Author(s): Seyed Hamidreza Sadeghi; Ramin Jalali Rad
Linked Author(s):
Keywords: Flood zoning; Hydraulic structures; HEC-RAS; GIS; Tehran; Iran
Abstract: Study on hydraulic behavior of rivers is one of the important works which can be made in river engineering field and it is much of interest for planners and decision makers. The application of simulation models is being considerably facilitated owing to the progresses made in computer technology and numerical techniques as well. The study on effects of hydraulic structures on river behavior is also very necessary to understand the interactions and looking for the pertinent approaches. The flow regime and condition in the river may vary where it is crossed by hydraulic structures such as bridges and dams. In the present research, an attempt has been made to study the effects of bridges on flow depth and area. The study was conducted in Darabad River as a part of Tehran urban watershed over which two bridges had been constructed. The flow was simulated using HEC-RAS computer model and by the help of data collected through surveying of 25 cross sections. The inundation areas corresponding floods having 25,50,100,200 and 500 years of return period were then zoned and the mean depth of the covered areas were ultimately determined with and without considering bridges. The results of the study revealed that the bridges have no serious effects on floods having return period less than 25 years. The effectiveness of bridges on depth and extension of flooded zones had been exaggerated by increasing the return period of floods initiated by 50 years of return period. Some other different fictitious conditions such as omission of first or second bridge was also studied and the results were compared with each other and the appropriate managerial techniques to reduce hazard risk were then suggested.
Year: 2004