Monitoring of topographic change on the coastal area Jinah Eom 1,2, Jong-Kuk Choi 1, Joo-Hyung Ryu 1, Joong-Sun Won 2 1 Korea Ocean Satellite Center, Korea Ocean Research & Development Institute 2 Department of Earth System Sciences, Yonsei University

Contents 1. Introduction & Objective 2. Study area 4. Results 5. Conclusion 3. Data & Method

1. Introduction

 Since the 1980’s, a series of construction projects for land reclamation have been carried out on a large scale in western sea  Land reclamation combined with the dynamics of tidal currents accelerated local sedimentation and erosion, resulting in the fast reformation of intertidal topography  For this reason, Lee et al (2006), Ryu et al (2008), and so on were carried out monitoring of tidal flat topography using Digital Elevation Model (Lee et al, 2011)

1. Introduction  The Nakdong River Estuary Barrage (NREB) was constructed in 1987 to prevent saltwater intrusion and to provide the sustainable water supply in the upstream channel of the NREB.  Fluvial changes and sedimentation problems have been continued due to urbanization and development in the watershed as well as construction and management (sediment dredging) of the NREB

1. Introduction

 The importance of the east sea to key industries, such as nuclear power plants, shipyards, and cement production, and to a lesser extent the fishing and leisure industries, is gradually increasing  However, coastal erosion in east sea is being accelerated so that the size of the sandy beach is being reduced abruptly along with a lots of other places including Jugbyeon, Bongpyeong beach, Sanpo-ri, Weonnam, Osan, Deogsin, and Hupo in Uljin-gun.

Objective Long-term monitoring using remotely sensed data Observed a topography through survey Propose integrated management methods for the utilization and preservation of coastal seas in the near future Final goal In this study

2. Study area

3. Data  Remotely sensed data Change of sandbar : used Landsat ETM+ image from 2002 to 2010 Monitoring of shoreline change : used aerial photograph, IKONOS, KOMPSAT-1/2 from 1971 to 2009 Monitoring of topography : used aerial LiDAR data and terrestrial LiDAR at 2008, 2010  In situ data – used DGPS Date : May , Jun For comparison with Lidar data

Location of 2 nd grade measurement survey benchmarks within KORDI-ESRI

Method –extract line  Extracted shoreline and sandbar estimate the reflectance of sand and sea dry sand reflectance is very strong Near 750 nm : sea is absorption but sand is reflectance  Sea is dark color but sand is bright color  used NIR band

Method – LiDAR DEM  LiDAR – generated DEM data DEM change = DEM 2008 – DEM 2010 DEM change : topographical change DEM 2008 : topographical height in 2008 DEM 2010 : topographical height in 2010 Positive : represents erosion Negative : sedimentation

Results 1 - sandbar Nakdong River Estuary Barrage (NREB) was constructed in 1987 After that, current rate and sedimentation rate were changed Nakdong river is a major source of sedimentation of sandbar Tide height : 68 cm : 71 cm