Irrigation

‘Big reservoirs an outdated technology’

Print edition : October 28, 2016

T. Hanumanth Rao. Photo: By Special Arrangement

Interview with T. Hanumanth Rao, expert on irrigation and water management.

AT 87, T. Hanumanth Rao is an untiring civil engineer who keeps himself abreast of the latest developments in his area of expertise—irrigation and water management. He retired as Engineer-in-Chief of the Irrigation Department of undivided Andhra Pradesh. In the past 15 years he has been associated with the United Nations as an adviser on projects in over 20 countries.

Hanumanth Rao’s has been the most persuasive and articulate voice against the Telangana government’s redesign of one of the State’s main irrigation projects, the Kaleshwaram Lift Irrigation Scheme. The project proposes to lift about 160 thousand million cubic feet (tmc ft) of water at the confluence of the Godavari and the Pranahita rivers on the border of Telangana and Maharashtra and supply it down south going over much higher ground through central Telangana, and finally almost reaching the capital, Hyderabad.

An intense debate on the efficacy of 18 reservoirs as part of this system and the government’s attempt to circumvent legislation that should kick in when land is acquired for public purposes have led to severe criticism of Chief Minister K. Chandrasekhar Rao’s administration. The land to be acquired runs into tens of thousands of acres, most of it in the Chief Minister’s home district of Medak, and some within his own Assembly constituency, Gajwel. Hanumanth Rao argues that submergence can be entirely avoided if the government is receptive to alternative engineering ideas for irrigation, which he says are already in practice elsewhere, not only in India but in several other parts of the world. Excerpts from his conversation with Frontline:

Why has this controversy come about now and what was the project’s design before 2014?

This project on the Pranahita river was originally proposed to have a barrage at Tummidi-Hetti—they are villages at the confluence of the Wardha and the Wainganga rivers. They are tributaries of the Pranahita, which in turn is a tributary of the Godavari. It is on the border on Maharashtra and Telangana, with half the barrage in Telangana and the other half in Maharashtra. Villages and lands would be submerged in both States if the height of the barrage is 152 metres as proposed by the undivided Andhra State under Chief Minister Y.S. Rajasekhara Reddy’s leadership. Maharashtra objected to this. And now, both States, following the election of the Telangana Rashtra Samiti government, have agreed to a reduced height of 148 m.

Telangana, however, says the water from Tummidihetti will be insufficient if the height is reduced. Therefore, it proposed another barrage at Medigadda downstream of the temple town of Kaleshwaram on the Godavari. Here again, half the barrage would be in Maharashtra.

At Medigadda, sufficient quantity of water is available. They would like to pump all the 160 tmc ft required and take it to Yellampalli, and from there the whole system continues as it is. Yellampalli is a common point for both Medigadda and Tummidihetti.

What would the storage be at Tummidihetti?

Nominal, 2 tmc ft.

At Kaleshwaram or Medigadda?

Seventeen to 19 tmc ft. Storage here is not important. It is the flow which has to be sustained because this is not a reservoir. It is a barrage and therefore storage is only minimal. The Central Water Commission has estimated the available water at Tummidihetti to be only 120 tmc ft, not 160 tmc ft as Telangana had originally estimated. The available number of days is also not enough for the entire cropping period. It is available for only 90 days out of a crop period of 120. This is why Telangana decided to shift the barrage to Medigadda where water is available for 120 days, and 160 tmc ft of water is available. This is 75 per cent dependable water, which means that three out of four years, you are assured of water here.

Water will be pumped from Medigadda through two barrages, one at Annaram and another at Sundilla. These will be used to pump water to the Yellampalli reservoir. Yellampalli is a completed project. Downstream of this reservoir is where the Pranahita joins the Godavari; a little further downstream from there is Medigadda, where the new barrage has been proposed.

With this new project, is there a need for the barrage at Tummidihetti?

It is going to be constructed, but I have made suggestions, nine of them, which I have shared in Telugu with the State government. It is part of a seven-page report, where I explain the need for considering smaller barrages with shorter intervals within the course of the Godavari, reversing its flow during lean season, which could double it up as a navigation course. I have also indicated where reservoirs are required and where they are redundant. For example, Mallanasagar, the reservoir there is not required.

Is it because the displacement and the human cost of Mallanasagar is immense? Or are there sound technical reasons for it as well?

Indeed, there is the human cost. Immense, that’s right. Mallanasagar would be an earthen dam with a height of 62 m, and the bottom width would be about half a kilometre. They [the government] have proposed similar big reservoirs in other areas as well, for example, at Pamulaparthi in Ranga Reddy district. They had initially envisaged a 20 tmc ft reservoir there with 60-metre-high walls, but that has now been reduced to 7 tmc ft. Mallanasagar’s 50 tmc ft is only a part of the 160 tmc ft, which will be stored in the other 17 smaller reservoirs. Baswapur has about 16 tmc ft, Gadhamala has another 10, and you have Anantagiri. But these reservoirs are not required for two reasons. None of them, not only Mallanasagar, none of the 18 is required here. That is because the number of available days of water—120 days, matches the crop days, which are also 120. You have the required water from the source itself for the time period that you are looking for. For irrigation purposes you don’t require reservoirs, it can be pumped directly into the fields. Storage is required when the water is needed year round, and normally that is for drinking and for industries. You require reservoirs with much smaller storage capacities for that.

But the current government seems to have been advised to store the water, which is not done anywhere in the world. Take for example the Jawaharlal Nehru Lift Irrigation Scheme, which irrigates six lakh acres with 38 stages of pumps. It was constructed way back in 1974. The water is pumped into canals, which then distribute the water into the fields. There is no storage anywhere in this scheme which is located in Haryana, about two hours’ drive from Delhi, on the Yamuna.

There is also a Russian example. The erstwhile Soviet Union constructed what is called the Irtysh Karaganda Lift Irrigation project on the Irtysh river. It is considered the biggest in its size and scale. It is in modern-day Kazakhstan. This irrigates 10 lakh acres. We have done it as well. For example at Sriramsagar, where except for the main reservoir all others are canals and distributaries, which flow by gravity. There is a notion that reservoirs are required when there are lifts. This does not always have to be the case.

So what you are saying is that except for the initial diversion structures at the water source, water can simply be supplied through canals and distributaries, even if done through lift irrigation?

Yes. Telangana now wants Tummidihetti barrage to supply water only to Adilabad, but I suggested, because it is available at 50 m above Medigadda, take advantage of it and reduce the pumping cost. I suggested the water to be taken from Tummidihetti to Yellampalli directly by gravity through Sundilla, which is at a 134-m level; it will come by gravity from 140 m. From Sundilla to Yellampalli, the water could be pumped, for which the infrastructure is being constructed. This will also save a 50-m head. My nine suggestions are on reducing the cost without sacrificing the benefits.

Why do we need this barrage at Tummidihetti when the water that is required is available at Medigadda?

So as to avoid pumping water from Medigadda to Sundilla for 90 days, reducing the requirement for only 30 days, as 120 tmc ft of water is available at Tummidihetti for the rest of the time.

Why two barrages at such a short distance?

Medigadda is at a level of 100 m, from here they have proposed a pumping station to pump water to Annaram barrage, which is a costly proposal, and the height to be pumped is 49 m. It is costly because 10 pumpsets have to work with pipelines of 5 m in diameter. They have to be placed at a pump house. Imagine the size of it. That is needed for pumping into Annaram barrage, and then the water will be pumped to Sundilla with a lift of 10 m, that is from 124 to 134. One of my suggestions was to avoid this pump house altogether, which could save us up to Rs.3,000 crore. Have barrages between Medigadda to Yellampalli at a distance of 112 m above sea level, that is 100 to 112, 112 to 124, having pumpsets within the barrage itself called power blocks. The barrage will have a power block and a spillway. The idea is to use the river’s natural course in the reverse direction. Therefore, if there is excess water available at the upstream course, the Yellampalli reservoir will overflow. When this happens, the pumpsets will be used as turbines to generate power, that is, we would be introducing what are called reversible pumpsets, which are currently in use at the Nagarjuna dam on the Krishna river.

We don’t see the pump houses outside the dam structure. It is within the dam, and when there is excess water it is let out through the spillway, but before that they generate power by turning the turbines placed between the dam’s walls. And if the water has to be pumped up, these will work as pumpsets. Like that, we can take advantage, by producing power when the water is in excess flow in the Godavari.

Which means the barrage would be a huge structure?

Quite right. It would also be the length of the river, which is about 1.5 km. It would be a stand-alone structure. But the government’s engineers who met me have raised doubts about the possibility of pumping water with such low-head barrages, that is to say, with only the length of 12 m. They say reversible pumpsets are not available in the market to pump water for such low vertical lifts. According to them, pumps are available only for greater heights, such as 50 m. But that is old technology. They are not abreast of the latest technology. They consider the manufacturer’s marketing pitch as final. I have advised them to consult with the R & D Department of BHEL. Technology-wise it is possible, and the technology is there, and I know that BHEL is abreast of it as well.

Would it not be more cost-effective to use the higher lift pumpsets of 50 m to avoid construction of additional barrages?

Well, there would be greater submergence in that case. When the height increases, the lands and villages around the river get submerged. What I have suggested would be within the river’s course. This would be well within what we call the flood zone.

Another thing is, there will be a lock for every barrage, and ships could sail through these locks, thereby making the river a navigation canal, because a minimum depth of 4 m could be maintained. This is required for ships to ply. Therefore, even in the summer, big, ocean-going vessels can ply on the river, the way it is being done on the Saint Lawrence river on the United States/Canada border, which connects the Atlantic Ocean to the Great Lakes—Lakes Superior, Michigan, Erie, and so on. All these lakes are connected already; and they are further connected at Lake Ontario to the sea through the St. Lawrence river. That river has been made navigable for seagoing vessels by constructing seven barrages. I want to make the Godavari river similarly navigable for seagoing vessels so that transport costs get cut down considerably. For this we have to construct 13 barrages on the Godavari. Similarly, the Manjira and the Wainganga could also be made navigable.

In fact, Mr Nitin Gadkari [Union Inland Waterways Minister] issued a statement recently where he mentioned that he intends to make the Manjira navigable, which means the Central government will bear all the cost. If you have to make it navigable, the minimum depth has to be maintained to the extent of 4 m, which is possible when you construct barrages. Otherwise, you will have to build a huge reservoir like the Three Gorges dam [on the Yangtze in China], which will submerge a long stretch of land. This could be avoided if we build around 30 barrages all along, which would include the Manjira river. We could have another four barrages on the Pranahita river to produce power, that is, between Tummidihetti and Kaleshwaram, where there is a 50-m fall. Four barrages with 12-m heads could be constructed. Twin purposes could be served this way, which is to produce power and to make the river navigable. Mr Gadkari’s statement included barrage construction on the Wainganga in the latest proposal. His Ministry’s budget is Rs.1 lakh crore this year.

Looks like this could turn out to be more expensive than the one that the Telangana government has proposed?

No, no. This is very cost-effective. The cost would only be to turn the impeller into turbine. Impeller is a pumpset. That will become a turbine blade. That’s the only manufacturing modification which is required, because the generator is the same. It would work either as a motor or as a generator. I have given all this information to the government, including the company’s name, which makes the 4- to 15-m reversible pump motors.

Is this not a technology that BHEL can replicate?

Yeah, sure! This is the latest technology, and our people should be well acquainted with it.

So how cost-effective will it be if we go by your advice?

We save Rs.30,000 crore out of this entire project! I am not dismissing the need for reservoirs on canals entirely. We do need them in certain cases. For example, at the Palamuru Ranga Reddy Lift Irrigation project [in Mahbubnagar district], you do require a reservoir.

Why is that?

That is because the availability of water at the source is for 60 days, while the crop period is 120 days. Therefore, in order to supply water for 120 days, we will have to draw water in those 60 days and store it somewhere for another 60 days. The storage required is of the order of 60 tmc ft. I have added other requirements, such as industrial and domestic use, increasing it to 75 tmc ft. Therefore, there it is needed. This is the cardinal principle to be used to decide the need for a reservoir.

The government’s own proposal is in consonance with my suggestion as far as the Yellampalli reservoir is concerned. The only modification I have made is to have low-head barrages to make the river’s course navigable and for it to serve the twin purposes of producing electricity as well while at the same time avoiding submergence. Now coming to Yellampalli and below—of the 18 reservoirs which have been proposed, Mallanasagar is 535 m and Pamulaparthi, that is Kondapochamma, is 624 m. Now to pump water up to 535 m, and then take it to SRSP [Sriramsagar Project], which is at 300 m, involves an unnecessary pumping of 250 m. Why take to a higher height and then allow it to flow by gravity, because taking it to a higher height you spend money. I have suggested using the river’s course in the reverse and pump up another 150 m, as opposed to 400 m.

Do you say that the entire Yellampalli and all the projects further down south could be avoided?

I am not saying that. Those canals/lifts have to be constructed. Those areas have to be irrigated. What are not required are the reservoirs. The water could be directly pumped into the fields from main canals and branch canals. The water will have to be pumped given the elevation, and it will have to go through various stages.

Let me take the example of the Jawaharlal Nehru Lift Irrigation scheme on the Yamuna in Haryana again. At every point the water is lifted, there will be a command area [the estimated area under irrigation]. This project is also on an incline. Therefore, this could be done from Yellampalli down south for the entire cropping period, without storing the water. There are no reservoirs in the entire six lakh acres that is irrigated in Haryana.

But the government says these reservoirs would be required for future needs, for example, when a second cropping season is considered. Do you think this then justifies the reservoirs?

This is being put forth as an afterthought now; it cannot be argued and left there. It has to be done so with a project report and that argument has to be complied with. It could be given as an explanation, but then the project’s size rises dramatically for a two-crop water requirement. And none of the project reports the government has shared with me so far has suggested this point, which is why I think this is just being used as an argument now, when the government has faced severe criticism, to justify its design.

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