| A good ecological environment is the environment and material basis for the development of human civilization.With the rapid development of the national economy and the vigorous promotion of urbanization,the state has put forward the strategy of coordinated development of urban agglomerations in a timely manner,but this will lead to a sharp reduction in ecological land around the city,excessive consumption of natural resources,aggravation of environmental pollution,degradation of ecosystem functions,causing great pressure on the ecological environment,and at the same time restricting the high-quality development path of the city.Taiyuan urban agglomeration is one of the 14 urban agglomerations that the state focuses on construction,and plays an important role in the development of the Yellow River Middle Reaches Economic Zone,which is of great significance for narrowing the gap between the central and western regions and coordinating regional development.Based on the MODIS data of 2002,2007,2012,2017 and 2021,this paper extracts indicators such as greenness(NDVI),humidity(WET),heat(LST),and dryness(NDBSI)to construct a remote sensing ecological index model(RSEI)of Taiyuan urban agglomeration,studies the temporal and spatial evolution characteristics of ecological environment quality,and reveals the driving factors of ecological environment change.By constructing the Night Light Index(CNLI),the temporal and spatial changes of the urbanization level of Taiyuan urban agglomeration are analyzed,and the coupling coordination degree between ecological environment quality and urbanization level is studied by using the coupling coordination model,in order to provide a theoretical basis for the restoration and coordinated development of ecological environment in Taiyuan urban agglomeration,and the main research results are as follows:(1)The results of principal component analysis showed that the contribution rate of the first principal component was more than 70% in the five study years,indicating that RSEI better concentrated most of the information of greenness,humidity,heat and dryness.Multiple linear regression and Pearson correlation coefficient showed that RSEI had a good correlation with various indexes,among which greenness and humidity promoted the ecological environment,and heat and dryness hindered the ecological environment.Among the four indicators,greenness and dryness have a greater impact on the ecological environment.It is reasonable to use RSEI to characterize the quality of the ecological environment in the study area.(2)The overall ecological environment quality of the Taiyuan urban agglomeration showed an upward trend,but it was still at a low level.The mean RSEI values were 0.433,0.441,0.421,0.460 and 0.488 in 2002,2007,2012,2017 and 2021,respectively.Except for the small shop area,the average change law of RSEI is roughly the same as that of other counties.A large proportion of areas with a moderate or poor ecological quality rating consistently accounted for a large proportion of the five study years,with shifts in ecological quality over time.In terms of spatial distribution,the ecological environment quality of Taiyuan urban agglomeration shows a trend of "high in the west and low in the east",with obvious spatial autocorrelation,most of which belong to high-high aggregation and low-low aggregation.Between 2002 and 2021.The ecological improvement areas were mainly distributed in Lan County,Jingle County and the northwest of Loufan County in the north of the study area,and the degraded areas were mainly distributed in the south of Xiaodian District,Qingxu County and Yuci District.(3)The night light index(CNLI)was used to characterize the urbanization level of Taiyuan’s urban agglomeration.From 2002 to 2021,the overall urbanization level in the study area increased,and the degree of change varied in different districts and counties,among which the CNLI value in Xiaodian District increased the most,reaching 0.907 in 2021,and the urbanization level was the highest.In terms of spatial distribution,the pattern of "high in the east,low in the west" and "high in the south and low in the north" is presented,and the development of urbanization level in the study area is uneven.From 2002 to 2021,the coupling and coordination degree(D value)of ecological environment and urbanization level increased,and the D value reached 0.571 in 2021,and the whole Taiyuan urban agglomeration was in a state of close coordination.At the district and county scale,the number of districts and counties that have achieved run-in development and coordinated development has increased significantly.The spatial distribution is similar to the distribution of CNLI values,the coupling coordination level in the northern part of the study area is low,the urbanization level is low,the urbanization development lags behind the ecological construction,and the southern part is relatively balanced. |
