Numerical Environment Modeling Of Jinqu Basin Based On The Geological Factors

The formation and the evolution of the earth's surface environment are based on the basic geological structural pattern.The geological structures in the deep earth,lithology of the land surface,and the soil types will restrict and influence the development of the environment. However,for the global or regional environment problems,few studies considered the influence of the geological factors.In this paper,focused on the topics of land use/cover image classification,relation analysis between the basic geological factors and the environment, integrated environment evaluation index(IEEI) creation,environment change driving force comparison among different influencing factors,numerical environment modeling,and so on, taken Jinqu basin,located in Zhejiang Province of China,as the case study area,and used Landsat TM/ETM+ images,basic geological data(fault,lithology,and soil),topographical data (DEM and slope),meteorological data(rainfall,evaporation and temperature),and social-economical data(population and GDP),a numerical model for integrated environment analysis was introduced.At first,the NDVI(Normalized Difference Vegetation Index),NDWI (Normalized Difference Water Index),NDBI(Normalized Difference Build-up Index) and tasseled cap transformation wetness was extracted,according to the spectral characteristics of each multi-spectral band of the TM/ETM+ images;the land surface temperature(LST) was calculated from the thermal infrared band of the TM/ETM+ images;and the land use/cover types was classified by using the integrated classifier that designed by the author.Secondly,the relation between the faults and the environment indicating factors(NDVI,LST,and soil moisture) was analyzed,and the influencing mechanism of the geological factors to the environment change was summarized.Thirdly,an integrated environment evaluation index (IEEI) that can be used to evaluate the conditions of the environment was obtained,by using the factor analysis;the environment conditions of the study area on 1988 and 2000 were quantitatively evaluated.Fourthly,the change of the environment influencing factors,including basic geological factors,topographical factors,meteorological factors,and social-economical factors were quantitatively analyzed,and their driving force to the environment change was compared.Finally,a numerical model between the environment influencing factors and the IEEI was created,and the trend of the environment change in the near future was analyzed.The main evolves and results are like follows:1) An integrated classification method for Landsat TM/ETM+ images that combined decision tree with maximum likelihood classifier,slope,NDWI,NDVI and NDBI was introduced,according to the distribution characteristics of the topography,geomorphology and land surface objects.In the study,the integrated classifier taken the decision tree as basic classification algorithm,reduced the phenomena of objects with similar spectrum between the vegetations of living on forest and agricultural land,by using the slope data;extracted the water,agricultural land,and mountainous bare land,with the ancillary data of NDVI,NDWI and NDBI;and distinguished urban and bare land on plain,by using the maximum likelihood classifier.2) The Subsection Mean Method(SMM) based on the mean statistic algorithm was introduced,in allusion to the land surface temperature field analysis of the fault system.It chooses a given area on both sides of the fault as the analysis area,partitions the area into numbers of parts according as the distance to the fault,calculates the mean land surface temperature(LST) and the mean distance of each subsection,and plots the correlation curve of the mean LST and the mean distance.Then obtain the rough influencing width of the fault to the land surface thermal field on the correlation curve.The results indicated that,the nearer to the faults of the study area,the higher is the LST.And the rough influencing width of Jianshan-Shaoxing fault,Qiuchan-Xiaoshan fault,Changshan-Lizhu fault,Chun'an-Wenzhou fault,Songyang-Pingyang fault,and Quzhou-Tiantai fault is 16,3,5,11,4,and 13 kilometers, respectively.3) A thermal infrared anomaly characterization method based on scale analysis was introduced,according to the characteristics of the object,including thermal anomaly represented by pixel or pixel congregations on the thermal infrared remote sensing image,that it has special geometric scale.It effectively reduced the background interference information, enlarged the thermal anomalies from the subsurface,and objectively characterized the planar distribution shapes and characteristics of the thermal anomalies around the faults of the study area:The anomalies were linearly distributing along both sides of Jiangshan-Shaoxing fault and Changshan-Lizhu fault,and were concentrating upon the intersectional area of Chun'an-Wenzhou fault with Changshan-Lizhu fault and Quzhou-Tiantai fault.4) The influencing mechanism of the geological factors to the environment was analyzed and summarized.In the study area,the thermal flow transmitting from the subsurface,along the faults,result in land surface thermal anomaly,and influence the land surface thermal environment.The weathering pattern of the lithology influences soil types and their features, complexity and difficulty of the land surface ecological environment,and hydrological features. So the lithology greatly influences the environment on the basic geological conditions. Moreover,due to the structures and components of the mother rocks,the soils with different cavity,thickness,and weather feature result in different moisture and temperature conditions for vegetation living.5) Three thematic data of NDVI,LST and soil moisture that can reflect the natural ecological environment,land surface thermal environment,and agricultural environment was analyzed,and the IEEI that can be used to evaluate the integrated environment was obtained, by using the factor analysis.The comparison result,between the two indices of 1988 and 2000, indicated that the environment of the study area suffered great change.Holistically speaking, the integrated environment was getting better.But,the relatively worse area was transferring from the mountainous area to the plain.6) The driving force of the basic geological factors,topographical factors,meteorological factors,and social-economical factors to the environment was compared,and a numerical relation model between the environment influencing factors and the IEEI was created.The results indicated that,during the study period,the primary reason of influencing the environment is the climate change.The second reason is the geological and topographical evolution.And the third reason is the social-economical development.In a short time period, the basic geological and geographical environment is relatively stable,so the environment will be easily influenced by the factors of soil erosion,evaporation,rainfall,temperature, population and GDP.