Advanced 2-D Modeling for Flood Reduction Studies and Storm Drain Master Planning

The IssueThe typical current approach to flood reduction analysis and storm water master planning/CIP development is to utilize unlinked one dimensional model software packages to model site hydrology and hydraulics. These models often have poor graphic outputs and require convoluted model interactions in order to estimate how various system components react with one another.A New Improved ApproachThis paper presents two unique and innovative case studies in which advanced 2-D modeling techniques have been applied for both flood reduction analysis and storm drain master planning. Both case studies utilized MIKE software and represent the first successful dynamic linkages in North America of three separate modeling packages bringing a new unique perspective to these types of studies. The studies represent a departure from traditional modeling approaches for these types of studies, and the presentation will focus on the added value provided by the new technology and a dynamically linked approach to these types of studies. Both studies incorporated MIKE 11 for one dimensional open channel flow, MIKE 21 for two dimensional overland flow, and MIKE URBAN for rainfall runoff modeling and storm drain network flow.The Salvador Creek Flood Reduction Analysis is an ongoing study for the Napa County Flood Control and Water Conservation District (District). A Storm Drain Master Plan was developed for the City of Sonoma, completed in 2011. For the Salvador Creek project, the dynamically coupled model is utilized to investigate various flood reduction alternatives including detention, flood walls, storm drain outfall flap gates, channel terracing and banking, and bypass channels. Model results will be presented along with discussion of next steps that are being evaluated with the City and County. For the City of Sonoma Storm Drain Master Plan, model development, results and master plan recommendations will be presented.Added Value/BenefitsThe presentation will introduce this new, innovative modeling technology to municipalities and agencies present at the conference, and focus on its application to common flood reduction or master planning studies. In addition to presenting the case study results, the presentation will be beneficial to the industry by focusing on the added value provided by this innovative approach. The presentation will focus on the following take-away message regarding the added value of the approach:1) Increased accuracy of floodplain and overland street flooding due to 2-D modeling results2) Better representation of depth of flooding and its duration3) Visual representation of flooding is a huge improvement over status-quo (reams of tabular output)4) Improved visual representation allows for better understanding of costs and benefits when comparing alternative projects5) Improved visual representation of projects and their benefits allow for more effective communication with stakeholders, the public, and city councils/agency boards6) Ability to refine alternative improvements allows development of more cost-effective CIP project developmentThe presentation will present this new 2-D modeling technology, its application to two unique case studies, and focus on the added benefit and value this approach provides to agencies and municipalities conducting flood reduction and storm drain master planning studies.