The construction of a barrage across the Kollidam River, between Adhanur and Kumaramangalam villages in Cuddalore and Nagapattinam districts, to store flood water, has gained momentum. The construction work, being undertaken at an estimate of ₹494.84 crore, began in May 2019.
The barrage aims at storing nearly 1.02 thousand million cubic feet (tmcft) of water that usually drains into the sea, which in turn will help recharge the groundwater table in villages in and around Adhanur and Kumaramangalam in the two districts besides ensuring stabilisation of the existing Ayacut.
The flood-water harnessed in the barrage will ensure additional supply of water during scarce times to North Rajan channel in Cuddalore and South Rajan channel in Nagapattinam district.
According to A. Kannan, Executive Engineer, Public Works Department (Special Buildings Division), “About 25 % of work has been completed so far. The barrage comprises of as many as 87 bridge piers that will come up on 19 rafts between the two villages. As far as raising of rafts along the proposed stretch is concerned, the concrete work on the first raft has already been completed. Work on raising four piers on the first raft is now underway. Each pier has a width of four metres,” he said.
The construction of a diaphragm wall is the other major work being undertaken at the project site. It is aimed at preventing seepage of water and arresting the movement of sand in the vicinity of the structure.
Out of the total length of 1,064 metres, the upstream cut off wall and downstream cut off wall have been completed for a length of 284 metres. The PWD has planned to complete a major portion of the work before the monsoon. It has been proposed to construct 19 rafts before July, Mr. Kannan said.
The proposed barrage will have 84 vends with a capacity to discharge 4,55,726 cusecs. The capacity of the barrage is 0.334 tmc and around 1.072 tmc of surplus water is proposed to be harnessed through four fillings of rain and surplus flows in a year, once the structure is completed. The barrage will benefit as many as 5,427 hectares of land each in Cuddalore and Nagapattinam districts.
PWD officials estimate that as many as 307 borewells in 12 villages in the two districts will be recharged, which will help in recharging the ground water table in the surrounding villages. Each bore well is expected to irrigate an average of 14 acres each covering 1129 hectares in Cuddalore district and 657 hectares in Nagapattinam district.
It has also been proposed to construct two new sluices to control the flow of water into the North Rajan and South Rajan channels. The barrage will also have a two-way bridge at an estimate of ₹26 crore connecting Adhanur and Kumaramangalam villages.
The single-lane bridge in Anaikarai is dilapidated and the proposed bridge is expected to ease the traffic flow between the two districts. The banks of the Kollidam River will also be strengthened on both sides of the barrage site. The project is expected to be completed by 2021, a PWD official said.