PARENT SESSION
Poster Session #13: Salt Marshes.
Monday, August 5. Presentation from 5:00 PM to 6:30 PM. Exhibit Hall B & C, TCC

Quantitative modeling and conceptual design as tools in salt marsh restoration and mitigation planning.

MACKAY, KEVIN^*,1, STOCK, JENNIFER¹, HALL, BRAD², ODELL, ROB², BROOKS, PETER², ¹ Jones & Stokes, Sacramento, CA² Northwest Hydraulic Consultants, West Sacramento, CA

ABSTRACT- Beginning in the mid-1800s, large areas of San Francisco Bay′s tidal marshes and mudflats were filled, diked, or drained to create farmland, to construct evaporation ponds for salt production, and to provide land for industrial and residential development. The filling and diking of tidal baylands has greatly reduced the amount of available habitat for many wetland-dependent fish and wildlife species and has had significant effects on the physical and biological functions of associated habitats. A number of restoration and/or mitigation projects have been planned and implemented in the Bay over the last 20 years, but they have met with varying levels of success; less successful projects have typically been those that failed to reestablish the physical processes essential to marsh development. As part of the mitigation planning process for the San Francisco International Airport (SFO) runway reconfiguration project, Jones &Stokes and Northwest Hydraulic Consultants have developed an innovative design process based on identifying and restoring the physical processes necessary to create fully functioning marsh ecosystems. Mitigation planning for SFO has focused on providing subtidal habitat through restoration of function on adjacent tidal marshlands. Key aspects of the SFO design process included the following: analyzing historic and present-day geomorphology of Bay system tidal basins to identify appropriate scales of drainage patterns, channel planforms and sinuosities, and channel bifurcation ratios and to derive a quantitative relationship between slough channel size and drainage basin area; modeling pre- and postproject tidal hydraulic conditions within connecting slough channels and tidal marsh plains; and developing a methodology to quantify postrestoration area of aquatic habitats. In addition, hydraulic modeling was used to assess the ability of connecting slough channels to convey the full postrestoration tidal prism volume, which is essential to re-establishing the physical processes necessary for development of marsh vegetation. This combination of quantitative modeling and conceptual design supports restoration of full hydraulic and biological habitat functions while ensuring that specific numerical mitigation objectives will be met.

KEY WORDS: salt marsh restoration, San Francisco Bay, mitigation planning, hydraulic modeling