Analysis of bar morphology using multi-temporal and multi-sensor satellite images: Example from the Han Estuary, Korea

Abstract

In the present paper, we report a new powerful technique of studying bar morphology using multi-sensor and multi-temporal satellite images with examples from the inaccessible field sites of the Han Estuary in Korea. The technique utilizes the ability of multi-spectral optical sensors for classifying the types of land cover, and the ability of synthetic aperture radar (SAR) for acquiring radar imagery during day and night, irrespective of cloud cover. Combining the data acquired by both types of sensors at different times, the bar morphology of the Han Estuary is analyzed in this study. The Han Estuary is situated on the North Limit Line (NNL) dividing North and South Korea, and considered to have retained its rich ecological value. However, because of the limited access to the estuary, little information is available on the morphology of the Han Estuary, and the technique based on satellite remote sensing described in this paper is the most suitable and only approach to obtaining information on such inaccessible areas. In the present paper, the bar morphology of the Han Estuary from the years 2000 to 2009 is investigated using multi-temporal spaceborne optical sensors including those on board of SPOT-5, LANDSAT-7. QuickBird, KOMPSAT-2, and OrbView-3, and also C-band synthetic aperture radar (SAR) on board of RADARSAT-1 and ENVISAT with limited field survey data. Sixteen sets of optical data and twelve sets of SAR data were used to study the spatial and temporal variations of bar morphology and the effects of tide and precipitation. The results show that there was some variation in shape and size of bars depending on the location. The tidal effect is large on the bars closer to the open Yellow Sea, and the effect of precipitation was observed on the bars located in the mouths of rivers. Based on the changes of the bar water boundary, a topographical map was produced, showing the relative height of bars. Using the technique of satellite remote sensing, this paper has shown, for the first time, the long-term bar morphological characteristics of the restricted Han Estuary on the NLL, and the authors anticipate that the results together with the relative height map of bars will constitute the basis of future morphological and ecological studies in this important estuary. (C) 2012 Elsevier B.V. All rights reserved.