Transatlantic project works to fortify coastal resilience against rising seas

Climate change is leading to an increase in sea level rise, putting millions of people in danger of severe coastal flooding in coming years.

Sherif Abdelaziz, associate professor in the Charles E. Via, Jr. Department of Civil and Environmental Engineering at Virginia Tech, is collaborating with researchers from Heriot-Watt University in Edinburgh, Scotland, to find solutions to keep coastal areas safe by enhancing the resilience of sea walls against increasing coastal flooding. The PIONEER project aims to be the initial step in a global collaboration to strengthen coastal defenses.

With climate change-driven increases in sea levels, coastal flooding events are predicted to rise in frequency and severity. In the United States, coastal sea levels are expected to rise by 0.25 to 0.30 meters by 2050. This is the same amount that was measured between 1920 and 2020.

Approximately 148 million people worldwide are currently exposed to coastal flooding events, which underscores the urgency to bolster coastal defenses. According to Abdelaziz, about 40% of the population in the United States lives in counties on the coast. Coastal cities are being forced to invest significant funds to protect their residents. For example, Staten Island, New York, is investing $165 million to build a seawall for resilience against sea level rise. This will help protect New York City from financial and social damages similar to those experienced after Hurricane Sandy in 2012.

The collaboration was triggered by the ongoing research of Abdelaziz's group, utilizing Virginia Tech's retaining wall research facility at the Prices Fork Geotechnical Research Laboratory to assess the impact of temperature on earth retaining structures, which are engineered structures that are built to prevent erosion of the shoreline. This project will complement the current research by adding another level of complexity by measuring how much water fills in the soil.

Melis Sutman, assistant professor in geotechnical engineering at Heriot-Watt's School of Energy, Geoscience, Infrastructure and Society earned her master's degree and Ph.D from Virginia Tech in geotechnical engineering in 2015. Because she is familiar with the ongoing research at Virginia Tech, the collaboration between the two universities was a seamless next step in the research.

"This is an interesting study because it combines—probably for the first time—the interactions for the effect of the water flooding on soils, and subsequently, on shoreline protective structures," Abdelaziz said. "We will be able to assess how all these factors interact together so we can better design our shoreline protective structures to sustain the increasing intensity of waves and floods."

The United States and the United Kingdom both face significant challenges, such as the loss of land near the shoreline, threatened coastal communities, and inadequate stability of near-shore infrastructures, including ports and roadways, due to potential sea level rises. This research will focus on understanding how the soil behind seawalls is affected by repeated wetting and drying cycles caused by waves overtopping the walls. By pinpointing vulnerable areas, researchers aim to enhance the design and resilience of sea walls.

The PIONEER project involves laboratory testing using innovative devices, such as a thermo-hydro-mechanical direct shear interface device at Heriot-Watt, to simulate various climate change and emission scenarios efficiently. Then Virginia Tech will complement those lab-scale tests with experiments on a full-sized, 4-meter-high retaining wall to investigate the effects of temperature, water pressure, and other parameters.

"Each of our universities has equipment that is highly valuable to this research. This allows us to collaborate to develop innovative solutions to problems that are affecting countries worldwide. Research like this has no geographic boundaries," said Abdelaziz of the international collaboration.

As sea walls continue to play a pivotal role in safeguarding communities, this research initiative marks a crucial step forward in building resilience for a sustainable future.

"Investing our efforts into sea wall research is not just safeguarding coastal communities, but it is building resilience that ensures the stability and prosperity of those communities for years to come," noted Abdelaziz.

Provided by Virginia Tech