BENGALURU: As most of the reservoirs in Karnataka near full this month, which is the middle of monsoon, state government agencies along with experts are now working to take up silt studies at all reservoirs.
The study will not only help in planning projects better, but also aid in taking measures to ensure dam safety, improve water holding capacity and prevent flooding. As per data from the Karnataka State National Disaster Monitoring Centre (KSNDMC), the storage level in the Cauvey basin is 94%, Krishna basin 80% and Vani Vilas Sagar 59%. The overall storage level across all the reservoirs is 77% as on July 27.
“This is not the first time that the reservoirs have hit a good level in July. In 2018-19, when there were severe floods, the reservoir levels were nearly full. Similar was the case in 2021 and 2022. Only last year, when the state faced a severe drought, the reservoirs were not full, but were managed at 56%. Now since the monsoon is good, the water runoff too is good. The soil test is being conducted after 5-6 years. The study report from the Cauvery basin will also be shared with the Cauvery Tribunal,” a senior official in the Water Resources Department (WRD) told The New Sunday Express.
The permitted national silt accumulation level for reservoirs is 3%. As per the last study report in the Cauvery basin, it was 2% and in Krishna basin it was just a fraction less than 3%. The highest silt accumulation is at the Tungabhadra reservoir, where water holding capacity has dropped from 135 tmcft to 105 tmcft.
“Silt studies are best conducted when the reservoirs are full or near full and rain is good. They are done using mathematical methods and sonography technology. Now with heavy rainfall across the state, dam stress levels rising and encroachments around reservoirs and catchment areas increasing, it is crucial to ascertain silt levels and maintain water levels. We are also ensuring that the dams are not full to their optimum level as it could impact the structure and lead to floods. We are trying to keep the levels to less than 70%. The dams will be filled to the brim only by August-end, when monsoon starts waning,” the official explained.
According to the India Meteorological Department (IMD), Karnataka has received 28% excess rainfall between June 1 and July 27. Against the normal forecast of 421.8 mm, the state has received 541.9mm rainfall for the period.
Strong wind alert
The India Meteorological Department (IMD) has issued a strong wind alert across the state and advised people, especially fishermen, to exercise caution. As per its forecast, wind speed of 50-60 kmph will prevail. In Bengaluru, the highest wind speed of 52 kmph was recorded at 2.05 pm on July 20 and at 3.20 pm on July 25.
Rainfall
Coastal Karnataka recorded 29% excess rainfall. Against the norm of 1827.2mm, the region recorded 2361.8mm. North-interior Karnataka received 26%. Against the norm of 206.4mm, it recorded 260.5mm. South-interior Karnataka recorded 29%.Against the norm of 324.2mm, it saw 419.5mm.