to all the countries to promote dam safety.consequently,Government of India established a Dam Safety Organisation in the Central Water commission in 1979 and formulated guide lines on Dam safety in public interest for implementation by all the state Governments.:For detailed information on the role of Union Government water Resources Ministry to get Dam Break analysis Reports for major Dams,  See pages 32,33 and 34 on the web site:

 http://wrmin.nic.in/editors-conference.pdf

http://wrmin.nic.in/publication/ar2000/ar00ch10.html 

The guidelines on dam safety sent  by the Central Water Commission to the state Governments in 1986 includes an item on  Emergency Preparedness Plans  as can be seen from the website:http://www.dams.org/docs/kbase/studies/csinanx.pdf   [see item 9 on page 11 ]

 If necessary, please copy the web site and use GOOGLE search engine to get at the correct information

The details to be furnished under the Emergency Preparedness Plans as per World Bank guidelines can be seen from the Website:

http://wbln0018.worldbank.org/Institutional/Manuals/OpManual.nsf/BProw/1281729955CF0EDB8525672C007D0778?OpenDocument

For the convenience of the reader the Emergency Preparedness Plans prepared under the Dam Safety Act, 1972 [U.S.A] including the inundation maps prepared for each of the dams in California is presented in the following website:

http://www.abag.ca.gov/bayarea/eqmaps/damfailure/dfpickc.html

As an example for indian engineers to take necessary action to make Dam Break Analysis,Risk assessment and Disaster management plans as contemplated by the Union Ministry of Environment and forests and the Union Ministry of Water resources uder the rules,regulations and guidelines formulated in tune with the international standards on Dam safety and environmental protection,the case study of HORSE TOOTH RESERVOIR in Colorado,USA is presented as can be seen from the web sites: : http://fcgov.com/oem/dam-failure.php

14. DAM-BREAK  ANALYSIS  FOR  POLAVARAM  ROCK-FILL  DAM

If the dam break analysis and risk assessment is made alternate actions can be taken to protect public health and the environment. For instance in USA some of the dams found unsafe are completely dismantled. In some cases the embankments of the dam are strengthened and others, the storage are reduced for operation so that in the event of a dam failure, the costs of damage will be restrained to lie within the tolerable limits. The engineers can plan for alternate courses of action by reducing the heights of dam and their storages and avoid loss of life and property for achieving more or less the same economic gains by following the alternate course of action.  To give an example the case study of Horsetooth reservoir case is presented to serve as a model for preparing similar risk assessment reports for Polavaram dam.  For details see the website: http://www.usbr.gov/gp/ecao/horsetooth/horsetooth_safety_dams/mod/chapter5.htm 

 

In this paper the dam break analysis for an irrigation project on Godavari is carried out by using the popular national weather service dam break flood forecasting model (NWS DAMBRK) for assessing the likely maximum flood discharge and elevation to be attained by the flood inundation for several habitations down steam in the eventuality of a dam failure. 

NWS – DAMBRK  MODEL  DESCRIPTION:

            The U. S National Weather Service (NWS) initially developed DAMBRK program (Fread, 1984) in 1977.  Research has been ongoing in developing improvements in the  DAMBRK  model allowing it to have an increasing range of  application ( Fread, 1989). The model has wide applicability, it can function with various levels of input data ranging from rough estimates to complete data specification, the required data is readily accessible and it is economically feasible to use with minimal computational effort on microcomputers.

DAMBRK model can be used to develop the outflow hydrograph from a dam breach and hypothetically route the flood through the downstream valley. The governing equations of the model are the complete one-dimensional Saint-Venant equations of unsteady flow  which are coupled with internal boundary equations representing the rapidly varied flow through structures such as dams and embankments which may develop a time dependent breach. Also, appropriate external boundary equations at the upstream and downstream ends of the routing reach are utilized. The system of equations is solved by a nonlinear weighted four-point implicit finite difference method. The flow may be either subcritical or supercritical.

            The hydrograph to be routed may be specified as an input time series or it can be developed by model using specified breach parameters (size, shape, time of development). The possible presence of downstream dams which may be breached by the flood, bridge / embankment flow constrictions, tributary inflows, river sinuosity, levees located along the downstream river, and tidal effects are each properly considered during the downstream propagation of the flood. DAMBRK may also be used to route mud and debris flows using specified upstream hydrographs. High water profiles along the downstream valley, flood arrival times, and hydrographs at user selected locations are the standard DAMBRK model output.

DATA REQUIREMNTS FOR NWS – DAMBRK MODEL

The DAMBRK model was developed by National Weather Service (NWS) so as to require data that was accessible to the forecaster.  The input data requirement are flexible in so far as much of the data may be ignored (left blank on the input data cards or omitted altogether) where a detailed analysis of a dam break flood inundation event is not feasible due to lack of data or insufficient data preparation time.  Nonetheless the resulting approximate analysis is more accurate and convenient to obtain than that which could be computed by other techniques.  The input can be categorized into two groups.

The first data group pertains to the dam: (the breach, spillways, and reservoir storage volume).  The breach data consists of the following parameters: T (failure time of breach, in hours), b (final bottom width of breach), Z (side slope of breach), hbm (final elevation of breach bottom), ho (initial elevation of water in reservoir), hf (elevation of water when breach begins to form), and hd (elevation of dam).  The spillway data consists of the following : hs (elevation of uncontrolled spillway), Cg (coefficient of discharge of gated spillway), Cd (coefficient of discharge of crest of dam), Qt  (constant head independent discharge from dam).  The storage parameters consists of the following: a table of surface area (As) in acres or volume in acre-ft. and the corresponding elevations within the reservoir.  The forecaster must estimate the values of T,B,Z,Hbm , and Hf .  The remaining values are obtained from the physical description of the dam, spillways, and reservoir. In some cases Hs, Cs, Hg and Cg and Cd  maybe ignored and Qt used in their place.

The second groups pertains to the routing of the outflow hydrograph through the downstream valley.  This consists of a description of the cross-sections, hydraulic resistance coefficients, and expansion coefficients.  The cross-sections are specified by location mileage, and tables of top widths (active and inactive) and corresponding elevation.  The active top widths may be total widths as for a composite section, or they may be left floodplain, right flood plain, and channel widths.  The channel widths are usually not as significant for an accurate analysis as the over bank widths.  The number of cross-sections used to describe the downstream valley depends on the variability of the valley widths.  They also depend on the availability of cross-section measurements. However, a minimum of two must be used.  Additional cross-sectional data to be input by the forecaster according to such criteria as data availability, variation, preparation time etc.  The number of interpolated cross-sections created by the model is controlled by the parameter DXM which is input for each reach between specified cross-sections.  The expansion-contraction coefficients (FKC) are specified as non-zero values at sections where significant expansion of contradictions occur.  But they may be left blank in most analyses.

INPUT DATA USED FOR RP SAGAR DAM ON GODAVARI RIVER

 

  1        

0  

      0        

3 

13        

      0        

0

1

 

1130.2      

637

333.0    

238.0    

160.0     

60.0     

22.5        

        0

 

55.0    

45.72     

40.0     

36.0     

 32.0     

24.0     

18.0     

13.5

 

50.0    

53.32     

0.05     

15.0    

450.0      

0.5     

 13.5      

0.0

 

53.32    

   53.32      

0.0    

35.72      

0.0   

9900.0     

4000

1200.0

 

  2.0     

20.0

 

 

 

 

 

 

 

170000   

130000

90000

80000    

70000

60000

50000

40000

 

30000    

20000

20000

20000    

20000

 

 

 

 

13

5  

6

1

0

0

0

0

 

1

6

9

10

12

13

 

 

 

0

 

 

 

 

 

 

 

SELECTED OUTPUT DATA –Resulting Floods at Different Distances

Distance from dam (Km)

Max Elevation(m)

Max. flow cumecs

Hours for Max. Elevation

Max velocity (m/s)

000

41.60

157591

4.000

4.28

10.5

33.31

151616

7.100

2.84

20.5

28.38

146177

10.10

1.65

30.5

23.36

143782

12.4

2.22

40.5

20.25

141588

15.0

1.60

50.5

18.38

138719

16.70

1.40

60.5

16.54

136102

18.30

1.40

70.5

14.05

134039

19.80

1.57

80.5

11.16

132949

21.0

1.63

90.5

8.75

132607

21.600

1.66

15. LAKHS OF PEOPLE LIKELY TO BE KILLED DUE TO A HYPOTHETICAL DAM FAILURE:

An approximate estimate of the inundation areas and the lakhs of people who have to live in perpetual anxiety about the safety of the dam and its likely impacts of collapse and the consequential floods and their catastrophic impacts are presented in the tables below.

 

Table-1:  Population to  live in perpetual terror of Polavaram dam burst and likely to be killed in towns in Godavari delta

 

S.No.

Town

Population

1.

Rajahmundry

4,00,000

2.

Dowlaiswaram

40,000

3.

Mandapeta

50,000

4.

Ramachandrapuram

42,000

5.

Amalapuram

55,000

6.

Kovvuru

40,000

7.

Nidadavolu

45,000

8.

Tanuku

70,000

9.

Bhimavaram

1,45,000

10.

Palakollu

80,000

11.

Narsapur

60,000

12.

Yanam

30,000

 

Total

10,57,000

Table 4 : Population likely to be inundated due to the collapse of Polavaram dam consequent to a maximum credible accident caused by extreme floods, earthquakes, human failures,construction defects,Dam collapses or sudden flood releases from dams in the upstream reaches of the river in other states  etc.

 

S.No.

Areas

Population

1.

Towns & Cities in Godavari Delta

10,57,000

2

Rural mandals of East Godavari

18,92,000

3

Rural Mandals of West Godavari

16,66,000

 

Grand Total

46,15,000

16.  DAM BREAK ANALYSIS  REPORT  PREPARED FOR AP STATE GOVERNMENT BY ROORKEE INSTITUTE EXPERTS:

The authors of the report emphasize that the objective of the report is to do hypothetical dam break flood analysis by preparing 1)input data of the study area compatible to the DAMBRK model, 2) the result in outflow hydrograph at various stations downstream of the dam and 3) the inundation map of the area.  For the dam break flood the worst possible scenario is taken with the failure time as 30 minutes, breach length as 450 meters corresponding to the river width at bed level.  The side slope of the breach is taken as 0.05 which corresponds to the slope of the Godavari river banks at the dam site.  Dam-break occurs here by overtopping when the reservoir water level elevation is 53.32 meters that corresponds with the level at the top of the dam.  The reservoir capacity at the top of the dam is calculated by extrapolation from the area elevation curve of the reservoir.

For the dam-break flood computation and routing NWS DAMBRK programme was used.  Outflow hydrographs were taken for different sites at downstream distance of 6km, 12km, 20km and 30km respectively.  As compared to the outflow peak flood of about one lakh cumecs (35 lakh cusecs) corresponding to passage of hydrograph over the spillway, the hypothetical Polavaram dam break flood reaches a peak discharge of 1.56 lakh cumecs (55 lakh cusecs)at dam site and 1.42 lakh cumecs( 50 lakh cusecs) at  30km downstream of the dam at 0.5hours and 10.7 hour after the dam break respectively.  Hence the peak flood for Polavaram dam failure will be one and half times the corresponding peak flood for no failure case, with the design flood as the inflow flood.  A map with the boundaries of inundated area on both sides of the river banks are presented both for the spillway design flood for no-dam failure case and also for the hypothetical dam break flood of higher intensity.  While the no-dam failure case design flood would pass through the river course and confined within the banks, the high intense flood due to Polavaram dam-break would inundate the lands for about 267sq.kms on the left bank side and 195 sq. kms on the right bank side. 

17. OFFICIALS MISLEAD GOVERNMENTS AND THE PEOPLE ON IMPACTS OF  DAM BREAK ANALYSIS REPORT:

Most of the technical data presented by the  Roorkee Institute in the form of tables, figures and inundation maps have not been presented by the Government in the environmental Impact Assessment report.  It is surprising that the A.P. State authorities inserted virtually a single blank page for presenting information under annexure-VI.3 on the crucial analysis of the downstream flood hydrograph produced by the dam-break of Polavaram and this page is numbered as 186 and the subsequent page numbered 187 starts with the summary of results of sensitivity analysis under annexure 6.4 (contd..) and in between these two page 186 and 187 a lot of important crucial technical data is found missing in the EIA report presented by the A.P. state Government.  Even in the scanty 4 page of information on sensitivity analysis one can notice that the peak flood at the dam site for a dam break scenario is taken at about 55 lakh cusecs with the flood elevation at 40 meters while the floods reach about 50 lakh cusecs in Rajahmundry – Kovvuru region with a flood elevation of 26 meters.  For another case based on higher roughness coefficients and other factors the peak flood due to dam break is taken as 100 lakh cusecs at Polavaram with a flood elevation of 52 meters while the peak flood in the Rajahmundry-Kovvuru region attains a peak value of 75 lakh cusecs with the flood elevation of 34 meters.  Such enormous floods will continue to flow through the river and overtop its banks and inundate thousands of villages and kill several lakhs of people and lakhs of cattle before the devastating floods join the Bay of Bengal.  Paddy fields, garden crops and valuable properties will be destroyed. 

It may be  noticed that the National Institute of Hydrology, Roorkee has not either conducted the flood routing for about 60 to 70 kms downstream of Rajahmundry-Kovvuru region or the relevant crucial data has been omitted from being presented in Environmental Impact Assessment report prepared for the Polavaram dam.  Without these technical details of crucial importance for determining the size of the Polavaram project no meaningful action can be taken by the Union Ministry of Water Resources to make the project safe, economical and people friendly for sustainable development of Andhra Pradesh.

18. INDEPENDENT EXPERTS REPORT ON POLAVARAM DAM BREAK ANALYSIS:

In order to fill this gap independent experts have performed the dam-break analysis for Polavaram dam and presented the flood scenario for all the places downstream of the dam for over a length of 90kms from Polavaram at the dam site to Antarvedi on the beaches of the Bay of Bengal.  For this purpose the same input data that was used by the National Institute of Hydrology, Roorkee was used.  A second check for the results of flooding due to a hypothetical Polavaram dam break was conducted by manual operations by using the fundamental laws of hydrology and hydraulics.  Abstracts of these results are enclosed separately as attachments.

The dam break analysis report prepared at the request of A.P. State Government by the Roorkee based National Institute of Hydrology has clearly indicated that the maximum flood due to the Polavaram dam failure will be 1.5 times the peak flood of  36 lakhs cusecs recorded in 1986 in Godavari.  Moreover this report also considered different dam breach section sizes and also the roughness coefficients and predicted peak flood of about 70 lakh cusecs at Rajahmundry and hence prepared the inundation maps also.  This work done by the Roorkee Institute was continued by using the same data by us and we found that several lakhs of people will be killed due to flash floods arising from catastrophic Polavaram dam failure for several reasons.  The details of the magnitude of the flash floods, their times of arrival, downstream of the dam upto the sea along with the heights of the flood in different regions is presented in the following table.  These values have been also subject to check by manual calculations. 

19. EXTRACTS FROM GULHATI REPORT OF THE KRISHNA GODAVARI COMMISSION SUMMARY AND PRINCIPAL RECOMMENDATIONS (1963)

Para-60: Among the projects referred to in paragraph 58 of the report which impinge or are dependent on one another, the most important are four power projects and five irrigation-cum-power projects in the lower Godavari area, in sub-basins G.9, G-10, G-11 and G-12 proposed by Andhra Pradesh, Madhya Pradesh, Maharashtra and Orissa.

            These projects have a large hydro-electric potential; only an integrated scheme can develop this potential to best advantage.  A regulated supply of water from an upper power project can successively be used on a number of downstream power projects.  The full reservoir levels and tail-race levels at each project site have to be so fixed as to get maximum benefit of the gross head available.

Para-61: A large part of the regulated flow available in the river Godavari from the power projects referred to above, which would amount to much more than 10 MAF., would be surplus to the requirements of projects on the Godavari and can be diverted to the Krishna basin, to the extent these supplies can be utilized in that basin by the following two link canals;

a)      A link canal from the Godavari at Polavaram to Vijayawada at a cost of about Rs.40 crores.  This can transfer usefully about 211 TMC (4.8 MAF) of  water to the Krishna.

b)      A link canal from the Godavari near  Albaka or Singaraddi to Pulichintala on the Krishna at a cost of about Rs.40 crores.  This link canal can transfer usefully about 95 TMC (2.2 MAF) of water to the Krishna.

It may also be possible to make up the shortage in the upper Godvari area, to some extent, by the transfer of about 25 to 30 TMC of water  from the Penganga to the Godavari. The cost of this link canal has not been estimated.

 20. EXTRACTS FROM KHOSLA REPORT OF TECHNICAL COMMITTEE 1953 ON RIVERS KRISHNA-GODAVARI- PENNAR

Appendix-D – Note on the  Diversion of Godavari waters to Krishna basin:

Large tributaries of the river Godavari viz., Pranahita, Indravati and Sabari which meet the river below this dam site(Pochampadu/Sriramsagar location), contribute about 40%, 20% and 10% of the flow reaching Dowlaiswaram.  But unfortunately the Godavari passes on into a ghat section right upto Polavaram or Ramapadasagar dam site.  Any dam built in this reach can only be a power project with very little irrigation potential and o possibility of diversion on account of very high elevations.  The only other site where there is a possibility of diverting supplies from the Godavari  is at Ramapadasagar where a dam or diversion barrage will be necessary for the purpose.  The Ramapadasagar project investigated by Madras visualized the construction of a dam with FRL  +198(1st stage) and storage capacity of 15.9 MAft.  The minimum reservoir level is proposed as +145 and the right canal FSL at head +138.0  With a slope of 1ft in 4 ½ miles throughout its length, the right canal is to cross the Krishna by means of an aqueduct with FSL of +107 to irrigate an area of 4.2 lakhs acres in Guntur uplands.  The total amount of water proposed to be diverted in the Krishna basin under this project is as given below:

Krishna Delta 1st crop – Nil                              :   *7.44 TMC ft.

Krishna Delta 2nd crop – 6.4 lakh acres : 134.81 TMC ft.

Guntur uplands 1st crop – 4.2 acres                   : 105.85 TMC ft.

                                                                        ---------------------

                                                                          248.10 TMC ft.

                                                                        ---------------------

(* This quantity is required for giving early supplies (June1-14) for 1st crop irrigation in

  Krishna delta.)

 

The proposal to take Godavari waters across the Krishna involves construction of an aqueduct which has been roughly estimated to Rs.4.3 crores.  This is likely to be heavily exceeded.  The cost of the canal itself is expected to be Rs.9.91 crores.  The scheme is, therefore, very costly and has been dropped.  This reduces the contribution of Godavari to Krishna area to 142.25 TMC ft. only.

 

If Ramapadasagar dam is not built but a storage reservoir is constructed somewhere upstream either on the Godavari itself or some of its major tributaries and only a  diversion barrage is built at the proposed Ramapadasagar dam site, this quantity will remain unaffected.

 

The total irrigable area in the Krishna delta, is 10.5 lakhs acres and 6.40 lakhs represented 62% of it.  If this percentage is increased to 80 percent which is not desirable in the interest of maintenance of the fertility of the soil, the maximum diversion will be about 184.38 TMC ft.  The economics of this proposal will, however, need to be worked out.

http://profshivajirao.googlepages.com/modifyingsardarsarovardam