shivajirao

POLAVARAM PROJECT WITHOUT SUBMERSION – INLAND WATER NAVIGATION OF SEA GOING VESSELS
bhadrachalam temple areas under floods in 1986.
http://wikimapia.org/2084925/Bhadrachala-Sita-Rama-Chandra-Swamy-Kalyana-Mandapam#/photo/1729695[ 1986 floods in temple of bhadrachalam]

(Proposals first appeared in Eenadu 5-1-2008)

T.HANUMANTHA RAO

Former Engineer-in-Chief, Government of Andhra Pradesh and

United Nations (OPS) consultant

Introduction: The recent peak flood, that occurred during the first week of October 2009, in the river Krishna has given a clear indication of what the maximum peak discharges in the Indian rivers would be in the future. Though the effects of global warming are not clearly established in physical terms, scientists (after analyzing the existing data) had concluded that the peak flood discharges in the Indian Peninsular rivers, Krishna and Godavari would be increasing in the future. The peak flood flow in Krishna river on 3-10-2009, is reported to be 25.5 lakh cusecs and this is nearly 2.5 times than the peak flood of 10.6 lakh cusecs ever occurred in the past 100 years. If the same phenomenon is predicted to the Godavari river at Polavaram Dam, certain startling issues would emerge. The maximum flood discharge ever occurred in Godavari river during the past 100 years, was 33 lakh cusecs and the Polavaram Dam was designed for 36 lakh cusecs. The Central Water Commission had determined the Possible Maximum Flood (PMF) as 50 lakh cusecs and the dam spillway was redesigned accordingly. The recent floods in the Krishna river had created a scare in the minds of engineers and policy makers as to what would happen to Polavaram earthen (rockfill) Dam if such a 2.5 times increase in flood flow, namely 83 lakh cusecs occurs in the Godavari river. The dam break analysis done by the National Institute of Hydrology (NIH) from Polavaram to Rajahmundry and by other scientists from Rajahmundry to the sea, indicated that when a peak flood of 50 lakh cusecs occurs in the river and the dam breaks, Rajahmundry area would be under 40 feet of water. This would lead to the death of 46.15 lakh people (2001 census) in the Godavari Delta. Such a global tragedy in waiting, should be avoided at all costs. The 2.5 times increase in Krishna floods at Srisailam, has resulted only in a few hundred deaths, whereas the same increase in Godavari floods at Polavaram would result in a major catastrophe of a gigantic scale Now a question arises – is it not possible to avoid all these risks and yet realize the same benefits of the Polavaram Dam through suitable technical alternatives, which do not result in huge submersions of villages, agriculture lands, forests etc. Fortunately the answer is yes, in the case of Polavaram Dam. A study of latest thinking in the world on this subject would be relevant.
Big storage: The consensus of opinion evolved during the past decade of various international for a (including the World Water Forum), where engineers, environmentalists, social scientists and economists meet, favoured the entire river length to be developed as a continuous series of stepped reservoirs, limiting the water submersion tos the peak flood flow section of the river. Big storage reservoirs will have to be considred, only in special cases, such as flood storage (to prevent serious damages) carry over storages to meet drinking water requirements during drought years, and special hydro electric locations where adverse environmental impacts would be a maximum Live storage in Polavaram Dam is 75 TMC, but it submerges 293 villages, over 1 lakh acres land 3731 hectares of forest land all resulting in displacing about 1.6 lakh people. All these can be avoided if a barrage is constructed in place of the dam. Let us examine how the barrage proposal an give all the benefits envisaged in the dam proposal. It has to be understood that this alternative is suggested only for the dam and not the project as such. In fact this barrage proposal aims at increasing the benefits of the project without causing submersion of villages. There is no doubt that Polavaram Project is very much needed for the development of all the regions in Andhra Pradesh.
Details of barrage: The barrage suggested in place of Polavaram Dam would be similar to the one existing at Dowlaiswaram across the Godavari river. It would be designed in such a manner that the upstream water level at the barrage will be the same, as the water level on downstream of the barrage, irrespective of the flood discharge – whether it is 20 lakh cusecs or 33 lakh cusecs or 50 lakh cusecs. The vent way of gates of barrage will be increased to correspond to the river flow cross section area during the maximum flood, by extending its length into the flanks and providing smooth approaches and the whole process will be determined by hydraulic model studies. In other words the ‘afflux’ would be limited to near zero, for all river discharges, eliminating the need for flood banks on the upstream side of barrage. It is reported that a water level o 100ft above MSL was recorded at Polavaram, during 1986 when the recorded maximum flood at Dowlaiswaram was 33 lakh cusecs; This water level will not get increased to a higher level even though the barrage is constructed. Whatever natural submersion that will occur for a river discharge of either 33 lakh cusecs flow or 50 lakh cusecs flow will continue to occur and will not get increased even after the barrage is constructed. In other words, there will be no additional submersion due to the barrage, and the entire flow will be limited to the high flood zone section of the river. Some tribals have occupied certain places in the high flood zone area and are now residing there. During high floods, they would vacate their houses and move to the higher areas, and again get back within a few hours or days when once the floods recede. But when the barrage is constructed, the high flood zone will be filled with water for a few months and hence they will have to be rehabilitated. The cost of this relief and rehabilitation will be negligibly small. In this proposal, there is no question of submersion of the 293 villages, forest areas, lands etc as in the dam proposal, and hence the construction of protective dyke walls in Orissa and Chattisgarh does not arise. Salient features of the barrage are briefly explained.
Salient Features:

Upstream and downstream water levels with 33 lakhs cusecs = 100ft (30.48m) above MSL.
Sill level of spillway gates = 40ft (14m) i.e. bed level of river.
Height of spillway gates +54ft (16.5m)
Top level of gates = 100 ft (30.48m)
Top level of bridge on spillway = 3m free board from water level when 50 lakh cusecs flood flows through the gates.
Maximum Observed Flood in 100 years = 33 lakh cusecs
Possible Maximum Flood (PMF) = 50 lakhcusecs. Provision is made in the design of gates for PMF exceeding 50 lakh cusecs also.
Storage in barrage upto top level of gates = 30 TMC
Ayacut: 2,50,000 acres. Originally 7,20,000 acres ayacut was contemplated. But, this got reduced to 2,50,000 acres due to the actual availability at site. As per the studies conducted by scientists of an International Organization (WWF), it was revealed that more than 4,70,000 acres within the ayacut area of the project, is already under irrigation through a) several major lift irrigation projects about to be completed, (e.g. Tatipudi, Pushkaram, Chagalnadu), b) Minor irrigation tanks completed (c ) private ground water tube/dug wells d) public tube well projects built by the State Irrigation Department Corporation, etc. To think that the ayacut under Polavaram project would still be 7,20,000 acres is a myth and it would therefore be wrong to proceed on this basis.
Canals: Gravity flow canals with FSL at 95ft an be planned on either side of the barrage. But this would involve in excavation of new canals. New gravity canals would need additional land acquisitions and capital costs over and above the amount of about Rs.2000 crores already spent on the two canals. Though it is technically possible to divert 80 TMC from Godavari to Krishna river at point just upstream of Prakasam Barrage (as against Budameru through the left canal under construction) it may ultimately be economical to use the canals now under construction, rather then excavating new gravity canals. In such a case water will have to be lifted from 95ft level in the river to 133ft level of the annals. For a discharge of 12,00 cusecs (required for 2.5lakh acres, diversion of 80 TMC water to river Krishna etc.) and a static head of 38ft. (11.6 m) it would require 54MW and this can be met out of the 350MW hydro power that would be generated in the barrage.
Hydropower: The Central Electricity Authority was holding a view that it would be possible to generate about 720MW hydropower in Polavaram dam as against 960MW proposed by the State Government. On account of constructing a barrage (instead of the dam), the hydro power component, would get reduced to 360 MW. However, this can be improved to 1260 MW by constructing three barrages on the upstream side – one near Bhadrachalam, second near Kunavaram on the Godavari river and the Third across the Sabari river. All these barrages will have submersions within the high flood zone of the river and no village/forest/lands will get submerged. Thus, 540 MW more hydro power can be generated through these 4 barrages proposed, as alternative to the Polavaram dam.
Water Requirements: Polavaram dam envisages a live storage of 75 TMC and for the sake of this, a huge submersion problem is being faced. Incidentally, this live storage gets filled up in 8.5 hrs when the flood is 25 lakh cusecs. Since the ayacut area got reduced from 7.2 lakh acres to 2.5 lakh acres, there is no need to have any storage for the Polavaram project. Just as the run of the river system at Dowlaiswaram is able to supply water for more than 10 lakh acres, the alternative barrage at Polavaram can easily irrigate 2.5 lakh acres as a run of the river system. This is possible because, the cropping pattern is only for one crop and that too in the Kharif rainy season when there will be adequate flows in the river. All other benefits that are envisaged in the Polavaram dam proposal can still be achieved through this barrage proposal. For example the inter basin transfer of Godavari water to river Krishna to an extent of 80 TMC can be drawn during the rainy period of four months when there will be adequate flows in Godavari. Drinking water and industrial water requirements throughout the year (24 TMC) can be met with, through the 30 TMC storage available in the barrage. If for any reason at a later date, storage of water is needed for the project an utilizable storage of 80 TMC would still be available in these four barrages as against the urilizable live storage of 75 TMC in the Polavaram Dam. The only main difference in the barrage proposal is that water has to be lifted from the barrage to canals over a static head of 11.6M The same canals can also be utilized for carrying additional discharges (during the rainy season) to meet the requirements of further lift irrigation projects (Uttara Kosta Sujala Sravathi) on the left and right main canals. In such a case additional pumping units will have to be installed in future, at the barrage site, to pump this additional water for a static head of 11.6m.

Costs: The latest estimated cost of Polavaram Dam (without canals) is stated to be as 16,500 crores, out of which Rs.10,000 crores would be for spillway, rock fill dam and Hydropower civil works plus Rs.6,500 crores for Relief & Rehabilitation (R&R) of displaced persons. On the basis of the recent estimate for the barrage at Kantalapalli on Godavari river (Rs.880 crores) the cost of the above mentioned four barrages can be estimated as Rs.6000 including the capital cost of pumping at Polavaram barrage. Thus the alternative proposal would lead to a saving of about Rs.10,500 crores apart from having the facility of quick execution and completion of the project much earlier than the Dam proposal. Added to this there will be no interstate or submersion problems. More importantly there is no risk of “dam break” of the earthen (rock fill ) dam threatening the lives of 46,15,000 people, which cannot be ruled out as a figment of imagination in the light of recent floods in Krishna river (when 2.5 times the maximum flood occurred). When all the benefits of Polavaram Dam project could be achieved through the barrages at less than one third of the cost and without submersions it requires a revised thinking on this project, especially in the revised context of the magnitude of the peak floods.
Interstate problems: The barrages proposal will have no interstate problems with Orissa and Chattisgarh states, as there will be no submersion in those states when the alternative barrage proposal is implemented. If the past experience with the Orissa state regarding Vamsadhara stage II and Janjhavati dam is any guide (stalling the projects for over 2 decades), it will not be prudent to assume that they will allow construction of Polavaram dam since it involves submersion of about 20 villages in their states.
Inland water navigation for seagoing vessels: The entire length of Godavari river will have to be converted into a series of continuous stepped reservoirs, one below the other by constructing a number of barrages, all along the rive. The author termed this as “Step Ladder Technology” about a decade back. Sufficient draft (depth of water) will be maintained all along the river, even in summer, to facilitate sea going vessels (ships upto 3000T capacity) to ply in the river. This would be similar to St.Laurence river seaway (7 barrages), Tennessee (9 barrages) river Illinois (9 barrages), Missouri (10 barrages) and Mississippi river (27 barrages) in USA. The entire Godavari river will be a storage reservoir with submersions limited to the high flood zone of the river. A ship load of coal from Singareni can go to any Indian seaport like Tuticorin, Haldia, Mumbai etc and also directly to any other foreign country. This is also called as Green Technology. Similarly ships from other countries can ply in the Godavari river and reach any place all along the river. Villages and towns along the river will get international connectivity as happened in the cases of US, Europe(Rhine-Danube linkage) and China (from the Pacific sea to Chungking through the 3 Gorges dam). This will facilitate development of major and minor industries duly utilizing the mineral and human resources in the area. Employment throughout the year is possible through navigation, Industries including mass mineral based units (e.g. coal, cement). Water required for these units as well as hydropower can be made available to these units. Any raw materials imported can be done at a cheap transport cost. Likewise goods (including manufactured goods) can be transported to other places (including international) at a cheap transport cost. Ultimately Andhra Pradesh can develop economically like parts of China, withstanding international competition by producing goods at competitive rates. More important is the employment generation to the youth in this navigation and allied sectors and the disposable incomes generated, boosting the economy of the area, (through several chain reactions of development). The economic development of US and Europe in the mid Twentieth Century can be attributed to this navigation associated sectors, where nearly 70% of the workforce is employed, whereas only 15% of work force was employed in the agriculture and irrigation sectors. Through Irrigation is important for food security, many people still think that eradication of poverty can be done by irrigating every acre of arable land. All the irrigation projects in Andhra Pradesh are being executed for raising one assured irrigated crop during the rainy season. This will give employment to the landless labour for about 90 days in a year. They will have to go out to seek employment for the balance 9 months in a year. This is the reason why poverty still continues among the landless labour (who constitute 50% of rural population) in the Krishna and Godavari deltas inspite of every acre in that area being irrigated.

In the case of Godavari river, inland water navigation for sea going vessels can be made possible through construction of 11 barrages as shown in the map in the vicinities of 1. Pedda Bellala, 2. Yellampalli, 3. Chinnur, 4 Suraram, 5. Kantalapalli, 6. Edira, 7. Dummagudem, 8. Bhadrachalam, 9. Koonavaram, 10. Sabari and 11. Polavaram. Out of this the items 2, 5 and 7 are now under construction. Items 8, 9, 10 and 11 will form part of Polavaram Dam alternative plan as described above, under the para 5 ‘Costs’. Thus there will be a need to construct additionally four barrages (items 1,3,4 and 6). There may also be a need for a few more barrages for navigation and this can be determined after a detailed investigation. The cost of the above 4 additional barrages, locks and hydropower (about Rs.6,000 crores) can be met out of the savings of Rs.10,500 crores (as mentioned above in para 5 ‘Costs’). Grants available in the Inland Water Navigation sector in Government of India, can also be utilized for this navigation requirement as well as other works such as developing inland water ports, rail and road connectivity to such ports, construction of wharfs, godowns, warehouses, purchase of loading and unloading equipment (cranes) extensionof power lines etc. Also there is a possibility by considering all the above development project as a “National Project”. This is the stage when Andhra Pradesh will have to plan for total economic development all along the Godavari basin, revolving round the water sector, rather than limiting all the development only to one irrigation sector.

POLAVARAM BARRAGE (ALTERNATIVE TO DAM)

Design details

1. Discharges in canals (left & right) in Kharif season:-

(a) Ayacut (Total) = 2.5 lakh acres @ a duty of 75 ac/cusec

Discharge = 2,50,000/75 = 3333 cusecs

(b) Krishna diversion in 120 days = 80 TMC

Q in 1 day = 80/120 = 2/3 TMC

@ 1 TMC / day discharge = 11,574 c/s

2/3 /day discharge = 11,574 x 2/3 = 7,716 cusecs

(c ) Domestic & Industrial water

365 days = 24 TMC

1 day = 24/365 Q = 24/365 x 11574 = 761 cusecs

Therefore Total discharges in both the canals = a+b+c = 11810 cusecs

Or 11810/35.316 = 334.5 cumecs

(Note : During non Kharif season, there will be pumping only for item (c ) requirement)

2. HP of pump sets required for both left andright canals: FSL Left canal =40.54 m

Water level in barrage (allowing 1.0 m lower level) = 29.48;

Therefore Static head = 11.06m

Adding frictional losses @ 10% = 1.10, Total head = 12.16m

HP = 334.5 x 1000 x 12.16 x 100 ( eff. Of motor 95% x ef. pump

75 76 80% = 76%

= 71,360 HP or 71360 x 0.746 = 53235 KW or 54 MW

3.Four additional balancing reservoirs can be constructed infuture, on each, on Pampa, Thandavar, Varaha and Sarada rivers to store about 24 TMC for future domestic and industrial uses. These reservoirs can be fed through the left canal by pumping additional discharges (as part of a future project).