Hyderabad: A dam with unique Siphon Technology

Hyderabad: The Saralasagar project is 150 km from Hyderabad and 60 years after it was commissioned continues to be the only one-of-its-kind in India and Asia. The first such project using siphon technology was built in California, USA. 

The Saralasagar project was initiated and built by the Wanaparthy ruler Raja Rameshwara Rao III and named after his mother Sarala. It was completed in 1959 and inaugurated by Jawaharlal Nehru.

Raja Rameshwara Rao III sent his engineer friend P.S. Ramakrishna Raju to California to study the automatic siphon technology. Raju learnt the technology, and returned home and helped build the Saralasagar dam and other projects like the ones at Kinneresani, Pochampad and Nagulapet.

The foundation stone was laid on September 15, 1949, by the then military Governor of Hyderabad, General J.N. Chowdary. The contractor for the project till 1956 was Sripathi Rao. Work on the earth dam had already been initiated, according to assistant engineer Mamilla Buganna, who travels everyday by train from Mahbubnagar to Madanapur to come to Kothapeta, where this beautiful dam exists.

The actual project with the siphon system took off only in 1959. Even then approximately 4,000 acres of agricultural land was brought under irrigation through the Saralasagar project.

Located in Kothakota of Wanaparthy district (part of erstwhile Mahbubnagar district), it is just 6 km from the small and bustling town, filled with small shops. The Saralasagar project is a rain-fed dam and would fill up with water during the monsoon. The water used to flow through siphons into a tiered system, which would eventually flow into the canals and the fields. The Saralasagar itself had a catchment area a 771 acres.

Considering the vagaries of nature, this is no more a holding tank for rain water and now awaits Krishna waters when the Jurala dam overflows. It feeds into the Ramanpaddu project, 12 km from Saralasagar, and the water reaches the old project through a lift irrigation system.

The Saralasagar project is incorporated with a technology which is one-of-its-kind and was very unique for those days and remains so to this day. The siphons have not had any problem since 1959. 

The system is known as the automatic siphon system. There are a total of four priming siphons at a height of 1,089 feet and each siphon has four hoods, with the fourth one having five. Each of these siphons have a three-inch height difference. So, water through each siphon is released in a staggered manner and thus there is no wearing away of the cement by the constant pressure of water. 

It is a masonry construction, a highly durable form, and has not required repairs ever. The priming siphon, as it is called is a tall hollow pipe, with a hood with air turrets. This air acts like suction. When the rain used to fall previously, or the Ramannapada lets out water, it flows into this pipe. As the air comes from the turrets, it forms into an eddy and pushes itself to the top, overflows and falls through a system into water tanks built on the other side.

A total of 4,200 acres are irrigated through water coming out of this system, while the Shankara Samudram has 4,600 acres. The latter takes its water through feeder canals.

The siphon automatically shuts down when the water level goes down. The entire system is ingenuous since it works purely through air suction. In fact there is no need for any person to be around to run it.

Simply put, water from Saralasagar used to be lifted across the dam without being pumped, irrigating 4,182 acres. The total storage capacity of Saralasagar is estimated to be 0.5 tmc, which makes it a minor irrigation project, despite its historical and scientific importance. 

As time passed, building projects became a profitable idea and Jurala and Ramanpadu projects were built, Saralasagar became a mere demonstration tank of how masonry and advanced physics can be used. Now, Saralasagar waits for Jurala to overflow and come to Ramannapadu from where it is released into this project. 

The legendary Rani Shankaramma, who ruled in the 18th century, constructed Shankara Samudram, an irrigation tank which has become a reservoir now. 

For the past 14 years, governments have failed to convert it into a reservoir at Kanayapally. The storage capacity was 1.818 tmc ft, but not even 1 tmc ft has been stored. After the completion of the Bhima-II project, canals from here have been feeding the Kanayapally reservoir and filling it up. Some kind of repair work is happening on this project too.

Experts say spillways are installed to make a passage for the excess water which the reservoir cannot store. The siphon spillway has a closed system in the shape of inverted U. Even with a minor increase in the water level, significant increase is observed in spillway discharge. The release of water does not require any energy or human effort. The structure operates on its own with the help of nature.

Ramakrishna Raju was the expert in the siphon system and, not surprisingly, used it wherever possible. 

The Nagulapet siphon at the village of the same name in Korutla mandal is a special construction which was built to avoid water crossing over. During the construction of the Sriramsagar project, the canal was found to be crossing a canal of the Korutla Vagu, or the Sairam river as it is called. 

Ramakrishna Raju was the one who thought of the underground culvert and it is said that the same siphon system was used. Not surprisingly the project was dedicated to this engineer and named P.S. Ramakrishna Raju Siphon.