Compound flooding in the San Francisco Bay area

Flooding can result from a combination of multiple drivers, such as rainfall, river discharge, astronomical tide, storm surge and waves. Such ‘compound flooding’ is also an issue in the various creeks draining into the San Francisco Bay. High water levels in these creeks may occur due to high tidal levels in the Bay, high discharges, or a combination of both. The appropriate way to quantify return periods of water levels in a case with multiple flood drivers is through probabilistic hazard analysis, which explicitly accounts for joint occurrence probabilities of flood drivers as well as their combined impact on flood levels. However, such analysis can be cumbersome, and practitioners may lack the required experience. Therefore, depending on the available resources, a more pragmatic alternative approach may be preferred. In this report, such method is developed for the creeks draining into the San Francisco Bay.