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