Analysis of combined flood frequency in calculating the depth of abutment scour around the piers to determine the discharge with safe return period

摘要

The main purpose of this study is determining of discharge with safe return period to preventing of abutment scour around the pier. Today scour is one of the important issues in river and coastal engineering and lots of bridges destructions occur dueto this phenomenon. This subject can be useful for river investigations and design of pier. In this research after obtaining statistics and data from water and power organization of Khouzestan province, for determining of essential hydraulic parameters HEC-RAS software has been used and study area simulated with this software. Then the appropriate formula for determining scour depth was chosen and considering the depth of for different return periods, the appropriate discharge as the design discharge was chosen. For this study that conducted for Karun River located in Ahwaz city around the seventh bridge can be concluded that by discharge with return period of 50 years more than 85% depth of scour has occurred and for increasing of safety a discharge with 100 years return period can be selected as design discharge.