Our gabions and Reno Mattresses provided advanced and flexible flood protection downstream of the Joshiyara Barrage, in Uttarkashi, Uttarakhand
The opening of the Joshiyara barrage gates caused rapid flow fluctuations in the flow of river Alakananda, leading to erosion of the left afflux bund and its slope. The height of bund was also considerably reduced, resulting in the inundation of the nearby countryside downstream of the barrage. To address this issue, we came up with advanced and flexible solutions to protect the bund and prevent flooding of the adjacent countryside.
The Joshiyara Barrage is located on the river Alaknanda, in Uttarkashi, state of Uttarakhand. The barrage is designed to divert water into a headrace tunnel to generate electricity at Dharasu Power Station.
The opening of the barrage gates caused rapid flow fluctuations and turbulence, disturbing the entire stone pitching over the left afflux bund and leading to erosion.
The height of the bund was also an issue as it was too low to protect the nearby areas from flooding in Highest Flood Level (HFL) conditions.
The main purpose was to provide a permanent and flexible solution which can easily withstand the rapid flow fluctuations and can counter the flooding of nearby areas in high flood conditions.
The solution system provided was intended to
- Prevent erosion,
- prevent scouring and instability of the toe of the structure,
- protect the nearby areas from flooding.
The toe instability was prevented by constructing a gabion wall over the existing reinforced cement concrete (RCC) toe wall. Reno Mattresses were added over the gabion wall for surficial protection. Reno Mattresses were also installed below the gabion wall and in front of the RCC toe wall for protection against scouring at toe for the river side. A similar pattern was adopted also for the countryside facing of the bund.
This solution allowed to considerably increase height of the bund up to the required HFL with safe free board for prevention against flooding of the adjoining countryside areas.
After completion of the work, the intended purposes were met. The gabion wall and Reno Mattresses withstood the flow fluctuations and made the bund structurally more viable and stable.
For more information, please download our case history.