Impact of Coastal Forests on Geomorphological Changes of Coastal Dunes: A Case of the Sohawang-ri Foredune, Chungnam Province

해안사구 지형변화에 대한 해안림의 영향: 소황리 전사구를 사례로

This study shows that coastal sand dunes are negatively affected by coastal forests. In South Korea, planting pine trees on the dunes has been carried out to stabilize the dune landscapes and protect residential areas from coastal disasters since the 20th century. However, this strategy could reduce the resilience of dunes. In this study, we selected three monitoring sites with automated weather stations to compare the geomorphological and environmental characteristics between tree-covered and grass-covered dunes at Sohwang-ri, Boryeong-si, Chungnam Province for three years. In addition, we monitored the rates of erosion and deposition using eight pins along the dune crests. We found that the forest affected both wind velocity and direction, resulting in decreased blown sand supply to the dunes in front of the forest. The velocity of the strong winds faster than 5 m/s diminished to 10%-30% of the control sites, and the direction of northwesterly wind were skewed to the north by about 6°. Sand deposition occurred at about 15-20 m away from the pine forest and the amount was only 1/10 of the deposition within the grass-covered dunes. This study suggests that planting trees in coastal dunes is an undesirable strategy with negative impacts on the landscape management.