What is Compound Flooding?
When it comes to flooding in Oceania, the conversation is often dominated by the danger of sea level rise, as this has become one of the defining characteristics of climate change in the region. However, flooding can occur through other mechanisms, which when excluded from resiliency planning, can exacerbate the threat in urban areas. The three principal mechanisms of flooding are coastal, fluvial and pluvial which are defined as the following:
Coastal Flooding: Inundation of land areas from the combination of sea level rise, storm surge, and tides
Fluvial Flooding: More commonly known as river flooding, this occurs when water extends over the typical boundaries of rivers, lakes, streams, and dams caused by increased rainfall upstream
Pluvial Flooding: Extreme rainfall can cause water to pool in any location (ex. Flash Floods) and is independent of being located near an existing body of water
Together, these three methods of flooding interact and compound on each other thus increasing the severity of a flooding event when occurring simultaneously. Lately, this effect has been getting more attention and is being analyzed specifically in the context of extreme weather events in the United States. However, the complexity at which these flooding mechanisms converge in coastal areas is difficult to model and forecast, therefore it is left out of the majority of preventative planning. This makes it incredibly dangerous in urban settings, as storm water infrastructure is not built to withstand the proper capacity, causing failures in areas that were thought to be resilient and protected. With 68% of the population residing in coastal urban areas in Oceania, it can be particularly dangerous for citizens. Read more ›