Additionally, the modeler is referred to chapter 12 of the User's Manual, chapter 10 of the Hydraulic Reference Manual, and to HEC No. The modeler is referred to chapter 6 of the User's Manual and to chapter 5 of the Hydraulic Reference Manual for additional discussion on modeling bridges. This example will focus upon the analysis of the bridge scour. The procedures for performing long-term effects are discussed in the HEC No. The user must determine the long-term effects before applying the bridge scour computations in HEC-RAS. The program does not have the capability to perform long-term aggradation or degradation. The scour equations for these components are based upon the methods outlined in Hydraulic Engineering Circular No. The scour computations in HEC-RAS are comprised of three components: contraction scour, pier scour, and abutment scour. Once this model is developed, the bridge scour computations can then be performed. This model should be calibrated to the fullest extent possible in order to accurately determine the hydraulics of the river reach. To perform the analysis, the user must first develop a hydraulic model of the river reach that contains the bridge.
This example will demonstrate the use of HEC-RAS to perform a bridge scour analysis.
