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EXPLORATION ON METHOD OF AUTO-CLASSIFICATION FOR MAIN GROUND OBJECTS OF THREE GORGES RESERVOIR AREA

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Chinese Geographical Science 2005年第2期15卷 157-161页

作者： ZHANGBao-lei SONGMeng-qiang ZHOUWan-cun chengduinstituteofmountainhazardsandenvironment ChineseAcademyofSciences＆MinistryofWaterConservancyChengdu610041P.R.China／／GraduateSchoolofChineseAcademyofSciencesBeijing100039P.R.China chengduinstituteofmountainhazardsandenvironment ChineseAcademyofSciences＆MinistryofWaterConservancyChengdu610041P.R.China

Taking TM images, SPOT photos and DEM images as the basic information, this paper had not only put forward a kind of manual controlled computer-automatic extraction method, but also completed the task of extracting the main types of ground objects in the Three Gorges Reservoir area under relatively high accuracy, after finishing such preprocessing tasks as correcting the topographical spectrum and synthesizing the data. Taking the specialized image analysis software-eCognition as the platform, the research achieved the goal of classifying through choosing samples, picking out the best wave bands, and producing the identifying functions. At the same time the extraction process partly dispelled the influence of such phenomena as the same thing with different spectrums, different things with the same spectrum, border transitions, etc. The research did certain exploration in the aspect of technological route and method of using automatic extraction of the remote sensing image to obtain the information of land cover for the regions whose ground objects have complicated spectrums.

关键词： automatic extraction ground object identifying functions Three GorgesReservoir area

Zonal Distribution of the Erosion-Landslide and Soil Micromorphological Features in Purple Hilly Region

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Journal of Mountain Science 2005年第1期2卷 42-49页

作者： HEYurong LIAOChaolin XUPei ZHANGBaohua chengduinstituteofmountainhazardsandenvironment ChineseAcademyofSciencesChengdu610041China

In the purple hilly region, erosions and landslides are all serious, and it is of great scientific value and practical significance to study their formation mechanism and distribution features there. In this paper, soil micromorphological methods and techniques were used to study the erosion zonal distribution in the region. The results indicated: (1) According to erosion process, the spacial distribution zones of the erosions and landslides in the purple hilly region with different solums were divided into scouring erosion zone, transport-diffusion zone, rocks and soil turbulence zone and sediment-bury zone; (2) The soil micromorphologic taxonomic feature identifying different erosion-landslide zone were found by studying the soil micromorphology of erosive zone in purple hilly region; (3) As for the erosion–landslide formation in the region, besides the external factors, the internal factors were found more important and favorable for landslide formation through the studies on the micormorphological features of slide soil.

关键词： Purple hilly region erosion-landslide zonal distribution soil micromorphology

A study on responses of soil erosion and sediment yield to closing cultivation on sloping land in a small catchment using (137)Cs technique in the Rolling Loess Plateau, China

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Chinese Science Bulletin 2003年第19期48卷 2093-2100页

作者： FENGMingy D.E.Walling ZHANGXinbao WENAnbang chengduinstituteofmountainhazardsandenvironment ChineseAcademyofSciences(CAS)Chengdu610041China DepartmentofGeographyandArchaeology ExeterUniversityEeterEX44RJUK

Abstract By comparison of volumes and 137Cs contents of the deposited sediments before and after 1993, changes of specific sediment yields and relative sediment contributions from the gully area and from the inter gully area after closing cultivation on the later area on a small catchment of Zhaojia Gully, in the Rolling Loess Plateau, are analyzed in this paper. Closing cultivation in a large scale has not resulted in decrease but increase of specific sediment yield of the catchment, in sharp decrease of the sediment yield and the relative sediment contribution of the inter-gully area, and in increase of the sediment yield and the contribution of the gully area, for a short term. The mean specific sediment yield of 29650 t km-2 a-1 of 1994—1996 in the catchment was 2.2 times the average value of 13413 t km-2 a-1 for a long term. The specific sediment yield of the inter-gully area decreased from the 14335 t km-2 a-1 in 1994 to 7034 t km-2 a-1 in 1995 and 3517 t km-2 a-1 in 1996, while the yield of the gully area varied between 44944 and 62136 t km-2 a-1 during the period of 1994—1996 which was much greater than the value of 21118 t km-2 a-1 before 1993. The relative sediment contribution from the inter-gully area decreased from 23% in 1994 to 15% in 1995 and 6% in 1996, while the contribution from the gully area increased from 77% in 1994 to 85% in 1995 and 94% in 1996. It is suggested that compacting of ploughed soils resulted in increasing of the erosion resistance but in decreasing of the precipitation infiltration, therefore, the soil erosion reduced but the runoff amount increased on the inter-gully area. Increase of delivering runoff from the inter-gully area to the gully area should result in activeness of gully erosion and mass movements, consequently, in increase of the total sediment yield from the catchment.

关键词：沉积量土壤侵蚀倾斜地带汇水盆地 137Cs 起伏黄土高地沉积作用

Numerical analysis on intermittent flow in a longitudinal section of Bingham fluid along a slope

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Chinese Science Bulletin 2003年第17期48卷 1870-1876页

作者： LIUDayou XUShengli ZHANGShucheng YUBing DUANXinpin YUEPengtao InstituteofMechanics ChineseAcademyofSciencesBeijing100080China DepartmentofMechanicsandMechanicalEngineering UniversityofScienceandTechnologyofChinaHefei230026China chengduinstituteofmountainhazardsandenvironment ChineseAcademyofSciencesChengdu61004lChina

The transition process of intermittent flow in a longitudinal section of Bingham fluid from initial distribu-tion to fully developed state was numerically investigated in this paper. The influences of slope ,J dimensionless runoff Q* and viscosity m*0on the dimensionless surge speed U* were also presented in a wide range of parameters. By one typical example, the intermittent flow possessed wave char-acteristics and showed a supercritical flow conformation for a fully developed flow. The distributions of gravity and bed drag along the flow path and the velocity distribution of flow field were also analyzed.

关键词：泥石流间歇流动宾汉流体纵断面波动速度

210Pb(ex) depth distribution in soil and calibration models for assessment of soil erosion rates from 210Pb(ex) measurements

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Chinese Science Bulletin 2003年第8期48卷 813-818页

作者： ZHANGXinbao D.E.Walling FENGMingyi WENAnbang StateKeyLaboratoryofLoessandQuaternaryGeology InstituteofEarthEnvironmentCASXi'an710075China DepartmentofGeographyandArchaeology ExeterUniversityExeterUKEX44RJ chengduinstituteofmountainhazardsandenvironment ChineseAcademyofSciences(CAS)Chengdu610041China

Three soil cores collected from China and UK show the 210Pbex and 137Cs depth distribution on uncultivated and cultivated land. Depth distributions of the two nuclides are very similar. Those nuclide concentrations are higher in the top horizon and decrease exponentially with depth on uncultivated land while the concentrations are almost uni-form throughout the plough layer as a result of mixing asso-ciated with cultivation on cultivated land. 210Pbex reference inventory in the Loess Plateau is 573 mBq·cm-2, a little higher than 520.0 mBq·cm-2 in UK. Distribution of artificial fallout 137Cs, produced during the nuclear testing period of the late 1950s and 1960s, is in an unsteady state. In contrast, distribution of natural fallout 210Pbex is in a steady state un-der constant conditions of land environment and erosion processes for a long term, e.g. >100 years. Therefore, mass balances of 137Cs and 210Pbex in soil are different. According to its processes of continues deposition from the atmosphere, nature decay and losses with soil losses, 210Pbex steady state mass balance models for cultivated land as well as for uncul-tivated land are developed to estimate soil erosion rates in this paper. Besides, the proportion of freshly deposited 210Pbex fallout removed by erosion on cultivated land can also be calculated from 210Pbex depth distribution at a reference site of uneroded permanent grass land.

关键词： ^210Pbex 铅土壤侵蚀铯铀

Approach to Mountain Hazards in Tibet, China

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Journal of Mountain Science 2004年第2期1卷 143-154页

作者： MADongtao TUJianjun CUIPeng LURuren chengduinstituteofmountainhazardsandenvironment ChineseAcademyofSciences＆MinistryofWaterConservancyChengdu610041SiehuanChina SouthwestNormalUniversity Chongqing400715China

Tibet is located at the southwest boundary of China. It is the main body of the Qinghai-Tibet Plateau, the highest and the youngest plateau in the world. Owing to complicated geology, Neo-tectonic movements, geomorphology, climate and plateau environment, various mountain hazards, such as debris flow, flash flood, landslide, collapse, snow avalanche and snow drifts, are widely distributed along the Jinsha River (the upper reaches of the Yangtze River), the Nu River and the Lancang River in the east, and the Yarlungzangbo River, the Pumqu River and the Poiqu River in the south and southeast of Tibet. The distribution area of mountain hazards in Tibet is about 589,000 km2, 49.3% of its total territory. In comparison to other mountain regions in China, mountain hazards in Tibet break out unexpectedly with tremendously large scale and endanger the traffic lines, cities and towns, farmland, grassland, mountain environment, and make more dangers to the neighboring countries, such as Nepal, India, Myanmar and Bhutan. To mitigate mountain hazards, some suggestions are proposed in this paper, such as strengthening scientific research, enhancing joint studies, hazards mitigation planning, hazards warning and forecasting, controlling the most disastrous hazards and forbidding unreasonable human exploring activities in mountain areas.

关键词： Tibet mountain hazard formation cause danger mitigation countermeasure