The City of Redlands, located in San Bernardino County, California, has been plagued by flooding in their historic downtown area for over 125 years. Four major watersheds and undersized aging infrastructure contribute to flood depths of over 1 to 1.75 meters through the downtown area. Several studies have been completed over the last few decades to identify flood hazards and potential solutions, with varying results. As part of their new Master Plan of Drainage, the City requested a comprehensive study to identify potential improvements and their potential impacts to the existing floodplain. The results of this evaluation are being used to establish flood risk maps in addition to establishing a basis for future Drainage Impact Fees.

To pay for the required drainage improvements, the City determined that they would have to increase their Drainage Impact Fees. To obtain this the City needed the approval of both the City Council and the general public.

The project involved modeling an area of about 800 x 6000 ft of the downtown streets of the City of Redlands which were prone to flooding due to an under capacity channel.

As Tom Ryan of RBF commented. "As with many non-professionals the stakeholders of the City of Redlands would not necessarily have appreciated the technical flood modeling data expressed in 2D format, whereas we were confident that if we could display the data more realistically, their appreciation of the flood hazards would improve enormously. This is why I approached FORUM8 regarding the potential to use their interactive 3D simulation software (VR-Design Studio)."

To support the consensus building through the public outreach and Council approval, VR-Design Studio was used to create a 3d-hybrid animation to graphically show the flood hazards of the 100-year storm event, and the risks associated with not improving the existing storm drain infrastructure. The video animation was based on the results of a complex coupled 1-Dimensional / 2-Dimensional (1D/2D) XPSWMM hydraulic model.

Communicating technical calculations to non-technical audiences has been an issue engineers continually face. When the audience consists of stakeholders or decision makers, the issue of communication becomes much more important. What we have learned from this process, based on several projects, is the more realistic the calculated results appear, the more the audience understands what the engineer is communicating. Assuming the calculations are performed correctly, this process produces trust in engineer's work.

In the United States, there has been a recent campaign from the State and Federal agencies to communicate to the public the existing flood hazards and the need for major flood prevention (storm and Sea Level Rise). Based on the responses we' ve had in presenting VR-Design Studio animations at recent conferences, this software could be a valuable asset in this process.

Mr. Tom Ryan		The office located in Irvine city, CA