FLOOD FREQUENCIES IN SOAN VALLEY

Estimation of peak floods in a watershed where industrial and housing development is present always has prime importance to determine extent of flooding and its damage. Such type of estimation guides that these developments are safer during flooding or not. Soan valley is one of the important valley in which major cities like Rawalpindi, Attock and a part of Islamabad is located. This study is based on long term recorded flood data along the Soan river at various locations. Detailed flood frequency analysis was carried to select the best fit frequency models at various locations in Soan river. The data were processed to check its consistency and outliers. The estimated peak of the floods in Soan at Chirah, Rawalpindi and Dhok Pathan for 100 year return period worked out to be 3787, 5752 and 9842 m 3 /sec respectively. These results may be helpful for future development along the river by determining the elevation of flood encroachments along the banks. Key word: Peak floods, flood frequency, outliers, catchment, gauging stations, return period.