My Fulbright research is based on the following proposal summary and I plan to explore additional topics.
Merging ecology with safety: the effects of floodplain restoration on loss-of-life
Floods are the number one natural hazard in the world in terms of loss of life and damages, and low-lying delta areas are some of the most vulnerable because they face flood threats from both rivers and the sea. In the face of increased flooding due to sea-level rise, land subsidence, and climate change, both the Rijn-Maas-Scheldt Delta in the Netherlands and the Sacramento Bay-Delta in California are at great risk. Dikes in both deltas protect important agricultural land, human communities, and critical ecosystems. The strategies implemented to defend such areas against flood disaster, therefore, are critical to the sustainability of these regions. In the Netherlands, decision-makers consider threats to human life in the new flood risk management policies, but in the United States, this component is not directly taken into account.
My project will examine the Dutch method for estimating the loss of life during floods to provide new critical information for California’s Bay Delta where no such comprehensive analysis has been completed. The overall research goal is to investigate the direct effects of non-structural flood defense measures (such as giving room back to the rivers) on the risk to human life, and to build more support for these types of measures as risk management strategies in California and the Netherlands.
After 1,835 people died when the North Sea overtopped dikes in Zeeland on February 1, 1953, the basis for the Netherlands’ flood defense became “Never Again.” As a matter of national interest, the Dutch built the massive Delta Works projects on the North Sea Coast and subsequently established the highest safety standards in the world to protect the low-lying country from flooding. Dutch flood management and policy is constantly evolving. As such, the impacts of floods on mortality have recently entered the dialogue on flood defense so that the costs and benefits of certain strategies can be better assessed and decision makers can then choose an appropriate level of protection for a given area.
Currently, the most widespread strategy for managing flood risk in the Netherlands and the rest of the world is the use of technical measures—building high dikes and dams to keep out the sea and the rivers. Improved safety by this approach, however, has come at the expense of coastal, estuarine, and floodplain ecosystems. Estuaries and rivers around the world, including the Rijn-Maas-Scheldt Delta and the California Bay-Delta are in decline, and tidal marshes and floodplains once rich in habitat have been reduced to a series of sediment-starved canals and concrete channels, devout of native life, with declining fisheries and human communities whose economies depend on them.
While non-technical flood defense measures such as ecological restoration along floodplains and the coast may enhance both ecology and safety, they tend to be less common because they are expensive, and because their benefits are not well understood. However, one new Dutch method could provide the link between the two. The loss-of-life model developed by Bas Jonkman at the Delft Technical University (TU-Delft) estimates that about 1% of an exposed population is likely to die during a flood. Further, empirical evidence suggests that mortality increases with water depth. In theory then, flood defense measures that reduce the depth of inundation by even a few centimeters, such as these non-structural more ecologically beneficial measures, could also result in a direct reduction in human mortality.
Over five phases, my project will use the Dutch loss-of-life model to show the direct public safety benefits of ecologically restoring floodplains and expanding floodways in the California Bay Delta. I intend to: 1) learn the Dutch method (Jonkman 2007) for estimating loss of life, 2) apply the method to estimate loss of life in the California Bay Delta Region under two flood scenarios, 3) identify floodplain restoration and expansion opportunities in the Bay Delta and model their hydrologic effects, 4) apply the method to the same area to estimate loss of life in region after the floodway expansion, and 5) compare the results to quantify the changes in mortality.
My project provides an excellent forum for knowledge exchange and strategic collaboration between the Netherlands and the United States. Dutch and American agencies have begun restoring floodplains and expanding floodways, but little work has been done to link these projects to human mortality. As such, projects with ecological benefit tend to receive less attention and funding than their larger, more technical counterparts like dikes. The Dutch “Room for the River” projects are few and far between, and though California developed plans for a floodway expansion and bypass system in the late 1890s, only a small portion of it was built.
In light of a new government in the Netherlands, and California’s current redesign of its flood defense system over the next two years via the Central Valley Flood Management Plan, this project provides a unique opportunity at a critical time for rethinking policies and creating new strategies in both places. These results therefore are directly applicable to both regions where projects merging ecology and safety have great potential to proliferate.