How September rainfall compensated for August deficit filling reservoirs to brim

The turnaround in September compensated for the rainfall deficit in August.

Abundant rainfall in major parts of India has filled central reservoirs till brim. As on September 30, 130 major reservoirs in the country together now are filled with more water than what usually happens in other years in the corresponding period or is considered normal at this time of the year.

Water is required for the needs of drinking water, irrigation and hydro-electricity all through the winter months when the rainfall is scarce. This year too, the country did not see adequate monsoons but it had a marginal impact on the reservoir levels. August saw close to 25 per cent deficiency in and the reservoirs cumulatively held over 90 per cent of the normal storage in the first week of September. Most of the catchment areas of the reservoirs, though, got sufficient rainfall and held the reservoirs from drying up.

At present, according to the Central Water Commission report, 130 major reservoirs are filled with 138 billion cubic metres of water, which is about 80% of their combined capacity. In other years these reservoirs hold not more than 132 billion cubic metres of rainfall.

The CWC in its report said that the live storage available in 130 reservoirs is 104 per cent storage on average in ten years and 92 per cent of the live storage of corresponding period last year and.

The water level at reservoirs varied as the southern and western states saw higher than normal levels of water. The central region of Madhya Pradesh, Uttarakhand, Uttar Pradesh, Chhattisgarh are showing normal levels in their reservoirs. However, in Punjab the Thein dam, the only reservoir in the list of 130, is now storing 40 per cent less than normal waterfall.

Other big river basins like Tapti, Krishna, Godavari, Cauvery are better filled than Indus and Sabarmati basins. The rainfall pattern is not very different from that witnessed during monsoon months this year. The Northeast region received only 88 per cent rainfall, the northwest had 96 per cent rainfall. The Southern Peninsula has 111 per cent rainfall while Central India received 104 percent precipitation.

Month by month

India saw one of the driest Augusts in the last 100 years and it started to look like India is headed for a drought year. But the turnaround in September compensated for the rainfall deficit in August. September saw 35 per cent excess rainfall, after a particularly dry August, which is quite a rare phenomenon. Though September has been receiving excess rainfall for the last three years now.

This occurred due to Madden-Julian Oscillation, a moving equatorial wind-system that weakened the negative Indian Ocean Dipole, a wind movement phenomenon like El Nino effect in the Pacific Ocean. Cyclone Gulab that made landfall in Eastern India also contributed to unexpectedly high rainfall in September.

Mrutyunjay Mohapatra, Director General of the India Meteorological Department said that all atmospheric favourable conditions that bring rain in August prevailed in September as low pressure systems developed in the Bay of Bengal and kept the monsoon active over most of the areas in the country. Other monsoon months like June got 110 percent excess rainfall then normal while July got 93 per cent precipitation.