| Other Abstract | Urban resilience is a hot topic in many fields such as urban planning and governance, disaster prevention, and sustainable development. It has important theoretical and practical significance for ensuring urban safety, optimizing spatial layout, and promoting the coordinated development of social ecosystems. Lanzhou is a typical city which natural and human development conditions are limited and urban security issues are prominent in the ecologically fragile region of the Northwest China. Based on the perspective of "Size-Density-Morphology"resilience framework, via GIS and RS platform, using Lanzhou statistical data, land use interpretation data, related planning data, etc. as data sources, along with landscape ecology theory and ecological infrastructure analysis tools, the paper illustrate the spatial and temporal features of urban resilience of Lanzhou during 1990- 2017, Results showed that:
(1)70.71% of the area in Lanzhou is within the lowest standard EI (Ecological Infrastructure), the second is the middle standard EI, accounting for 27.72%, and the highest standard EI occupies the least areaDuring the study period, the size resilience generally showed a downward trend, of which the decline was rapid from 1990 to 2005 and slowed down after 2005in this period, the urbanization rate of land in the five districts and three counties continued to increase, the spillover effect of urban expansion was obvious, and urban development was facing strong scale security constraints.
(2)From 1990 to 2010, the density resilience index of Lanzhou continued to decline and it has rebounded since 2010, but the overall trend is still decliningAmong the land for ecological footprint, the highest proportion and fastest rising are fossil energy land. This is because economic development is at the cost of high energy consumption and is also inseparable from the industrial structure.
(3)The variation in morphological resilience is small and generally stable, which indicating that the overall morphological unit of Lanzhou and the districts and counties did not change much during the study period. Only the morphological adjustment of local units existed and the landscape pattern was relatively endurance.
(4)The three levels of resilience have significant differences among districts (counties). The size and density resilience of the "five districts"(Chengguan District, Qilihe District, Anning District, Xigu District, and Honggu District) are much lower than those of the "three counties"(Yongdeng County, Gaolan County, Yuzhong County), which are extremely imbalanced in space. Only Yongdeng County has a morphological resilience that exceeds the average level of Lanzhou City and has the best form, while the coupling between the source-sinklandscapes in other districts and counties is low.
(5)During the study period, the features of Lanzhou's resilience combination are relatively stable, and no combination conversion occurred. Yongdeng County has the best combination, and all three types of resilience are at a high level, indicating that the county has the highest level of security. Secondly, in Gaolan County and Yuzhong County, the safety level of "two highs and one low"(high size resilience, high density resilience, low morphological resilience). While the "three lows"(low size resilience, low density resilience, and low morphological resilience) in "Five Districts"need urgent attention.
(6)The differences between the size resilience and density resilience of each district and county and the average level of Lanzhou are gradually narrowing, indicating that the overall level of resilience develops to an equilibrium state over time, while the gap between morphological resilience and the average level of Lanzhou has remained basically unchanged.
(7)This study proposes corresponding improvement strategies based on the assessment results of urban resilience in Lanzhou. First of all, avoid excessive concentration of construction to form landscape pressure, plan land use based on ecological infrastructure, and control the disorderly spread of cities. Secondly, Optimize industrial structure, increase intensive use of resources and improve population quality. Last but not least, optimize the form of urban space and increase green patches.
In order to improve urban resilience, it is necessary to optimize urban layout and improve morphological characteristics. The case study also shows the "size-density-morphology"analysis framework has a good reliability in understanding urban resilience.
Urban resilience is a hot topic in many fields such as urban planning and governance, disaster prevention, and sustainable development. It has important theoretical and practical significance for ensuring urban safety, optimizing spatial layout, and promoting the coordinated development of social ecosystems. Lanzhou is a typical city which natural and human development conditions are limited and urban security issues are prominent in the ecologically fragile region of the Northwest China. Based on the perspective of "Size-Density-Morphology"resilience framework, via GIS and RS platform, using Lanzhou statistical data, land use interpretation data, related planning data, etc. as data sources, along with landscape ecology theory and ecological infrastructure analysis tools, the paper illustrate the spatial and temporal features of urban resilience of Lanzhou during 1990- 2017, Results showed that:
(1)70.71% of the area in Lanzhou is within the lowest standard EI (Ecological Infrastructure), the second is the middle standard EI, accounting for 27.72%, and the highest standard EI occupies the least areaDuring the study period, the size resilience generally showed a downward trend, of which the decline was rapid from 1990 to 2005 and slowed down after 2005in this period, the urbanization rate of land in the five districts and three counties continued to increase, the spillover effect of urban expansion was obvious, and urban development was facing strong scale security constraints.
(2)From 1990 to 2010, the density resilience index of Lanzhou continued to decline and it has rebounded since 2010, but the overall trend is still decliningAmong the land for ecological footprint, the highest proportion and fastest rising are fossil energy land. This is because economic development is at the cost of high energy consumption and is also inseparable from the industrial structure.
(3)The variation in morphological resilience is small and generally stable, which indicating that the overall morphological unit of Lanzhou and the districts and counties did not change much during the study period. Only the morphological adjustment of local units existed and the landscape pattern was relatively endurance.
(4)The three levels of resilience have significant differences among districts (counties). The size and density resilience of the "five districts"(Chengguan District, Qilihe District, Anning District, Xigu District, and Honggu District) are much lower than those of the "three counties"(Yongdeng County, Gaolan County, Yuzhong County), which are extremely imbalanced in space. Only Yongdeng County has a morphological resilience that exceeds the average level of Lanzhou City and has the best form, while the coupling between the source-sinklandscapes in other districts and counties is low.
(5)During the study period, the features of Lanzhou's resilience combination are relatively stable, and no combination conversion occurred. Yongdeng County has the best combination, and all three types of resilience are at a high level, indicating that the county has the highest level of security. Secondly, in Gaolan County and Yuzhong County, the safety level of "two highs and one low"(high size resilience, high density resilience, low morphological resilience). While the "three lows"(low size resilience, low density resilience, and low morphological resilience) in "Five Districts"need urgent attention.
(6)The differences between the size resilience and density resilience of each district and county and the average level of Lanzhou are gradually narrowing, indicating that the overall level of resilience develops to an equilibrium state over time, while the gap between morphological resilience and the average level of Lanzhou has remained basically unchanged.
(7)This study proposes corresponding improvement strategies based on the assessment results of urban resilience in Lanzhou. First of all, avoid excessive concentration of construction to form landscape pressure, plan land use based on ecological infrastructure, and control the disorderly spread of cities. Secondly, Optimize industrial structure, increase intensive use of resources and improve population quality. Last but not least, optimize the form of urban space and increase green patches.
In order to improve urban resilience, it is necessary to optimize urban layout and improve morphological characteristics. The case study also shows the "size-density-morphology"analysis framework has a good reliability in understanding urban resilience. |
