Landscape Ecological Risk Assessment And Driving Force Analysis Of The Weihe River Basin

Since the 1990s,with the rapid development of China’s economy and the rapid increase of the population,the region ecological environment has been strongly disturbed by human factors,and the irrational use of land resources also seriously affected the stability of region ecology.Landscape ecological risk assessment(LERA)is based on land use landscape,and the assessment model was constructed by selecting and calculating the appropriate landscape index in land use time series.The landscape ecological risk change can reveal the pattern of landscape ecological risk and the influence of natural factors and human activities in the region.Therefore,the research on LERA is very important for the rational allocation of land resources,ecological environmental protection and the promotion of sustainable utilization of resources in the region.The paper analyzed the spatial-temporal changes of land use types in Weihe River Basin from 1990 to 2018,and using landscape indexes to construct LERA model.The spatial-temporal changes of landscape ecological risks have been analyzed.Combined with the geographical weighted regression model and geographical detectors,the driving factors of landscape ecological risk occurrence in the Weihe River Basin,the intensity of the driving factors on the spatial distribution of landscape ecological risks,and the interaction between driving factors on the occurrence of landscape ecological risks were studied.The main conclusions are as follows:(1)Based on land use data form Data Center for Resources and Environmental Sciences.Chinese Academy of Sciences,the spatial and temporal changes of land use in the Weihe River Basin were quantitatively analyzed from the aspects of quantity,structure,dynamic degree and transfer direction of land use types.The results showed that during the whole study period,cultivated land and grassland were the main land use types in the Weihe River Basin,and the area of cultivated land and grassland accounted for more than 75%of the total area.From the perspective of the spatial-temporal dynamics of land use change in the Weihe River Basin,the comprehensive dynamics of the Weihe River Basin showed an ’N-type’ development trend,in which the maximum comprehensive dynamic degree from 2015 to 2018 was 4.80%.The change of comprehensive land use types in the Weihe River Basin during this period was the most significant.From the perspective of the number and direction of land use type transfer,the transformation mode of land use class in the Weihe River Basin are mainly the mutual transformation between cultivated land and grassland,the transfer of cultivated land and the transfer of construction land.(2)Landscape fragmentation,landscape separation,landscape advantage and landscape vulnerability in landscape ecology were selected to construct landscape ecological risk evaluation model from 1990 to 2018 for Weihe River Basin.The spatial-temporal autocorrelation and spatial heterogeneity were explored by spatial autocorrelation methods.The results showed that from 1990 to 2018,the area of lower-risk,medium-risk and higher-risk areas in the Weihe River Basin were increased,and the area of high-risk areas was decreased.The areas of lower-risk areas,medium-risk areas and higher-risk areas increased by 2.94%,4.97%and 3.54%respectively,and the area of high-risk areas decreased by 11.24%.These indicated that the landscape ecological risk of the Weihe River Basin showed a decreasing trend during the whole period.It also showed that the landscape ecological risk in the Weihe River Basin is developing in a good direction.The spatial autocorrelation analysis showed that the landscape ecological risks of the Weihe River Basin had a significant positive correlation in space from 1990 to 2018,and the spatial distribution showed the forms of "high-high" aggregation and"low-low" aggregation.(3)The factors for the occurrence of ecological risks in the Weihe River Basin were selected from the aspects of natural factors and human factors,and then interactive detectors were used to interactively detect the dominant factors.The intensity of the driving factors and the interaction between driving factors were studied by geographical weighted regression model and geographical detectors.The results showed that the significant driving factors were DEM,slope,precipitation,annual average temperature,relative humidity,population density and human interference.The intensity and spatial differences of the driving factors on the landscape ecological risk of the Weihe River Basin are different,and the intensity of human interference was most important.From the perspective of the interaction between the driving factors,the explanatory power of the occurrence of landscape ecological risk in the Weihe River Basin after the interaction of slope and human interference has reached more than 60%,and the intensity of the interaction of the two driving factors were greater than single driving factor,which indicated that the occurrence of landscape ecological risk in the Weihe River Basin was not only the result of a single driving factor,but also the result of the interaction between the driving factors.