Bozeman Creek Hydraulic Model

Running through the heart of the City of Bozeman, Bozeman Creek has been narrowed and straightened, its banks armored with rock and concrete, its riparian vegetation removed or reduced to a thin green line. A coordinated effort led by community organizations, city, state, and federal partners, consulting professionals and landowners began in 2010 with a vision to create a naturally functioning and connected creek corridor with healthy riparian areas and floodplains. To serve as a planning, design, and permitting tool for on-going and future channel and habitat enhancement projects, AESI created a HEC-RAS hydraulic model of Bozeman Creek through downtown Bozeman.

The hydraulic model was geo-referenced using HEC-GeoRAS and included several bridges and other hydraulic structures. Additionally, AESI determined natural bankfull channel geometry for the highly altered stream system to serve as a benchmark for future channel design. Finally, a proposed conditions model was created to estimate the effects from naturalizing the channel geometry, creating an inset floodplain, and replacing a small bridge with a larger structure for a small reach near City Hall. Key project features include:

• Ground survey: 64 cross sections and 11 bridges;
• Processing 2007 LiDAR data to establish a digital terrain model of the floodplain;
• Development of an existing conditions model in HEC-RAS of roughly 4800 feet of Bozeman Creek;
• Development of a HEC-RAS model representing proposed channel modifications; and
• A comparison between the existing conditions model and the FEMA effective model.