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Water Resource
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Real-Time and all-weather Quasi-Real-Time Montoring
System of Remote Sensing information on the flood
dangerous state and losses
Cao shahu
The Remote Sensing Center of
The Ministry of
water Resources
Beijing, China
Abstract
This paper introduces to the remote sensing information system for real-time or all weather quasi-real-time monitoring flood, which synthesizes the application of remote sensing (technique), communication (technique), and geographic information technique. It will be helpful for the headquarter of flood control to see the flood area over thousands kilometer away from the headquarter and understand the flood level and its change. Besides, the system can investigate the losses of flood submergence quickly by using flood control database. Thus the headquarter can make the precise judgment and take emergent measure to reduce the losses in the life and property of the people.
Real-Time Monitoring System of Remote Sensing Information on the flood dangerous state and losses of the yellow river basin
- The composition of the System
The system is composed of the following two subsystems----real time transmission subsystem of aerial images and level data of flood and flood-control Database of flood detention and storage area in the Yellow River Basin.
Real - time transmission subsystem of aerial images and level data of flood consists of remote sensing plane, automatic measuring station of water-level, transition station of aerial images and level data, communication satellite and microwave relay station, receiving and recording station and processing center.
Remote sensing plane is used to trace the flood of the yellow River. On the plane, high resolution TV cameras real-aperture (8mm) side-looking radar take the images of flood level-receiver receives level data from automatic measuring station of water-level, and transmitter sends the level data and flood images to Transition Station. Moreover communication line is equipped on the plane so that the position of plane and the state of flood can be timely reported and the communication connation can be continuously kept.
The automatic measuring station of water-level, which consists of level sensor and level data transmitting device, monitors the level and its change of the test section.
The transition station receives flood images and level data from the plane, and then put them into microwave communication lines and sends them to a communication satellite respectively. Receiving device of flood images and level data, microwave communication equipment, TV transformer and small satellite ground station are equipped in the transition station.
The communication satellite and the microwave relay station are used to transmit flood images and level data real-timely and in long distance.
The processing center real -timely receives, displays and records flood images and level data of the yellow communication lines, and put them into computer image processing system, which can process them and output the results. The equipment of the center include: receiving device which receives flood images of the Yellow River transmitted to Beijing by the microwave communication lines, satellite ground station which receives flood images and level data transmitted to Beijing by communication satellite relay, and transformer, display device, video recorder, computer image processing system and the like.
The receiving and recording station has TV set and video recorder.
Flood-control database of flood detention and storage area must be in advance established, so that the losses can be quickly calculated by using real -time transmission subsystem of flood images and level data when the Yellow River in flooded. A great amount of information about natural and social economics in flood-plain and detention and storage areas are digitized and put into computer. Special management software has been studied. The data of flood-control database include height, land -use state, settlement and social economic data, because height data are essential to determination of submergence scope and water depth and the data of land-use state, settlement and social economic data, because height data are essential to determination of submergence scope and water depth and the data of land-use state, settlement and social economics are necessary for calculation of losses. Height data are acquired by sampling from topographic maps (1:10,000) according to the grid of 100mx 100m. In order to acquire the newest land-use state data, we specially took aerial colour infrared images before the flood of this year, complied land-use state map (1:50,000) based on visual interpretation of them, and finally got land-use data by digitizing the land-use state map. Settlement and social economic data, which are generally point distributive, are collected by using topographic maps (1:5-0,000) and social economic investigation information concerned (lack in the data of factory-enterprises). The total flood-control data in this test are near 4,000,000. Moreover, we have studied the programs of data input, storage, revision retrieval, statistics, form composition and graphic display and output, etc.
- Introduction to the Test
We got great successes in this test of the system on August 22, 1988. While the plane flys above the Yellow River, sensor takes flood images and level receiver receives flood level data from the automatic measuring station of water-level. Transmitter on the plane sends the remote sensing images and level data to Liutun transition, where they are divided in to two channels
to be transmitted in long distance. In one channel, images and level data are transmitted to the satellite 5 of the International Communication Organization, and sent to Yungang communication satellite main station in Beijing by the satellite.
After signals are enhanced, the Remote Sensing Center of the Ministry of Water Resources receives displays and processes them. Because of the limitation of signal-channel width of communication satellite used in this year, stationary images and level data of flood are transmitted to Beijing. In the other channel, flood images are transmitted to CCTV through the microwave communication lines of the Broadcasting and Television Department of Henan Province and the Post Ministry, and then are sent to the Remote Sensing Center of the Ministry of Water Resources through the microwave communication line from CCTV to the Ministry of Water Resources. When the images of flood in the channel are transmitted to Zhengzhou, the Television Station of images of flood in the channel are transmitted to Zhenghou, the Television Station of Henan Province televises them by the ninth frequency channel. Therefore, the Water conservancy Committee of the Yellow River can real-timely receive and record the flood images. The flood images transmitted to Beijing can be put into computer within 3 seconds.
The images, which have been processed, can be output in hardcopy within 75 seconds. The submergence scope and losses can be retrieved in flood-control database by using level data or one village name on the flood boundary line, and submergence scope map and Chinese and English loss tables can be quickly output, thereby the level data of flood, submergence scope and losses can be quickly output, thereby the level data of flood, submergence scope and loses can be quickly provided to the flood-control command departments. The deference is 2.9 percent between the losses retrieved in flood-control database by using real-time flood image around Zhongwanzhuang and Outan one day of 1988 and ones investigated by the Water Conservancy Committee of Yellow River in the field of the same day we are satisfied with the result.
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