| The geological environment in most areas of Yunnan is fragile,which is one of the provinces with thelargest investment in geological disaster prevention and control.Shangri-La is located in the ecological fragile area of the canyon area of northwest Yunnan Plateau,and is also a modern surface activity experimental area and a national key ecological reserve.The purpose of this study is to explore the vulnerability and risk ofgeological hazards in this area from the perspective of environmental ecology and geology,and to provide data support and suggestions for land and space planning and geological disaster prevention and control.Based on RS and GIS technology,combined with the basic data of field investigation,the development and distribution characteristics of geological hazards are quantitatively revealed,and the static control factors of geologicalhazards were preliminarily analyzed.This study analyzed the LUCC(land use/cover change)in four periods,and combines CA-Mar model to fit LUCC under the current situation and the LUCC trend under the future scenario.The spatial distribution of land surface temperature and humidity at county scale was discussed by using remote sensing data,and the distribution characteristics of air temperature and precipitation in the past50 years(1961-2010)and the next 30 years(2031-2060)were analyzed,the dynamic factors related togeological hazards were obtained.Finally,the current situation and the vulnerability and danger of geological hazards were evaluated by using the model,and the prevention and control suggestions for geological hazards were preliminarily explored:(1)Through remote sensing interpretation,combined with ground survey data,416 landslides,179collapses and 262 debris flow gullies were interpreted,and combining with the existing records,this study analyzed the time and spatial distribution characteristics,scale,characteristics,dangerous situation andinducing factors of geological disasters;The results showed that the spatial distribution of geological hazards is characterized by regional accumulation and distribution along faults and clastic rocks.The density of hazard points is high in the south and northwest,low in the east and middle,along river valleys and structural belts.(2)The radar ratio index method was used to rapidly extract landslide and monitor disaster.Compared with the survey results,the overall accuracy was better,which met the requirement of rapid extractionaccuracy;the method had good effect in the application of geological disaster extraction and monitoring for sentinel-1 SAR,and it should have a broad prospect;the rapid extraction method of geological hazardinformation proposed in this study can provide information support for emergency relief and monitoring.(3)Obtaining indirect information related to basic data through various technical means,which can be called model evaluation factor.(1)The land surface temperature(LST)data were obtained by using the 8-day synthetic lst product of MODIS sensor,which was downloaded from the NASA website.The annual mean lstand its spatial distribution in the study area were obtained by Data pre-processing and spatial interpolation method;(2)Using the negative correlation between the normalized vegetation index and the surfacetemperature,combined with the correlation equation to calculate the soil moisture in the study area,the results showed that the climate conditions in Shangri La are generally relatively dry,in which the distribution range of the humid area accounts for about 6%,the normal area accounts for 13%,the micro and dry area accounts for60%,and the heavy drought area accounts for about 12%.The difference of soil moisture was significant with different vegetation coverage.(4)In this study,the daily precipitation,daily maximum temperature,daily minimum temperature and daily mean temperature of the Shangri-La City in Yunnan Province from 1961 to 2010 were calculated from0.25 to 0.25 degree,and the R software was used to run the program,the data of each grid point in the study area were extracted,and 57 extreme climate indices were calculated by using the Fortran subroutine inSTARDEX,nine temperature-related extreme indices were used to analyze the temporal and spatial variations of extreme temperature and precipitation in the past(1961-2010)and future(2031-2060)in Shangri-La City,providing meteorological data support for risk assessment of geological disasters in Shangri La.(5)Human engineering activity is an important factor affecting geological hazards.The intensity andtrend of this activity are characterized by land use change,and the change of LUCC over the past 30 years was discussed by remote sensing.The results showed that the vegetation coverage in the study area is relativelyhigh in the west,east and southwest,and low in the middle,southeast and north;the CA-Mark model was used to analyze the driving forces of land use,and the Global Kappa Coefficient of land use simulation in 2020 was0.794,the global accuracy of 85.6%shows that the simulated results are highly consistent with the measured results,and the accuracy of the CA-Markov model meets the application requirements.The model predicts the land use status in 2030 based on LUCCchange patterns of the past 30 years,the results showed that the future building land and garden land is still increasing,but the growth rate has slowed down.The average annualgrowth rate of construction land in Shangri-La City was 5.0%from 1990 to 2019,decreased to 2.0%from2019 to 2030.The average annual growth rate of the grassland over the past 30 years has been 6.8%,and will decline to 1.0%(2020-2030)in the future.Cultivated land,forest land and other land use decreased to varying degrees,the average annual reduction rate is-1.2%,-0.8%and-0.2%respectively.(6)Based on the investigation and analysis results in the past(2014),the risk and susceptibility of geological disasters in the current situation(2019)and the future(2030)were evaluated according to therelevant models.In 2019,the areas of high,medium and low-prone geological disasters in the study area were1,860.83 km~2,3008.12 km~2,4023.63 km~2,and 2367.47 km~2,respectively.The high-risk areas of geologicalhazards are mainly distributed in the southern region along the terraces of Jinsha River and its tributaries on both sides of the river valley.In 2019,the area of high,middle and low risk areas and safety areas ofgeological hazards in Shangri-la were 125.03 km~2,3500.85 km~2,6274.13km~2,1359.8km~2,respectively,the high-and medium-risk areas of geological hazards in shangri-la are mainly distributed in the valley ofDongwang River in Dongwang township and Tangmanhe River in Nixi township in the north and south.In addition,according to the relevant models,this paper forecasts the geological hazards in 2030 geological hazards susceptibility and risk grade,area and distribution areas.Based on the results of zoning thesusceptibility and risk of geological disasters,the prevention and control measures and suggestions of geological disasters based on ecological perspective are preliminarily explored.The results showed that there is still an increasing trend in the high-risk and high-risk areas of Shangri-la in the future.The static factors induced by geological disasters are basically stable,and the dynamic factors are changing,which are mainly reflected in the ecological factors,in view of the special ecological position ofShangri-la,it is necessary to prevent it from the angle of ecosystem and industrial structure adjustment in the future. |
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