Bayou Auguste is a coastal stream that drains into Back Bay of Biloxi. The bayou flows through 390 acres of urbanized downtown and residential areas. Due to increased development, the bayou experienced increased stormwater flow, nutrient loads, and sedimentation in 2016-2018. Cypress performed a floodplain restoration project in response to these impacts, repairing damage to wetlands, including previously restored tidal marshes.

Ecosystem Restoration History

Between 2010 and 2015, a series of projects were undertaken to restore natural hydrology, restore floodplain marshes from converted uplands, filter stormwater, and re-establish habitat through native plantings. Cypress worked with community stakeholders and funding partners in the design and implementation of the projects. This initiative won a first place USEPA Gulf Guardian Award in 2015, in part for the watershed and water quality benefits the projects provided to the local area.

Floodplain Impacts

After 2015, utility work in the watershed led to increased sedimentation within Bayou Auguste. As a result, the floodplain was altered, changing the ecosystem and hydrodynamic patterns within the bayou. In 2018, the Land Trust for the Mississippi Coastal Plain (LTMCP) hired Cypress to complete an ecosystem restoration plan. This restoration plan includes with construction plans, specifications and a hydraulic model of the tidal bayou. The purpose of this restoration plan is to repair the damage done to the bayou, restoring the floodplain and habitats to 2015 conditions.

Floodplain Restoration

Cypress personnel used HEC-RAS to create a one-dimensional flow model of Bayou Auguste and its watershed. The HEC-RAS model simulated ten different design storms and their effects on the floodplain. These simulations helped Cypress and government permitting agencies to understand how the proposed improvements within the bayou would impact flood regimes and the watershed. As a result, Cypress was able to demonstrate that the restoration project will not increase flooding within the watershed. Cypress successfully completed project design in 2019 and is supporting LTMCP on construction administration in 2020.

HEC-RAS floodplain modeling
CAD grading plan for floodplain restoration