August 25, 2005 Kuo-Hsin Hsiao, Jin-King Liu, Ming-Fong Yu Speaker : Kuo-Hsin Hsiao Identification of Landslides with combined RS and GIS data

1. Introduction 2. Landslide Detection 3. Results of landslide interpretation 4. Concluding Remarks List of Contents

1. Introduction ◆ Geologic and terrain characteristics in TAIWAN ◆ Climate condition – typhoon, torrential rainfall ◆ R.S. data – spatial 、 temporal resolution resolution, data acquisition, time required for interpretation, combined information of GIS, etc. Highly fractured rock formations Variations of Geologic Conditions: A section across Taiwan Lithology- conglomerates

Requirement of A Monitoring and Early Warning System Both for Emergency Response and for Mitigation Policy Landslide Detection Using Satellite Images –High Frequency Periodic Observation and Measurements : Month~Year –Data : SPOT-5 or Formosat-2. Objectives of the study: Periodic landslide Monitoring for Sustainable Management using high resolution data (for detecting small landslides) Prevention of Illegal Land Use and Deterioration Disaster Damage Estimation Background Orbit of FORMOSAT-2 Sun-Synchronous Orbit Altitude = 891 km; Inclination = deg; Period = 14 Rev/day Introduction

Research Area: Shihmen Reservoir Introduction SPOT image flight path (CSRSR)

Shihmen Reservoir Purpose of the Reservoir –General water supply –Irrigation –High-tech industry Watershed Area:764 KM 2 Capacity: 2.5 x 10 8 M 3 Terrain Variation : 252M~3,500 M Average Rain Fall : 2,500 mm/yr Land-Use Type –Coniferous Tree, Deciduous Tree –Orchard, Rice, Village, Farming, Foresting –Bare Soil, River, Mixed-Forest, Bamboo, Grass Land –Mixed Coniferous-Deciduous Tree, Others. Land-Use Coverage Introduction

Shihmen Reservoir Introduction DEM slope forest type Soil map

Disaster – Typhoon AERE Duration : –Aug. 23 ~ Aug. 25, 2004 Maximum total accumulative rain fall -1,600 mm Maximum rain fall –146 mm / hr Contour of Total Accumulative Rain Fall : :23 Introduction CWB

Water Quality after Typhoon Introduction 2004/8/26 FORMOSAT-2 Satellite IR Typhoon Road of AERE High turbidity Satellite Radar NSPO CWB

2. Landslides Detection SPOT /08/16 Resolution ： 10m SPOT5 2005/03/16 Resolution ： 2.5m & 10m Formosa-II 2005/04/04 Resolution ： 2m & 8m Data Acquisition

Disaster Estimation & Analysis Processes Disaster Estimation Disaster Areas DTM + Image (3D Visualization) Overlay Analysis Day-1 Image Day-2 Image NDVI/CVA Change Detection Landslide C overage Change ? YES NO Stop On-Site Photography Landslides Detection Classification overlay

Various Types of Landcover and Landuses Landslides Detection (a)River-bank landslides (b)Slope landslides (c)Upstream landslides (d) snow on tops (e)Grass lands (f)Excavated lands (g)Cultivated lands (h)Mountain village (i)Plain villages (j) Cemetery (k)Roads (l)Rivers

SPOT-5 data acquisition (before & after AERE) Landslides Spatial resolution Total No.Area (ha) Before typhoon (2004/08/16) m*10m Afetr typhoon (2005/03/16) m*10m 3. Results of landslide interpretation

Results Landslide interpreted from SPOT5 10m & 2.5m Acquisition date Landslide Spatial resolution Total No.Area (ha) SPOT5(2005/03/16) m*10m m*2.5m Spatial resolution : 10mSpatial resolution : 2.5m

Results Landslide interpreted from formosat2 8m & 2m Acquisition date Landslide Spatial resolution Total No.Area (ha) Formosat-2(2005/04/04) m*8m m*2m Spatial resolution : 8mSpatial resolution : 2m

Results Landslide interpreted from Spot 10m & formosat2 8m Acquisition date Landslide Spatial resolution Total No.Area (ha) SPOT5(2005/03/16) m*10m Formosat2 (2005/04/04) m*8m Spatial resolution : 10mSpatial resolution : 8m

Results Landslide interpreted from Spot 2.5m & formosat2 2m Acquisition date landslide Spatial resolution Total No.Area (ha) SPOT5(2005/03/16) m*2.5m Formosat2 (2005/04/04) m*2m Spatial resolution : 2.5mSpatial resolution :2m

Statistical analysis Results

3D Visualization of Detected Landslides Red regions denote the detected landslides of Formosat-2 test data. Landslide induced by typhoon AERE Results SPOT-5(2004/08/16) SPOT-5(2005/03/16) On-Site Photography SPOT-5(2004/08/16) SPOT-5(2005/03/16) On-Site Photography CSRSR

SPOT-5(2004/08/16)SPOT-5(2005/03/16) On-Site Photography SPOT-5(2004/08/16)SPOT-5(2005/03/16) Helicopter Photography Landslide induced by typhoon AERE Results CSRSR

Formosat-2 image SPOT image Flight Simulation after NERE Typhoon 2004/8/31 (NSPO) After typhoon NERE 2003/11/14 Before typhoon NERE

Comparison with Existing Landslides in GIS database also with Cadastral Informations

Conclusions Requirements of A Monitoring and Early Warning System –Bottleneck--Data Acquisition High frequency data acquisition of remote sensing. Near Real-time Dynamic Monitoring… Typhoon AERE –Statistics 477 & 473 places, total areas of & hectares of landslides were detected using SPOT-5 and Formosat-2 fusion data The reliability of landslide detection is high when comparing with on-site photography.

Conclusions –With Formosat-2, A Possibility of Near real- time disaster estimation Provide disaster information in a short time. Historical data collection is important. A comparison can be made by GIS database. Construction of GIS database infrastructure is critical for post-disaster analysis.

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