Frontier of Environmental Science September 2013, Volume 2, Issue 3, PP.17-23
Space-Earth Integration Observation Based Environmental Emergency Monitoring and Management System Design Tao Xie 1,2â€ , Rui Liu 1,3, Qiuhong Hu 1 1. Institute of Resources and Environment Science, MAPUNI, Beijing 100101, China 2. Department of Environmental Science and Technology, College of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029, China 3. School of Geography, Beijing Normal University, Beijing 100875, China â€
Abstract It is of great significance both practically and theoretically to establish an environmental emergency monitoring and management system based on space-earth integration observation and to enhance the ability for environmental risk prevention and emergency response. Based on the analysis of development of environmental emergency system in China, the present study discussed the system framework and software functions of the space-earth based integrated environmental emergency monitoring and management system. Emphasis was especially put on the function improvements caused by introducing UAV-based environmental emergency monitoring system. In addition, the relevant key technology choices with regard to sensor, space-earth data analysis and real-time data transmission technique were analyzed from the perspective of present situation, difficulties and development trend. It is expected to provide some beneficial reference for the establishment of modern environmental emergency system. Keywords: Environmental Emergency; Environmental Monitoring; Unmanned Aerial Vehicle (UAV) Platform
1 Introduction With rapid development of industrial economy, hazardous chemicals have experienced a rapid growth in either category or quantity. Meanwhile, abrupt environmental accident due to their unsound safety production, management, storage, transportation or usage also presents an increasing trend . Environmental emergency monitoring plays an especial important role for environmental abrupt accident emergency response. It can obtain on-site dynamic information about category, pollutants concentration distribution, influence scope and developmental trend of the accident for government departments, and win precious time for rapid and accurate emergency decision making, so as to effectively control pollution scope, shorten the duration time and finally minimize the loss of the accident. Consequently, research on emergency environmental monitoring is urgently needed. However, manual monitoring method based on single-point sampling and analyzing remains mostly used environmental emergency monitoring method in China . This method is slow, inefficient and always limited by ground conditions, traffic conditions and monitoring conditions. In the implementation of environmental emergency monitoring, the manual monitoring method is sometimes unable to obtain timely and comprehensive distribution of pollution sources, types of pollutants, contamination, pollution range, pollution area, duration, diffusion and migration, the scope and extent of effect . All of these may delay the disposal of pollution incidents and reduce the pollution incident processing efficiency. Developing effective emergency monitoring tools, building responsive, efficient and convenient system of pollution incidents monitoring and warning - 17 http://www.ivypub.org/fes
technology are essential to improve the ability of responding sudden environmental pollution accidents Compared with traditional environmental emergency monitoring system with environmental emergency monitoring vehicle and portable gas detection devices as the mainstay, Unmanned Aerial Vehicle ( UAV ) platform based atmospheric environmental emergency monitoring system has such advantages as real-time, flexibility, high-resolution, low cost, and collecting information in dangerous environments without risk, which provide a new option for emergency monitoring to deal with the abrupt atmospheric pollution accident, as well as opening up new branches[4-15]. As an important complement, it will be integrated with traditional systems. However, in present, the construction of relevant system is still in the research stage. Although some of the achievements has had the ability of commission [4-5], test is still needed with regard to cost, work capacity and benefit. In our study, combined with the actual needs of the environmental emergency management based on space-earth integration observation, the framework of environmental emergency monitoring and management system was demonstrated and a preliminary functional design was conducted to explore the options of key technologies in the system. The environmental emergency monitoring and management system may be a beneficial reference for the establishment of modern environmental emergency system.
2 Methodology 2.1 System architecture design As shown in Figure 1, space-earth integration observation based environmental emergency monitoring and management system mainly consist of 3 systems and 3 platforms, which are information management, information standards and information security system, basic support, data support and application services platform respectively, in which the basic support platform refers to two parts, e.g. emergency command center (fixed emergency platform) and on-site emergency command platform (mobile emergency platform). UAV-based environmental emergency monitoring system, as an important component of on-site emergency command platform can obtain the geography, resources, environment and other space remote sensing information in a quick way, which are important source of comprehensive database of environmental emergency in supporting the construction of the application service system, especially the development of mobile emergency system in emergency command vehicle.
Environmental risk information management system
Environmental risk monitorcontrol and early warning system
Environmental emergency monitoring system
Decision Support System
Fixed Emergency comprehensive database
Information management system
Hazardous chemical data
Risk source data
Accident spatial analysis
Satellite receiving terminal
Information security system
Accident dispersion modeling
Environmental emergency monitoring data
Mobile emergency platform
Fixed emergency platform
afterward evaluation system
Communicatio ns network
Emergency Command Vehicle / UAV monitor and control Vehicle
Information standards system FIGURE 1 ARCHITECTURE OF THE SPACE-EARTH BASED ENVIRONMENTAL EMERGENCY MONITORING AND MANAGEMENT SYSTEM - 18 http://www.ivypub.org/fes
2.2 Hardware structure of the UAV platform based environmental emergency monitoring subsystem As the key component of the environmental emergency monitoring and management system, the hardware structure of the UAV platform based environmental emergency monitoring subsystem is shown in Fig.2.
FIGURE 2 HARDWARE STRUCTURE OF THE UAV PLATFORM BASED ATMOSPHERIC ENVIRONMENTAL EMERGENCY MONITORING SUBSYSTEM
The core of a UAV platform is the flight control system, which consists of flight control computer, navigation and positioning computer, airborne sensors groups, servomechanism and airborne power supply system. The composition of the flight control and navigation system is shown in Fig. 3: Data storage
Data link terminal
Flight control system Flight control
FIGURE 3 COMPOSITION OF THE FLIGHT CONTROL AND NAVIGATION SYSTEM
The airborne monitoring devices of the UAV platform based environmental emergency monitoring system include: environmental monitoring devices, and video or image monitoring devices. There are mainly two kinds of devices: two-dimensional planar aerial photography based spectrum device (such as thermal infrared imager, the light infrared aerial sweep instrument, infrared scanners, microwave radiometer, etc.) and the pump suction punctate sampling based airborne gas monitoring device (such as particle detectors, differential optical absorption spectroscopy detection systems, the electrochemical gas monitoring devices, etc.).
3 System function 3.1 Functional Overview Traditional environmental emergency monitoring and management system includes the following sections:1) basic information management system centered by management of environment risk source, 2)environmental risk monitor-control and early-warning system with on-site monitoring as its core; 3) environmental emergency monitoring System focusing on on-site emergency monitoring equipment, methods, data management and so on; 4) environmental decision support emergency system characterized by event simulation and prediction, the according solution generating of treatment and disposal, plans call and on-site dispatching; 5) accident post-evaluation system focusing on event classification, identification of pollution loss, impact assessment et al., 6) mobile emergency system emphasized on providing function of the relevant information inquiries, on-site information gathering and mobile GIS applications in the scene of the incident.
3.2 Functional improvements by introducing UAV based environmental emergency monitoring system Introducing UAV platform based environmental emergency monitoring system can greatly enhance the traditional - 19 http://www.ivypub.org/fes
one in ability and efficiency. Its function improvements can be expressed as follow: 3.2.1 Usual Application For normal applications, it is used to monitor the especially important and sensitive areas (such as drinking water sources, nature reserves et al.) through the default route flight mode, via video surveillance and image capture functions , as an useful supplement of environmental risk monitoring and control 3.2.2 Emergency Applications In the abrupt environmental accidents, UAV based environmental emergency system is mainly used for emergency on-site monitoring and decision support. The function is as follow: (1)Toxic gas monitoring system The main achievement of toxic and hazardous gas monitoring subsystem is dynamic display, process and analysis of gas monitoring data, including real-time data view, high concentration alarm, statistical analysis, report output et al. For multi-point monitoring data, the gas concentration distribution is also able to be displayed based on three-dimensional GIS platform and the sampling point coordinates. (2) Video monitoring subsystem Functions of video monitoring subsystem include: remote control of video surveillance devices, shooting angles, focal length etc.; video monitoring information display in real-time in ground stations; call a professional image stitching software to interrelate all the overlapping images in the video stream, so as to generate a seamless, clear and image in real time with an expanding visual field by preprocessing, registering and splicing. Specific way to achieve: firstly, to obtain real-time video image through a video capture device, and then de-frame; secondly, to preprocess every frame video image in the way such as histogram equalization and edge extraction; thirdly, making use of the correlation among images to register and then stitch them to form a panoramic image of the big visual field . (3)The emergency assistance decision making subsystem In this part, according to the needs of abrupt atmospheric environmental emergency accident, functions like hazardous chemical information management, simulation analysis of atmospheric pollution diffusion, emergency response preparedness management, emergency monitoring handbooks et al. are provided, which are based on atmospheric monitoring information.
4 Discussion 4.1 Airborne environmental emergency monitoring devices selection Airborne environmental emergency monitoring devices mainly include video recorders, cameras and portable gas and water quality detection devices. The technology of recorders and cameras has been well studied and made many progress in high resolution, multispectral, large plane array and digitizing [7-10]. For example, the resolution of general digital camera can reach 10 million pixels or more, such as the Cannon 5D Mark â…Ą, Cannon EOS 5D, Cannon EOS 300D, Cannon EOS 4500D etc. The exiting technology and products can effectively support the application of UVA environmental emergency monitoring system. However, light-weight, miniaturization of airborne equipment and high quality devices for gas and water quality monitoring is a big challenge for the further development of the system. 1) In water quality monitoring, spectral devices based on two-dimensional planar aerial photography operation mode, such as thermal infrared imager, light infrared air sweeping instrument, infrared scanners, microwave radiometers et al., are commonly used for water pollution monitoring in macroscopic scale. Specifically, the alternative devices include: airborne high resolution radiometer designed by national space science center of the Chinese academy of sciences and compact multispectral imager made in Shanghai institute of technical physics of the Chinese academy of sciences. Of them, the airborne high resolution radiometer is an x-band microwave - 20 http://www.ivypub.org/fes
radiometer with the spatial resolution of 2 degrees and can obtain high resolution radiation brightness temperature images of ground objects. By interpretation and inversion of them, the lake, ice, revers, swamps, land and other landmark information can be gotten. While the compact multispectral imager is a device using CCD array elements and having four bands, e.g. red, green, blue and near-infrared. It can be used in detection of marine pollution, sea ice, oil spill, red tide et al. 2) At present, the UAV remote sensing technology of atmospheric environmental monitoring in the domesticoriented field is still in the primary stage and the research for the miniaturization, lighter types of airborne special monitoring devices development is also in an emerging field. While the research for the airborne devices developed abroad using remote sensing fourier transform infrared spectroscopy (RS-FTIR) has entered a mature application stage, such as the titan gas analyzer developed by MIDAC (U.S), which achieved the integration of airborne operations and atmospheric environmental monitoring data processing. These high-cost devices with large volume and quality, will have high requirements for the stability of the UAV platform and payload, and have not been widely used in the country currently. The domestic research and development for the devices of aviation measuring aerosol that suitable for low-altitude, low-temperature, low-pressure environment conditions has been launched. There are some advantages of small, lightweight, quick measurement and low devices investment for the atmospheric environmental monitoring devices which was based on gas sensor development, taking airborne transformation for this type of devices and performance testing for the UAV telemetry. In case of less precision for emergency monitoring, it is also a viable option for a low cost at this stage. Especially the atmospheric environmental monitoring devices that based on the sensor array technology with gas recognition function, there would be better prospects for the application of quantitative discrimination and measurement during the process of emergency monitoring.
4.2 Data analysis technology (1)Space-earth data assimilation technology Data Assimilation is a method that based on considering the data temporal-spatial distribution and estimating the deviation of the model and observation and reconcile new observed data at the time when the numerical model is running, the aim is to obtain the data set which has uniformity of time, space and physics . The key technique of constructing space-earth integration environmental emergency monitoring and management system is how to integrate stereo and ground monitoring of unmanned aerial vehicle, solve the disunity problem of resolution ratio during the process of reconciling. Data Assimilation is a kind of data processing technique of multi-source data and model data setting, the usual Data Assimilation method include the variational adjoint method, Kalman filtering method, direct minimization method, the random algorithm assimilation method and so on [11-12]. But the research of space-earth integration assimilation method aimed at data collecting characteristic of unmanned aerial vehicle is short and also need further improved. (2) Video image stitching technology High-speed and effective video image stitching technology is the key to obtain accident information rapidly. As the image quality usually affected by the UAV flight condition, it is difficult to meet the traditional requirements of aerial triangulation entirely. Therefore, traditional aerial photography could not be totally used in the UAV images processing. In the absence of other control point data, how to match, splice and correct UAV images rapidly only using secondary data of UAV images and the UAV system themselves has become the hot spot in research field of UAV based remote sensing [13-15]. Related studies show that SIFT algorithm has better prospects in this process . However, there are still none mature system for image processing currently and the interrelated processing software is also rare. Great efforts are still needed for relevant research and mature product of software system.
4.3 Communication insurance technology In the space-earth integration based environmental emergency monitoring network, great efforts will be made to obtain real time environmental monitor and control information from accident scene by comprehensively applying - 21 http://www.ivypub.org/fes
various of communication means, and then the according information gotten will be sent to commanding platform at the scene and emergency control and command platform located in the environmental protection department to support decision-making analysis. Consequently, the emergency response speed could be improved greatly. At present stage, considering environmental emergency capacity building of our country, system structure of emergency communication may refer to Fig 2. Its advantages are shown in the following aspects: 1) emergency command vehicle and ground control vehicle of UAV is made into integration, which can be used as communication command platform as well as achieving the function of commanding UAV system and data collection and analysis from airborne environmental emergency monitoring devices. Therefore vehicle is used in an intensive way. 2) Emergency command center gets information through the receiving terminal of satellite and ground network, achieving command center and emergency scene linkage. In addition, the communication way of 3G is also an alternative. Generally, the information communication between emergency scene and command center is achieved through 3G mode, which can decrease the cost of communication depending only on satellite. 3) The communication between single pawn at emergency scene and UAV monitor and control system usually uses microwave because of its good anti-disaster ability. Satellite communications Satellite communi cations
Microwave communica tion
Satellite communi cations
Emergency command vehical/UAV monitorcontrol vehical
3G communic ations
Microwave communica tion
Information receiving terminal of saterllite
CDMA/GSM/ GPRS base station
walkietalkie command center
FIGURE 4 NETWORK TOPOLOGY STRUCTURE
5 Conclusion The construction of space-earth Integration observation based environmental emergency monitoring and management system is of great practical significance and theoretical value to enhance China's environmental risk prevention capabilities and emergency response capabilities. This article aims to start a discussion and in follow-up studies key technologies related to the system will be further explored and discussed. While the UAV remote sensing technology continues to mature in the field of environmental protection application, development of Space-Earth Integration Environmental pollution emergency monitoring system with operational capabilities will soon be implemented.
Acknowledgements This research was financially supported by the 2011 Program for Key International S&T Cooperation Projects (Grant NO. 2011DFA90910) of Ministry of Science and Technology of the PRC.
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Authors Tao Xie (1980-), male, born in Songzi, Hubei province, doctor, work on the field of environmental informationzation. Email: email@example.com
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