Presentation Title:
Applying Climate Change Indicator and Relative Sea Level Rise in Coastal Bridge Hydrodynamic and Scour Analysis

Formatted Title:

Applying Climate Change Indicator and Relative Sea Level Rise in Coastal Bridge Hydrodynamic and Scour Analysis

Background/Objectives:

Coastal infrastructures are highly exposed to extreme events and that exposure will increase due to sea level rise and climate change. For bridges over tidally influenced or tidally dominated waters, it is critical to factor in changing conditions in the context of hydrologic cycle and coastal hydrodynamics over the expected service life of the infrastructure assets. The Federal Highway Administration (FHWA) published design guidelines to estimate riverine peak flow discharge under climate change conditions using the Climate Change Indicator (CCI). FHWA also provides guidelines for estimating future relative sea level rise (RSLR) and updated storm surge heights along the coast. When adopted in bridge hydrodynamic and scour analysis, these guidelines help make the design of coastal bridges resilient. This presentation discusses the application of CCI and RSLR through bridge design case studies.

Approach/Activities:

CCI measures the change in the mean value of the annual exceedance probable, 24-hour duration, precipitation from observed to projected conditions, relative to the uncertainty in historical observations. Future climate change data at a given project site can be retrieved from the Downscaled Climate and Hydrology Projections (DCHP) database. The FHWA Coupled Model Intercomparison Project (CMIP) Climate Processing Tool is used to adjust model baseline to future. CCI is used to determine the level of analysis for future stream peak flows, which could involve statistical trend analysis, confidence limits, and hydrologic projections based on future precipitation and land use.

RSLR is the combined effect of ocean water elevation and vertical land movement (VLM) change at a location. Global mean sea level rise (GMSLR) or “eustatic” sea level rise is the average SLR across al the ocean basins, which is averaged 1.7 mm/year according to tidal gage records in the past century. The future GMSLR is estimated on the time-of-horizon of interest and the representative concentration path (RCP) from climate models. RSLR is used determine the tidal datum under future conditions.

Storm surge is the rise of the water level above the astronomical tide because of weather. Storm surge increases design still water elevation (SWL) and allows waves to attack higher elevations. The Coastal Hazards Systems (V2.0) developed by the Engineering Research & Development Center (ERDC) is a national coastal storm hazard data resource for probabilistic coastal hazard results and statistics, including surge heights, waves, currents, and wind, based on regional coastal numerical models.

Results/Lessons Learned:

Through a real-world coastal bridge design project, we applied the CCI to watershed hydrologic analysis and calculated RSLR for future storm surge at the mouth of the tidal river. These parameters were incorporated into a two-dimensional hydrodynamic model (SRH2D) to analyze currents through the proposed bridge opening. We then calculated bridge substructure scour depths which were used in bridge substructure foundation design.

Refine Results

Search Results

Group 1, Poster Board #40: Climate Change Resiliency and Adaptation (Poster)