An analysis on coastal topography change in Haeundae Beach using 3D geospatial information

Abstract

본 연구는 부산에 위치한 해운대 해수욕장을 연구지역으로 선정하고, LiDAR자료와 GPS 측량자료, 수심측량자료를 이용하여 연안 관리에 필요한 기초자료로 활용할 수 있도록 분석해보고자 한다. 본 연구지역인 해운대 해수욕장은 지형적으로 남쪽으로 개방되어 있고, 외해와 바로 접해 있기 때문에 외해로부터 직접적인 파랑의 영향을 받는다. 이러한 지리적 특성에 따라 2005~2007년 사이에 발생한 태풍에 의해 해운대 해수욕장은 직간접적인 영향을 많이 받은 것으로 사료되며, 또한 양빈 사업에 의해 많은 모래가 퇴적된 것으로 예상되어 이를 연구를 통해 정량적으로 분석해보았다. 이러한 변화를 살펴보기 위해 2005년 8월의 GPS 측량 데이터와 2007년 10월 항공 측량한 LiDAR 데이터를 이용해 두 시기의 DEM 자료를 생성하였고, DEM을 비교 분석하여 해빈 단면 변화를 살펴보았다. 그리고 수심 측량 자료를 이용하여 해저지형도를 제작하고 이것을 바탕으로 해저 지형의 침퇴적 현황 및 해저지형으로 퇴적되는 토사량을 계산해보았다. 또한 측량 회차별로 비교 분석하여 계절별에 따른 영향을 계산하였고, 해저지형을 등간격으로 나누어 각 구간별로 침퇴적 경향을 분석해 보았다. 그 결과 해변 지형의 표고변화는 2005~2007년까지 약 0.15m 정도의 퇴적현상이 발생하였고, 구간 별 분석 결과 주로 해수욕장의 양쪽 끝에서 주로 발생한 것을 알 수 있었다. 또한 계절별로 침퇴적을 반복하고 있었고, 여름에는 침식, 겨울은 퇴적되는 경향을 보였다. 또한 해저지형으로 퇴적되는 토사량을 구간별로 볼 때, 해안 서쪽이 동쪽보다 많았다. 이 같은 연구 결과는 연안 통합 관리 시스템에 유용한 자료로 활용될 것으로 사료된다.

This study gained 3D spatial information of the coastal topography using LiDAR data taken in 2007, and based on the data, gave a quantitative analysis of the changes in the cross-section of the coastline with the GPS-surveyed data in 2005. This research obtained 3D spatial information of the coastal topography using the LiDAR data taken for the year 2007, and based on the information, analyzed changes in coastal cross section as well as GPS surveyed data for the year 2005. It also investigated changes in beach width by section by digitizing the coastline from the coastal monitoring images, and analyzed the evolvement of erosions and deposits on the seabed by season through GIS 3D analysis technique using the sounding data measured 5 times for the year 2007. The results of both qualitative and quantitative analyses of Haeundae Beach using such data are as follows: First, the comparative analysis of data on the coastal altitude from DEM and GPS surveyed data that were created using LiDAR data shows an overall deposit on the beach compared with that of the year 2005. The sections at Joseon Beach Hotel and Korea Condo to the east and west of the beach had the most deposits, while the cental part of the beach had slight erosions compared with other sections. Second, this research analyzed seasonal changes in the Haeundae Beach for a year based on the coastal monitoring data. It shows that the sections at Joseon Beach Hotel to the west had erosions in summer season and deposits in winter season, while the sections at Korea Condo to the east did opposite behaviors, which indicates the beach has been greatly affected by seasonal winds. Thirdly, from results of sectional survey, repeated sedimentation was generally found, like the bathymetric map analysis, at east and west sides of the beach sedimentation were found to occur strongly. Besides, only erosion could be found at the central parts of the beach. This may be affected by the artificial nourishment that had been conducted at the coast. This research obtained 3D spatial information using LiDAR data, coastal monitoring data, and seabed depth data, and based on it, analyzed the erosions and deposits on the shore/seabed. Beside this GIS method, as Haeundae coastal topography generates coastal erosion due to different causes resulting in a lot of sand loss, constant monitoring for the erosion areas is needed. A systematic survey on Chuncheon Stream that played the most important role in sand inflow to Haeundae Beach needs to be sought to naturally introduce the sand into the beach beside the artificial nourishment. Providing marine topographic data and costal topographic data, this study results are expected to provide useful information to the coastal management information system. Further studies to analyze long-term changes in marine topography supplementing long-term bathymetric data and to prepare a model that can estimate soils coming from Chuncheon Stream and Suyeong River may lead to more systematic study results.