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Following a major rainfall or flood event, questions typically arise regarding the magnitude and frequency of the event. How does that storm compare to design rainfall depths? Did we just experience a 100-year flood? What’s the difference between a 100-year storm and a 100-year flood?


Bridge & Stream has experience comparing observed rainfall amounts to nearby rain gauge data and to rainfall frequency maps to estimate the frequency of the storm. Our staff also has experience in calculating Probable Maximum Precipitation (PMP) depths for developing Probable Maximum Flood (PMF) hydrographs.


We can perform a site visit to survey recent high water marks and obtain cross sections of the floodplain in order to develop a calibrated hydraulic model and determine the magnitude of the flood event. Our staff has experience in routing PMF hydrographs to assess spillway adequacy, performing dam breach analyses, and flood inundation mapping.

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