Chennai’s drinking-water reservoirs have begun receiving marginal inflows after nearly three months of limited recharge, but officials have cautioned that sustained heavy rainfall will be needed to significantly improve storage levels. The development follows the onset of the northeast monsoon over Tamil Nadu and comes as the Regional Meteorological Centre has forecast intense rainfall across several districts, including Chennai.
The reservoirs at Poondi, Chembarambakkam and Red Hills, which supply a major share of Chennai’s drinking water, received marginal inflow after a prolonged dry spell. The city’s five reservoirs, including Cholavaram and Thervoy-Kandigai, together held 3.8 thousand million cubic feet of water, or nearly 33% of their total storage capacity, according to the report.
Officials of the Water Resources Department said the waterbodies had also received marginal inflow in August, but the recent increase remains insufficient to produce a substantial rise in storage. They said more intense spells of rain would be necessary before the reservoirs could register a significant improvement.
The condition of upstream waterbodies is one factor limiting the pace of recharge. Tanks located upstream of the Red Hills reservoir are holding only 30% to 50% of their capacity. These tanks need several intense rainfall days to fill and begin releasing surplus water into the reservoir system, officials said.
The Regional Meteorological Centre said the northeast monsoon was vigorous over Tamil Nadu and forecast fairly widespread rainfall, covering up to 75% of weather stations, until October 22. In the 24 hours ending at 8.30 a.m. on Friday, Adayamadai in Kanniyakumari district recorded very heavy rainfall of 18 cm, while several other southern and interior areas received moderate to heavy showers.
The weather office issued an orange alert for six districts, with isolated areas of north Tamil Nadu expected to receive intense rainfall of up to 20.4 cm on Saturday. Chennai, Cuddalore, Namakkal, Karur and Thanjavur were among the coastal and interior districts forecast to receive heavy rainfall of up to 11.5 cm.
The Regional Meteorological Centre said the State could continue to experience an intense rainspell until October 22. An orange alert was also issued for parts of the Western Ghats, where very heavy rainfall was expected in isolated places until October 20. Chennai and Tiruvallur were forecast to experience very heavy rainfall on October 21.
For Chennai, the immediate water-management position therefore depends not only on rainfall over the city but also on the performance of the wider reservoir catchments and upstream tanks. The current storage level provides an early indication of monsoon recharge, but officials said the reservoirs would need sustained rainfall and inflows before storage improves substantially. Wet weather over the next few days is also expected to keep maximum temperatures close to normal across Tamil Nadu and Puducherry.
