| Earthquakes,especially strong earthquakes and their secondary geological disasters,cause a large number of casualties and property losses in the short term,while changing the regional landscape pattern,leaving a large number of hidden dangers,changing the inner process or characteristics of near-surface system,affect the regional carrying capacity and resilience for a long time,and change the regional eco-geological environment security status at the same time.Ten counties and cities seriously affected by “Wenchuan Earthquake” were selected as the study area to carry out the ecological geological survey from the perspective of the safe evolution of the ecological geological environment,combined with data mining methods such as literature review,field sampling and remote sensing inversion using GIS to analyze and monitor the spatio-temporal distribution of regional ecological environment,human activities and geological disasters,and to construct the evaluation index system of the security spatio-temporal change of eco-geological environment in the areas prone to geological disasters,to evaluate the safety state of eco-geological environment in different periods,to analyze the evolution mechanism and development trend of eco-geological environment safety in the areas prone to geological disasters,and to explore the ways of restoration and treatment of eco-geological environment,discussion on the protection mode of eco-geological environment security.To promote the study of eco-geological environment in China and improve the theoretical system of eco-geology,and provide a basis for disaster prevention and reduction in the areas prone to geological disasters.The main innovative results of this study are as follows:(1)Through the thought of population,economy and land use,the spatial and temporal changes of human activity subsystem from 2000 to 2017 were comprehensively evaluated and analyzed.The results show that the social economy in the study area is obviously affected by geological disasters,and the land use and landscape pattern change obviously with the deepening of human disturbance.The distribution of population in the study area is uneven,and there is a big difference in population density.The per capita GDP of the counties and cities decreased significantly affected by the Wenchuan earthquake in 2008.During the year of 2000 to 2015 the land use change in the study area was obvious,and there was mutual transfer among different land types,especially the change of construction land and bare land.In the year of 2000 and 2005,the land use landscape pattern in the study area was uniform,the fragmentation and separation of the landscape pattern increased from 2010,the connectivity decreased,the landscape pattern distribution was worst in 2015,and the security of ecological geological environment was challenged.(2)The results of emergency investigation of geological hazards indicate that the secondary geological hazards induced by earthquake are distributed in a belt and a line along the Longmenshan Fault and river system at 2981 potential geological hazard points.According to the analysis of the information of hidden danger points of geological hazards,the sensitivity of geological hazards decreases gradually with the distance from the fault,and the area with the elevation of 800 ? 1800 m and the slope of 8 ? 24 is most sensitive to the geological hazards triggered by earthquakes.Based on the information model to evaluate the stability of the geological environment in the study area,the results show that the low stability of the geological environment is a prominent feature of the geological environment in the study area,the low and the lower stability area of the geological environment account for 65.1502% of the total area,and the spatial distribution pattern of the geological environment stability along the yingxiu-beichuan fault is middle high on both sides and high in the south and low in the north.(3)Based on multi-source remote sensing image data and meteorological statistical data,the key parameters of eco-environment subsystem were inversed and analyzed under the guidance of quantitative remote sensing method.The results showed that the vegetation coverage in the study area had obvious spatial differentiation,the average annual vegetation coverage from 2000 to 2017 showed a downward trend,the downward trend was not obvious about 0.17% / A,the degradation area of vegetation coverage in the study period was slightly higher than the improvement area,on the whole,the change of vegetation coverage is most closely related to rainfall in the study area.From 2000 to 2017,the rainfall in the study area is greater than the evapotranspiration,which can well conserve water resources,and the level of water conservation has been continuously enhanced,the soil erosion ability in the southeast mountainous area of the study area is strong,and the change is relatively obvious;the carbon-fixing oxygen-releasing capacity as a whole fluctuates greatly,but the linear trend is not obvious,and the average carbon-fixing oxygen-releasing capacity is high;The biodiversity maintenance index in the western region is generally lower than that in the southeast region.(3)Based on the eco-geological environment investigation and dynamic monitoring,combined with the data of social economy,geological environment and ecological environment in the study area,by selecting 28 important eco-geological safety indicators,such as population density,water conservation,soil conservation,and surface undulation,the DPSIR model was developed and improved,and the eco-geological environment safety evaluation system of the study area was established.The indexes of eco-geological safety were weighted by the method of subjective weight(AHP)and objective weight(Entropy),and the safety condition of eco-geological environment in different periods was quantitatively evaluated.(5)The results of evaluation tell us that the overall eco-geo-environmental safety index in the study area is on the low side and the low value areas are on the high side,and the distribution of eco-geo-environmental safety index has obvious positive spatial autocorrelation,the low value areas of eco-security index were concentrated in the northern part of the study area,the high value areas were mainly concentrated in the western high-altitude mountains and the eastern plain,and some nature reserves in the central part of the study area.The results of the study on the spatio-temporal change of the eco-geological environment security show that the analysis of the regional eco-security change shows that the eco-security index of the study area has decreased significantly from 2000 to 2015,and the eco-security index has decreased significantly in the last five years,the region with lower ecological environment dominates the development direction of ecological security in the whole research area.The highest ecological security index in County area is Wenchuan County,and the lowest ecological security index is Qingchuan County,since the beginning of the study period,the county ecological security index has continued to decline,and the ecological security risk is extremely high.In conclusion,from the perspective of eco-geological Environment Security,this study analyzes the spatio-temporal variation characteristics of the complex system of "Human-Geology-Ecology" under the constraints of geological disasters,experiment a technical method of "Investigation on basic data of eco-geological environment-Dynamic information monitoring and inversion-Safety condition evaluation-Spatio-temporal analysis",and established a relatively perfect safety evaluation model of eco-geological environment in geological disasters striken area,which provides a new idea and method for eco-geological survey,Remote Sensing Information Inversion,dynamic monitoring and evaluation,it provides a theoretical basis for the construction of ecological security pattern in the geological disaster-prone areas and is of great significance for the construction of regional ecological civilization and the study of sustainable development. |
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