Surat: Heavy rainfall across parts of central India and the Tapi river catchment has triggered a sharp surge in inflows into the river system, sending a huge volume of water into the Ukai reservoir. The dam’s water level rose by nearly 17 ft in just three days, bringing it close to its seasonal rule level.On Friday, the water level at Ukai was 316.51 ft, with around 2,633 million cubic metres (MCM) of water stored in the reservoir. By Monday, the level had risen to 333.37 ft, while storage increased to 4,791 MCM. This means the reservoir received about 2,158 MCM of water in just three days.The sudden increase in inflow has been driven by intense monsoon spells across the catchment, adding pressure on reservoirs upstream of Ukai, several of which have already reached their maximum storage levels prescribed under their rule curves.The rapid rise in Ukai’s water level is being closely monitored, particularly with more than a month of the monsoon season still remaining. The issue is significant for Surat as a sudden release of a large volume of water from Ukai was a major factor behind the devastating floods in the city in 2006.Officials and experts said reservoirs in the upper Tapi basin had accumulated substantial water during the early phase of the monsoon. With several reservoirs now at or near the prescribed seasonal levels, dam authorities have been releasing water to keep them within safe operating limits while making room for additional runoff from fresh rainfall.Hydrology experts said monitoring systems across the Tapi basin have improved significantly. Gauge stations in the catchment help authorities estimate the volume of water likely to reach Ukai, particularly during intense rainfall in the intermediate catchment between reservoirs in Maharashtra and Ukai. Earlier, the volume of runoff from this stretch was difficult to assess in real time.“The rain and such a huge inflow can become a cause of concern if not monitored properly. There is a need for close monitoring when the water level is fast approaching the rule level,” said P L Patel, director, VNIT Nagpur.Patel, a former professor at SVNIT who has studied rivers and hydrology in several regions, said accurate and timely inflow estimates were crucial for planning dam releases and maintaining safe reservoir levels. He also cautioned against the impact of short-duration, high-intensity rainfall, when the catchment’s ability to absorb or temporarily store water is overwhelmed, resulting in rapid runoff downstream.Experts also pointed to sedimentation as a growing concern. The gradual accumulation of silt reduces a reservoir’s effective storage capacity, meaning water levels can rise faster for the same volume of inflow, increasing the need for timely operational decisions.“A huge quantity of water has reached Ukai in the last three days and the dam has played a key role in preventing a flood-like situation downstream. This much rain and inflow is a pattern observed in recent years and has become regular now,” said PV Timbadiya, professor, SVNIT
