2011IGARSS_coastline_20110726.pptx
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Transcript of 2011IGARSS_coastline_20110726.pptx
OBSERVATIONS OF COASTAL CHANGES ON TAIWAN USING A 10 YEARS TIME SERIES ERS
SAR IMAGESHsiu-Wen Wang, Kun-Shan Chen, and Chih-Tien Wang
Institue of Space Science & Center for Space and Remote Sensing Research, National Central University
Chung-Li, Taiwan
OutlineINTRODUCTION
DATA AND METHOD
VALIDATION
OBSERVATIONS AND
RESULTS
DISCUSSIONS
CONCLUSION
INTRODUCTIONEsat China Sea longshore current
South Sea of current of seasonal winds
The structure for western coast is mainly sandy shore, while eastern
coast mainly rocky shore.Characteristics of ocean currents surround
Taiwan
Kuro
shio
DATA AND METHOD (1/3)ERS-1&2 SAR Images SPOT-2&5 Images
2007/07/23
2007/08/23
1997/10/24
1. 2 times observation data set of 1997 and 2007
2. Same tidal datum.3. Cloud-free images
Trac
k
Range
Local Time: 10:30 a.m.Tidal station
1. 55 times observation data set of 1996, 1999, 2003, 2005, and 2010
2. descending orbits
DATA AND METHOD(2/3)1996/01/31 Waisanting
ERS-1 SAR image
1996/01/31 WaisantingWaterline
FilteredSAR images
Average filter
w1xw1
Average filter
w2xw2
Average filter
w3xw3
Edge detection Edge detection Edge detection
waterline
correlator
Multi-scale edge detection
Red Green Near infrared
Shortwave infrared
Panchromatic Fusion
Fusion band 1
Edge detection
Correlator operation
waterline
DATA AND METHODS(3/3)
Red Green
NIR SWIR
Fusion Red Fusion Green
Fusion NIR Fusion SWIR
Multi-scale edge detection
Image data: ERS-2Local time: 2007/04/19 a.m. 10:30Location: Waisanting sandbank in Chayi county
under 10
11-20 21-40 41-600
102030405060
22
57
17
4
GPS vs. Waterline Extraction
Difference(m)
coun
t(%
)
Waterline extraction from SAR imageWaterline indication survey from GPS
RMS: 23m
VALIDATION(1/3)
VALIDATION(2/3)
R: 2003/10/02 G: 2003/07/24B: 2003/04/10
Waterline overlaid on a color composite SAR image in 2003
Depth data integration from sonar measurement on July, 2003
Survey MarkReference pointWaterline extraction from SPOT-5
2(0.5m)
3(0.5m)
4(2.5m)
5(1m)
6(2.5m)
1(0.5m)
Image data: SPOT-5Local time: 2008/09/06 a.m. 10:14~10:17Location: Da-Fu coastline in Yilan county
RMS: 1.5m
Datum: TWD97 E N HLand
administration, M.O.I. (station:
2080)
332369.52
2742704.52 23.26
Measurement result
(AM.9:00~AM.12:00)
332369.54
2742704.55 23.34
Measurement error -0.02 -0.03 -0.08
VALIDATION(3/3)
OBSERVATIONS AND RESULTS(1/7)
Western coastline from SAR image extraction in 1996 to 2005
Eastern coastline from SPOT image extraction in 1997 and 2007
OBSERVATIONS AND RESULTS(2/7)
Nanliao
Siangshan wetland
Fangyuan
OBSERVATIONS AND RESULTS(3/7)
Haifengdaosandbank
Waisantingsankbank
Yunlin offshore industrial park
OBSERVATIONS AND RESULTS(4/7)
Chigu lagoon
Kaohsiung
OBSERVATIONS AND RESULTS(5/7)
Gongliao beach
Wushin port
OBSERVATIONS AND RESULTS(6/7)2004年 12月 06日 11時 2004年 12月 06日 11時2002/05/16 a.m.12:00
The northward shore at Wushin port The southward shore at Wushin port
OBSERVATIONS AND RESULTS(7/7)
Hualien port
Chihpen
DISCUSSIONS(1/2)
Data
Tide statio
n Haifengdao
Tide(m)
Area(ha.)
Erode or heap(ha.)
Distance
1996/4/11(11:00)
-0.64 1380 - -
1999/8/19(10:30)
-0.67 2173 793 500
2004/1/15(13:24)
-0.7 1681 -492 2000
2005/7/28(10:00)
-0.62 1400 -281 100
2010/9/30(10:30)
-0.57 1750 350 500
1996 1998 2000 2002 2004 2006 2008 20101000
2000
3000
:實
際觀
測面
積公
頃
年份1996 1998 2000 2002 2004 2006 2008 2010
0
2000
4000
:累
積距
離變
化公
尺
Haifengdao sandbar change between 1996 and 2010
Haifengdaosandbank
Yunlin offshore industrial park
Juoshui River
Year
Are
a o
f sa
nd
ban
k (
ha.)
Accu
mu
latio
n d
istan
ce(m
ete
r)
Data
Tide station Waisating Sandbar
Tide(m) Area(ha.) Erode or heap(ha.) Distance
1996/10/3(10:30)
0.25 2340 - -
1999/5/6(10:30)
0.15 1673 -667 90
2004/4/29(10:30)
-0.04 1636 -37 320
2005/4/14(10:30)
0.062 1400 -236 100
2010/4/8(10:30)
0.06 1568 168 300
Waisanting sandbar change state from 1996 and 2010
1996 1998 2000 2002 2004 2006 2008 20101400
1600
1800
2000
2200
2400
:實
際觀
測面
積公
頃
年份1996 1998 2000 2002 2004 2006 2008 2010
0
200
400
600
800
1000
:累
積距
離變
化公
尺
Waisantingsankbank
Year
Are
a o
f sa
nd
ban
k (
ha.)
Accu
mu
latio
n d
istan
ce(m
ete
r)
DISCUSSIONS(2/2)
CONCLUSIONWestern coastline changes greatly while relatively small in
Eastern coast. The time series observations by SAR images clearly reveals
exposed or submerged sandbank size and moving distance of the coastline change situation
Optical image for a long time observation limits to small areas.
Sandbank waterline and depth data integration was verified and the data can be used for inter-tidal zones estimation.
satellite remote sensing by SAR, aided by ground tidal data, bathymetric mapping, and optical images, is an effective and efficient tool for mapping the changes of coastlines and sandbanks over long periods of time.