Flood frequency prediction using Gumbel's and Log-Pearson method for Siang river

Siang is the major river flowing within the Pasighat town of Arunachal Pradesh and poses flood inundation danger to the town. Flood frequency analysis is carried out for Siang river on the basis of peak flow data (46 years) collected from Komlighat gauging station. The hydrologic flood flow data is found to be fitted well to the Gumbel and Log-Pearson Type-III distribution function. Flood magnitudes of the Siang river have also been predicted and information generated for policy makers to adopt flood protection measures. The hydrologic parameters like design discharge of 30, 520 cum at 100 years recurrence interval, HFL=156.3 m above msl, a free board of 2 m are recommended for design of required flood protection measures. Levee, stone spur, turfing, revetment and apron works and countryside plantation are among these measures. These measures are required for preventing the Pasighat town and its adjoining areas including the three existing hydroelectric plants, viz, Ymbung, Sille and Rina from future flood havoc.viz.