International Archives of Photogrammetry and Remote Sensing. Vol. XXXII Part 7C2, UNISPACE III, Vienna, 1999
126
I5PR5
UNISPACE III - ISPRS/EARSeL Workshop on
“Remote Sensing for the Detection, Monitoring
and Mitigation of Natural Disasters”
2:30-5:30 pm, 22 July 1999, VIC Room B
Vienna, Austria
APPLICATION OF«4D» TECHNIQUES IN FLOOD MONITORING IN CHINA 1998
Liangcai Chu, Ziwei Li, Yutong Liu
Chinese Academy of Surveying and Mapping
Beijing, 100039, P.R. China
KEYWORDS: Natural disasters, remote sensing, flood monitoring. DEM. 4-D techniques
INTRODUCTION
4D is produced by combining modem remote sensing and GIS
technology and fonns the basic mode of digitized products for
surveying and mapping. It includes a Digital Elevation Model
(DEMDE), Digital OrthoQuards Qu (DOQDO), Digital Raster
Grapliics (DRGDR) and Digital Thematic Information (DT1DT).
A 4D flood-protection technical institution was established
including; a remote sensing helicopter, a 4D-background
database of potential disaster areas and a data management
system, a flood prediction and risk assessment service system,
topographic maps in a background database and a dynamic
monitoring system of land-use. This institution was active
during the floods in 1998 resulting in detailed flood monitoring
and assessment that were provided to the decision-making
department and provincial government. The following tasks were
performed:
1. Prediction of potential flood areas and water volume at
various water levels.
2. Acquisition of infrared color images of important cities of
Dongting-lake and Poyang-lake areas at the highest water
level.
3. Statistics of flood range and flood area in the same areas at
the highest water level.
4. Compilation of an atlas of risk zones in the areas during the
1998 super flood.
5. Video tape monitoring of the flood.
6. Reconstruction homestead including an updated
topographic map for YangZi river and NenJiang river.
METHODOLOGY
Remote sensing monitoring by helicopter at low-altitude
This system includes a Mig-8 helicopter with GPS navigation
positional system, light aerial optical measurement camera, CCD
digital camera and digital VCR. The system was used over the
Dongting and Poyang lakes from I s * Aug, 1998 to 10 th , i.e.
during the most dangerous period, flying under the clouds
between raining days. Data was obtained as listed below:
• Black and white aerial photo of the two lakes at 1: 8000
scale.
• Color infrared aerial photo important cities at 1:8000 scale.
• GPS data record for flight tracks
• VCR tapes from aerial camera
• 300 color pictures of low lakes
4D background database of potential disaster environment
and data management system.
The content of the database is listed below:
Digital Orthquard database-, created by using 1:35000 new
aerial photos and SPOT panchromatic image
Digital Raster Graphics database: created using 1: 10000, 1:
50000 new topographic maps.
High accuracy Digital Elevation Model database: digitized
from new 1:10000 contour line for topographic maps. The
resolution is 5 meters and the accuracy in plane regions is 0.5
metre; in mountainous areas tire accuracy' is 2.5 metres to 5
metres.
Digital Thematic Information database includes:
• Land-use classification data
• Boundary data, road and embankment data in vector version
• Important point data including location for government,
density' habitat, large factories
• And mines
• Hydrological Station information
• Population and economy information
• Flood protection engineering information
The database is in 1:50000 scale and most data is in a raster
format also compatible with vector data, statistical data and
report text data. The software was developed for an ARC/INFO
platform with functions including registering, queiving,
displaying and overprinting. All data can be managed in
normalizing way with spatial positioning.
POTENTIAL APPLICATIONS
Flood forecasting and loss assessment service system
This system offers several methods of selection to different
scales to compile map sheets of counties, enclosing-dikes and the
whole region. Supported by 4D background data, the system
quickly constructs maps of flood submerging range, place, area,
water depth water accumulation volume and economic losses. It
