Often, proposed construction activities need to be evaluated to determine what impacts the project will have on the surrounding floodplain. This is particularly true if the site is located in a FEMA designated floodway or if base flood elevations exist for the floodplain. Bridge & Stream has the expertise to evaluate the hydraulic impacts of a project using a one-dimensional or a two-dimensional hydraulic model. For large floodplains, the analysis often involves a bridge over the main channel with numerous relief bridges in the floodplain that also convey floodwater. GIS software packages are often used to manage and assemble the data for the hydrologic and hydraulic models.
The hydraulic impacts of a project may require modifications to the existing regulatory hydraulic model and the associated Flood Insurance Rate Maps. In such cases, Bridge & Stream would coordinate with federal, state, and local floodplain authorities to submit an application for a Conditional Letter of Map Revision (CLOMR).