9-A case study of unprecedented floods in the Godavari river during August 1986.

Abstract

Unprecedented historical floods were recorded in the lower reaches of the Godavari River during 13-20 August 1986. According to available records since 1881, the highest gauge level was recorded at Dowlaiswaram on 16th August 1986, while an all time hLgh gauge level was recorded at Bhadrachalam on the same day. In this paper an attempt has been made to bring out the synoptic situations and the rainfall contribution of each sub-basin to the floods. The average depths of cumulative rainfall of storm period is derived by Depth Area Duration analysis, treating sub-basin as a unit. A comparison has also been made between the storm period average depths with that of August normal rainfall depths. The historical floods in the lower reaches of the Godavari River during August 1986 were the direct result of heavy falls associated with the Deep Depression of Bay of Bengal Origin. This system moved initially over the eastern parts of the basin which subsequently skirted along the north-eastern. parts of the basin. Associated heavy rainfall zones were located over central and eastern parts of basin, which contributed to the floods in the lower reaches.