Young Hyun Park

Beach Erosion along the Northeast Texas Coast

Abstract Some areas of the Texas coast along the Gulf of Mexico are stabilized by beach nourishment or artificial protections, but the northeast Texas coast has been damaged and changed by short- and long-period erosion. The berm or dune that can act as protection from wave activities rarely exists, and mild, sloping beaches increase the potential of erosion in the study area. The upper Texas coast was monitored by Texas A&M University between 1999 and 2005. The measured beach profiles showed the morphological short- and long-period changes by overwash, and critical erosion was observed, especially by the landfall of hurricane Rita in 2005. The suspected causes of severe erosion were analyzed by comparing dune heights and beach widths, and it was found that overwash was one of the major factors causing erosion of the shoreline in the area. When storms made landfall in neighboring regions, such as southern Texas, Louisiana, Mississippi, and Alabama, overwash by long-period waves of remote storms was observed during the beach surveys. Overwash by remote storms could not be ignored, and it was an important contributor to continued beach erosion in the study area. Erosion caused by direct landfall of storms had significant effects on long-period erosion as well.

Development of a New Concrete Armor Unit for High Waves

ABSTRACT Park, Y.H.; Oh, Y.-M.; Ahn, S.M.; Han, T.H.; Kim, Y.-T.; Suh, K.-D., and Won, D., 2019. Development of a new concrete armor unit for high waves. Journal of Coastal Research, 35(3), 719–728. Coconut Creek (Florida), ISSN 0749-0208. Hundreds of new concrete armor units (CAUs) have been developed since 1950, but only a few have been used because of their low price and familiarity. Because the design wave height has been increasing as a result of climate change, the Korean government decided to develop a new CAU for protection against high waves. Therefore, a new research project to develop a new CAU that considers stability, structural strength, economic feasibility, casting efficiency, and constructability was started. The new CAU was called Chi Block. The hydraulic stability achieved a Hudson stability coefficient of more than 13 at a significant wave height of 10 m by adopting a conservative approach. Chi Block can be installed in both uniform and random placements and can be used as an overlay for repair. A new placement for Chi Block was invented, and it features the advantage of functioning like a 1.5 layer. Although a single layer generally has a higher overtopping rate than a double layer, Chi Block, on uniform placement, has a performance near that of the Tetrapod.

Development of a new armor unit against high waves

Coastal hazards such as high waves are expected to increase due to global climate change. Therefore, we investigated new armor unit structures for disaster prevention. Recently, a concrete caisson has been used in many breakwaters against high waves in South Korea, but the demand for concrete armor unit has increased due to the high cost and many installation requirements. Though many new armor units have been developed over the world since Tetrapod in 1950, few have been used due to lack of systematical development. The representative armor units in current use have many advantages, but they cannot be applied to waves higher than 8 m. One of the new armor units developed by the design guide based on recent trend and hydraulic model experiments were conducted. The new armor unit was developed as a single layer due to cost effectiveness. However, the thickness is close to 1.5 times by overlapping the alphabet A and V. It showed higher overtopping compared to a double layer because of the thickness and the high packing density. It has a high interlocking vertically but low horizontally. It shows good stability at 9 m in model testing.