Long-Period Fluctuations in Monsoon Floods in the Deccan Peninsula, India

In the present study, the temporal patterns of monsoon floods on five large rivers of the Deccan Peninsula have been investigated. Analyses of the long-term annual maximum discharge/stage data, available for the last 100 years or so, show non-random behaviour in terms of distinct periods of high and low floods. The normalized accumulated departure from mean (NADM) plotting method has been used to identify great periods of below-average (low) and above-average (high) floods. Examination of the data reveals lower frequency and magnitude of large floods during the late-1800 and early-1900 period, and a period of increased frequency of large floods between 1940s and 1960s. The results of the investigation also indicate that the high (low) flood response is consistent with increased (decreased) precipitation in the basins. There is a clear evidence of an enhancement in the magnitude and frequency of large floods in the post-1940 period.