The monsoon forecast is for lower intensity rainfall from Sunday, but the very heavy to heavy rain in parts of Gujarat, south Karnataka, Kerala and Tamil Nadu in recent days has brought healthy storage to many reservoirs in the southern States.
Idukki in Kerala, Karnataka’s K.R.Sagar and Srisailam in Andhra Pradesh received steady inflows on Saturday.
Four days of heavy rainfall in Wayanad — which sends water to the Kabini dam — and in the Karnataka ghats eased fears of a deficit in the Cauvery. On August 6, storage in four reservoirs along the river was just 37% of capacity, but by Saturday morning, storage had doubled to 75%. The inflow into K.R.S. dam exceeded one lakh cusecs, enough to fill it in less than three days.
4% increase overnight
Idukki, Kerala’s biggest reservoir, improved storage by 4% overnight, touching 34%, which is 503 million cubic metres (MCM) of water against the maximum of 1,460 MCM. Intense rain along the Western Ghats sent big flows into reservoirs on the Krishna.
Almatti and Basava Sagar dams on the Krishna had inflow and outflow exceeding five lakh cusecs, or, 45 thousand million cubic feet (tmc ft) of water daily. This surpassed the previous high of 4.5 lakh cusecs in 2005 when large parts of north Karnataka were flooded, said G.S. Srinivas Reddy, Director, Karnataka State Natural Disaster Monitoring Centre. “Any rain will lead to increased inflow. We expect it to touch six lakh cusecs in the coming days,” he said.
While the two dams have a combined capacity of 145.6 tmc ft, authorities have kept the current storage at 96.94 TMC. Due to the large inflows, some headroom was retained in both dams to avoid flooding. On August 1, authorities lowered storage in the dams by 31.12 tmc ft to absorb excess flows from Maharashtra. The Godavari and Krishna rivers continued to be in spate in Andhra Pradesh. Water Resources Department officials said the inflow and discharge at Sir Arthur Cotton barrage at Dowleswaram in East Godavari district was 15.30 lakh cusecs in the evening, up from 14,05,320 cusecs before noon.
The Srisailam reservoir on the Krishna was receiving 4,13,479 cusecs at 11 a.m. and the outflow from 10 out of 12 gates was 1,79,546 cusecs aided by flood discharge from Narayanpur dam in Karnataka. Over one lakh cusecs was received at Nagarjuna Sagar in Guntur district and 6,437 cusecs was being discharged.
The Vamsadhara in Srikakulam district and Thotapalli reservoir in neighbouring Vizianagaram were also receiving large inflows: 20,448 cusecs and 11,927 cusecs respectively.
Mettur benefits
In Tamil Nadu, Mettur, a major dam, was receiving good inflow from Karnataka. On Saturday evening, it stood at nearly 75,000 cusecs. This was expected to increase to one lakh cusecs by Sunday. The dam had a storage of 23 TMC against its capacity of 93 TMC.
With steady and heavy inflow, it could realise 8-9 TMC daily and reach its full capacity in 8-9 days, an official said. Besides irrigating Cauvery delta districts, the Mettur surplus is diverted to Veeranam tank, which augments water supply to Chennai.
In western Tamil Nadu, Amaravathy dam in Tirupur district got heavy inflow, recording a level of 70 feet against a full reservoir level of 90 ft.
Smaller dams in Kerala also received notable inflows. Malampuzha in Palakkad recorded an inflow of 6,095.31 cusecs, Kallada 3,678.38 cusecs and Kuttiyadi 16,181.18 cusecs, the Irrigation Department said.
The Pamba reservoir was 35% full on Saturday, with a storage of 15.7 MCM, while Sholayar recorded 64.8 MCM (full level 149.2), Idamalayar 414.1 MCM (1,017.8) and Matupetty, 13.75 MCM (55.2).
In the Narmada system in central India, of 11 dams on the river, gates of only Bargi dam, near Jabalpur, remained open. Of 21 gates, 15 were opened as the water level had touched 421.75 metres, just close to the danger mark of 422.76 metres at 6 p.m.
