Manjira Dam In Serious Trouble, Needs Urgent Attention
State dam safety panel flags alarming neglect, structural cracks, and overgrowth that threaten long-term stability of Hyderabad’s key drinking water source.
Hyderabad: The Manjira dam, one of Hyderabad’s drinking water supply lifelines and which supplies up to 100 million gallons of water a day, needs urgent repairs, and its long-term safety may be compromised if the dam does not receive the required immediate attention, an internal report of the Telangana irrigation department has said.
The report by the State Dam Safety Organisation (SDSO) described some of the maintenance aspects of the dam as ‘alarming’ with its earthen bund getting weakened by unchecked growth of acacia trees, its gates in a state of serious disrepair, and even portions of its spillway seriously damaged due to neglect of maintenance over the years.
Incidentally, the Manjira dam too has suffered downstream spillway damages on account of shooting flows that have not only resulted in damages to the apron, but also uprooted portions of it. The damages are not dissimilar to the one that caused damages to the downstream aprons and stilling basins of the Medigadda, Annaram, and Sundilla barrages of the Kaleshwaram Lift Irrigation Scheme (KLIS). Large-scale pitting of the concrete in the fixed apron was seen, while the flexible apron “is like a sitting duck” for damages, the report said.
“It must be clearly understood that shooting flows would continue to cause damages here and there and need to be repaired as and when they occur. If not attended, the scours would work backward to the dam and threaten (its) safety,” the report said, highlighting years of neglect of the dam’s maintenance.
It further said that currently, the practice is to open “certain conveniences selected against the standard practice’ and this procedure must be “dispensed immediately as the same is causing damages at select locations,” of the dam’s structure.
In their report submitted to the irrigation department this March, a panel of experts and SDSO officials, after a detailed inspection of the dam, also found that though the dam appears sturdy from a distance, shear cracks were discovered in the dam’s piers.
These, the report said, indicated yielding of the piers to “distress that has occurred beyond their bearable limit.” The experts attributed this to the pressure on the dam to store water round the year to supply drinking water to Hyderabad.
“Masonry structures,” as in the case of the Manjira dam, “cannot bear tensile stresses like steel reinforced structures.” And since the dam is used as a drinking water source, “such indications of structural anomalies should be taken seriously,” the report said.
Another issue highlighted by the dam safety team was the unchecked growth of acacia trees on the earthen bund. “The dam is in a seriously ruined condition”, the report pointed out, calling the tree growth a “scrub and heavy jungle,” and the conditions were such that 1.5 km of the dam’s bund could not be inspected as a result.
Such growth can lead to “irretrievable distortions” leading to massive undulations in the dam section and its revetment, and these distortions can be seen throughout the length of the earthen dam of the barrage, the report added.
