Simply Put: South dams aflush, north drierhttps://indianexpress.com/article/explained/water-reservoirs-india-monsoon-south-india-cheruthoni-idduki-dam-shutter-open-kerala-flood-5299792/

Simply Put: South dams aflush, north drier

Countrywide storage close to average for halfway stage of SW monsoon, east reservoirs too doing well. Out of the 91 reservoirs, 65 currently have more than 80% of normal storage and 26 have below 80%.

Idukki dam shutter opened after 26 years in Kerala after heavy rain
Cheruthoni dam, commissioned in 1975, has been opened only two times, both during the northeast monsoon in the months of October-November. (Express Photo)

The opening of five shutters of the Idukki reservoirs system Thursday underlined a generous monsoon that has descended on South India this year. Of the 22 reservoirs that have more than 90% of total live storage capacity, 17 are in Karnataka, Kerala and Tamil Nadu, with the rest in Maharashtra (4) and Tripura (1). Among those with the lowest storage is the Sardar Sarovar Dam in Gujarat, which has 1% of total live capacity, according to the latest update Thursday.

READ | Idukki dam shutter opened after 26 years in Kerala following heavy rain

Figures released by the Central Water Commission (CWC) show that the country’s 91 major reservoirs have a total of 77.554 billion cubic metres (BCM) stored in them. This is 48% of their total storage capacity, 5% over the storage at the same period last year, and 98% of the average storage of the last 10 years at the corresponding period.

Of the five regions, the northern, western and central regions are not as well placed as the eastern and southern regions. The central region with 12 reservoirs includes states such as Uttar Pradesh, Uttarakhand, Madhya Pradesh and Chattisgarh. The Indian Express has reported earlier that monsoon patterns across this region, specifically in UP and Bihar, saw “deficit” or “large deficit” levels of rainfall in the first 50 days of this monsoon period. Of the districts that the Met department has recorded rainfall data for, many are in UP and Bihar.

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Out of the 91 reservoirs, 65 currently have more than 80% of normal storage and 26 have below 80%. The CWC figures show that the basins of the Krishna, the west flowing rivers of South Godavari, the Mahanadi and Cauvery appear to be doing well, while the Indus, Tapi, Sabarmati and Narmada are deficient.

The water being released from the Idukki reservoir will travel through the Cheruthoni river to meet the Periyar after a distance of one kilometre. (Express Photo)

Himanshu Thakkar from the South Asia Network on Dams, River and People observed: “In the Cauvery basin, rainfall is 3% below average and yet all the reservoirs are full. This could be signs of catchment degradation. Historically, this has not happened, dams are not full during the southwest monsoon. The catchment is the capacity to hold rainfall which requires forests, local water bodies and wetlands.” Thakkar says that this could be an indication that all is not well with the area surrounding the dams. “The rest of the monsoon also does not look promising.”