GISdevelopment.net ---> AARS ---> ACRS 1990 ---> Geology Disaster Remote Sensing in coal industry Guan Haiyan China Coal Remote Sensing Centre N0. 3, Jianxi Street, Xi' an, China P.C. 710054 Abstract Over the last ten years remote sensing techniques in China coal industry have been developed rapidly. Through theoretical researches, the regularity of thermal radiation and differential of optical reflectance of coal seams have been found. The correlativity between ground observational data and space image data has been discovered. During method test, a Test Area for coal remote prehensive test conducted, the suitable fields and the optimal procedure for application of remote sensing technique in coal industry determined. The theories and methods established in the researches have been applied in the practical production in respect to coal field general investigation, prediction, coal reconnaissance, coal geological surveys, detecting fire, flood and pollution in coal mines, and have yielded remarkable economic, techniques results and social benefits. This paper describes mainly the theory, methods, and practical results for coal remote sensing. Theoretical Researches Contents of Research The study of the physical characters of coal seams in the light and thermal fields is a basic job in the coal remote sensing. Through four successive years of spectral tests, and infrared observing temperature work, a lot of data were obtained. These data were elabozated systematically in order to probe reflective character of coal seam in light field, to look for the regularity of radiation of the coal seam in the thermal field, to develop applied theories and define the criteria for applications used for coal remote sensing. Reflection Characteristics of Coal Seam in the Light Field. The Measurements show that reflectivity of coal seam within 0.5-0.8mm is less than 10%; between 0.9-0.95mm is about 12% (peak value), within 0.95-1.1mm is decreasing. Compared with other rocks, the reflectivity of the coal seams is the lowest in 0.4-1.1mm band, it's reflectivity is 5-30% lower than that of other rocks. The research proves that various photographic and scanning means of remote sensing in the light field are applicable to the recognition of coal seams and detection of coal measures. Regularities of Radiation of Coal Seams in the Thermal Fields. The light-heat conversion effect of the coal seam When the coal absorbs the solar light, the states of vibration and rotation of molecules change. In the process of such changes, light energy is converted into heat energy[2]. Coal is made of combustible substances. It has a porosity of about 8-20% and the general molecular formula is C102H78O10N2. There is a hydrogen-rich lateral chin in the structure model of the coal molecule. In the process of conversion of light energy to heat energy due to absorption of sunlight, thermal decomposition of the molecular structure of the coal and volatilization takes place, the components such as carbon; hydrogen and sulfur are oxidized successively. In the process of exition, the temperature increases gain, thus promoting redecomposition, revolatilization and reoxidation, forming light-heat-chemistry heat chain reaction and increasing the temperature of coal seams sharply. These are physic-chemical reaction characteristic of the coal seam after the sun illuminates the coal measures, and also the substantial properties of the thermal anomaly f the coal seams. The characteristic of the thermal radiation of coal seams with different deep The deep coal seam has a geothermal gradient 1-2°C[3]greater than the normal geothermal gradient. For the shallow coal seam, strong oxidation generally results in large-scale spontaneous combustion, so it constitutes the strongest thermal radiation source of the coal field: The surface coal seam interacts with the electromagnetic wave emitted by the sun while oxidation proceeds and owing to the influence of the day-night and seasons, there appears a periodic regularity of the thermal radiation for the surface coal seam. The above study shows the termal-infrared remote sensing is the optical method used for coal industry. Methodological Tests Preparation of Test Base for Coal Remote Sensing Xishan Goalfield, Taiyuan, have been selected as a test base for coal geology (1200km2), and Kailuan Coal Mine as another test base for productive coal mine (2400km2). Test Projects. Space Remote Sensing Tests Large-area tests were conducted by applying the China's Land Reconnaissance Satellite images. U.S. Landsat MSS, TM image data, France satellite data, USSR photo image and U.S. space shuttle radar scanning image. Airborne Remote Sensing Tests. The remote sensing flight tests involved 4 kinds of aircracts and more than 40 flights. It involved a series of tests by using 8 means 23 bands, such as black and white photography, colour photograph, colour infrared photograph, multiband photography, thermal infrared scanning, multispectral scanning radar scanning, and GPS space position test. Ground Tests In involved bands tests, infrared temperature measure and ground photography including black, white, colour and multiband. Digital Processing Test. Digital position processing was made by using BC-2 Analgtica plotter for remote sensing image data. By applying the I2S image processing and Intergraph Graphic Processing system with VAX 11/785 computer as its host, the digital thematica and serial maps were compiled and the Coal Remote Sensing Geograph Information System is being created. Four Colour Plate Printing Tests. By using CP-241 scanner , the remote sensing thematic map, serial map and different kinds of images were printed. Combined Test Multi-temporal airborne remote sensing. Daytime and nighttime remote sensing flight tests were made in both rainy and dry seasons in the coal field. Multidirectional remote sensing flight tests. Remote sensing flight tests were made along and across the strike of the coal measure . Flight tests by using a combination of multiple kinds if sensors. Flight tests were conducted using a combination of the Swiss RC-10, Aerial Camera and U.S. DS_1230 Double -Channel Thermal Infrared Scanner, as well a combination of the multispectral Aerial Camera and Aerial infrared Scanner. Multi-Level Space Synchronous Remote Sensing Tests These include tests of low -altitude remote sensing flights and ground synchronous observations, tests of middle-altitude remote sensing, low-altitude remote sensing flight and ground synchronous observations. Three-level space synchronous remote sensing tests have also been conducted by use of China's Land Reconnaissance satellite, aerial and ground observations. Test Results4 The results of the tests indicate that the space remote sensing data are applicable to coal field prediction; The SPOT satellite data and USSR photo-image are suitable for coal reconnaissance; The Airborne Remote Sensing is the main applied in coal industry and is applicable to exploration of coal field , design and production of coal mine. The optimal methodology, procedure for coal remote sensing work was formulated. The optimal applicable scope for coal remote sensing was determined. The colour infrared photography and thermal infrared scanning were determined to be the optimal methods. Through methods test, the remote sensing as a important methods, promote ground-based geological work to enter the stage of multi-level space comprehensive exploration. Now the normal Coal geological exploration sequence incorporates remote sensing, geophysical exploration and drilling. Applications of Results Application to Strategic Decision making of Energy Industry Coal is the main source of energy in China, accounting for 73% of total energy in China. The development of coal industry has a direct influence on the economic development. The satellite image map at the scale of 1:1,000,000 was compiled using imagery data. It covers 1,170,000 km2 and contains a coal deposits of 500,000 million tons; in north-west part of China 1:500,000 Remote Sensing Series Maps, in Shanxi Energy Base, cover area 157,000 km2 coal deposit revealed makes 30% of that in whole China. All these have provided a scientific basis for decision-making and strategic layout of the national energy industry Application to Area Geological Investigation.. The east part of China is more developed than the west. The coal resources of this part have been opened up mostly. In order to find new resources, area geological investigation was carried out by using satellite image data at the scale of. 1:500,000 and 1:200,000 to find coal-bearing sections to meet the needs of the east part. Application to Coal Field Prediction Remote sensing techniques were applied to coal field prediction within an area of 7000km2 in the the middle west of the Da Xing An ling Mountians. The interpretation of 1:200,000, 1:500,000 coal field geological iamges was carried out. 18 coal-bearing basins and four additional predicted coal-bearing areas were delineated with a predicted coal deposite of 54,000 million tons. Coal Reconnaissance and Discovery of Uneete Coal Field The geological interpretation of Uneete Basin (10000 km2) was made by means of landsat images data, 1:100,000 Remote Sensing Geological Map was compiled. After the analysis of coal bearing condition, the 3200km2 area in Uneete Basin was selected for interpretation of aerial photos used for compilation of 1:500,00 coal field geologic map. We outlined areas of distribution of the Jurassic-Cretaceous coal-bearing Bayanhua Formation, and determined the coal seam under grassland. Through drilling verifying, the reliability of remote sensing interpretation attains more than 80%. The total thickness of the workable coal seams is up to 40m, and 340 million tons of coal reserves has been found. Application to Coal Field Geological Mapping. The coal geological maps at 8 kinds of scales such as 1:500,000, 1:100,000, 1:50,000, 1:25,000, 1:10,000 1:2000 were compiled by using remote sensing techniques. Through examination, and acceptance, the quality of above maps were up to the national specification. The application of above 1:10,000, 1:5000, large scale geological maps, in 24 provinces, municipalities or autonomous regions shows the efficiency of mapping has increased by 3-7 times and the cost has been reduced by half and the extent of geological research and map accuracy have been raised on a big margin. Detection of a Fire Area of a Coal Mine. Spontaneous combustion of coal is of common occurrence in the coal fields with Jurassic coal beds in the North China, and constitutes a major geological hazard in coal mining. By means of airnorne thermal infrared scanning, we may delineate a burnt area, by using colour infrared photoyraphgy define the boundary between a burnt area and unburnt area, thus furnishing reliable information for production of coal resources, rational development and safe production of a coal mine Control of Water Burst in a Coal Mine. In 1984, an extraordinary water burst accident happened in the Fangeshuang Shaft of Kaoluan Mine, with a water flow attaining 2070m3/min. The water inundated the whole shaft and the loss was enormous. In that years three-level (space, aerial and ground) synchronous remote sensing and multi-temporal flights were carried out and combined with ground investigation. As a result, the Wangxizhuang active fault was determined to be the main water conducts for water gushing in the shaft, thus providing the basis for making water control measures. Identification of Land Collapse Areas. Land collapse, which happens after working-out of the underground workings, is a main potential trouble of large and old mines. By using colour infrared aerial photographs, the collapse areas were determined. The fixed, semi-fixed and developing collapse area could be distinguished. By using muilti-temporal remote sensing techniques the developing direction, velocity of the collapse area and influenced areas have been determined, providing the basis for residents moving and making up for economic loss. Application for Investigation of Geological Hazard Dun-suan Coal Mine is located in the montain area. By using airborne images, the investigation of geological hazard was carried out in 255km2 areas with total 56 sites of collapse and 154 sites of landslide were determined, through interpretation both ground and underground data, 90% of the hazards was believed to be related to the coal production activity. We have conducted a dynamic analysis of the developing tendency of landslide in the last 20 years by using multi-temporal images. As a results. The collapse and landslide of coal mine mostly happened ten years after working -out of shaft. we also found out that if waste rocks were set in proper places, it would influence the safety of shaft. By removing the waste rock, the landslip will gradually become stable. Investigation of Environmental Pollution of Coal Mine The coal mine is the main pollution source, including air, ground , water pollution. The investigation of environmental pollution caused by coal mines was carried out by using airborne colour infrared photography and thermal infrared scanning image. Compared with the other ways, the methods used in Dun-zuan Coal Mine, reduce the working time by half and costs by 80%. The above result shows remote sensing is the most effective technical means for the study of pollution source, area and extents. References Guan Haiyan, the research of coal bed thermal IR radiation. Proceedings of the Seminar on Remote Sensing for Geological Applicaitons, 1984, pp. 535-547. Yang Qi and Han Dexin ed)., Coal Geology, Vol.1, Coal Publishing House (in Chinese) , 1984 pp. 209-248. Zhu Liangpu, Cheng Jicheng, Pan Deyang and Fan Xinqi., A Course of Geologcal Interpretation of Remote Sensing Image, Geological Publishing House (In Chinese), 1981, pp. 324-340. Guan Haiyan, Acta Geological Sinica (in Elglish). VOl. 2 (1989), No 3, pp 253-269.