One-Dimensional (1-D) vs Two-Dimensional (2-D) Hydraulic Modeling for Multiple Openings; A Case Study in Georgia for Comparison and Calibration

One-dimensional (1-D) and two-dimensional (2-D) hydraulic modeling was used to design the SR 129 multiple bridge crossings of the Canoochee River in southeast Georgia on the coastal plain. This approach produced a bridge cost savings of over $150,000 and illustrates how 2-D modeling can be used to improve the design efficiency and hydraulic characteristics of multiple bridge opening sites. The 2-D hydraulic modeling of the natural and existing conditions was performed using the U.S. Army Corps of Engineers RMA-2 model. HEC-RAS was used for the 1-D modeling of the same conditions, and its multiple opening routine was calibrated to generate similar flow distributions between the bridges for the design storms, and was then used to develop proposed design alternatives. 2-D modeling was then performed for the selected configuration to provide final verification that the design parameters were met.