Assessing Multiscale Hydrometeorological and Hydrologic Feedbacks due to urbanization over the San Francisco Bay Area

Urbanization is occurring around the world at a rapid rate, with urban populations expected to increase from 3.6 billion in 2011 to 6.3 billion in 2050 (Heilig, 2012). Among the many challenges associated with urbanization are the consequences manifested in regional hydrometeorology and flood risk. Many studies have examined the effect of urbanization on hydrometeorology and flood risk individually, yet effective planning requires understanding the combined effect of hydrometeorologic and hydrologic modification. In this study of the larger San Francisco Bay Area, we select large regional storms with significant flooding and separate the effects of various surface properties (e.g., complex topography, urbanization) on storm dynamics. We further select small watersheds which experience flooding and analyze them to separate the effects of hydrologic properties (e.g., geomorphology, land use) on flooding behavior. These two analyses integrate to demonstrate the full effects of land use on flood risk by connecting regional land use patterns with hydrometeorology and how this interacts watershed-scale land use to generate floods. This work demonstrates the need to consider hydrometeorologic and hydrologic effects of changing land use for a complete picture of flood behavior. Results will be applicable to the greater Bay Area which is has numerous areas designated for urbanization within the spatial extent of this study.