| An obvious characteristic of urbanization is that the city does not penetrate the surface of water rapidly,the area and density of all kinds of buildings and structures in urban construction are increasing,and the large amount of natural surface is transformed into impervious surface,and the city landscape has undergone great changes.The change of urban impervious surface has become an important index to characterize the degree of urbanization.At the same time,the city impervious surface also contains the characteristics of strong regenerative capacity,poor water storage capacity and obstruction of airflow transmission,as well as an important index to measure the urban environmental quality,which can be used to study the ecological effect of urbanization.In the study of ecological environment effect of urban impervious surface,the change of urban surface temperature has been paid much attention by many scholars.The research on the water surface and surface temperature of the city mainly concentrates on the description of space-time evolution,and the correlation between the two is verified by many research results.However,there are few studies on the relationship between the surface temperature and the impervious surface by fractal theory.At present,with the concept of ecological restoration,urban remediation,urban renewal,sponge city and so on,the impervious landscape is integrated into the urban environment,and the quantitative relationship between surface water and surface temperature is more important,and single profile analysis is difficult to meet the requirements.Therefore,on the basis of previous studies,in order to further explore the characteristics of time and space change of impervious surface and surface temperature,the oasis city in arid area was chosen as the research area,and the theory of geography,landscape ecology,fractal theory and systematics were used to analyze the variation intensity of the water surface type,change direction and landscape pattern characteristics,and its influence on the surface temperature of the quantitative analysis,to explore the change of the law,the impact of the water surface and surface temperature on the urban ecosystem,to optimize the urban ecosystem has a certain guiding significance for urban planning related departments in the overall layout of urban development to provide a reference.The main research contents and conclusions are as follows:(1)The surface index of the 2000-2016-year study area was obtained by the normalized difference of surface index.The results show that the average value of the water surface index in cities is the rising trend of fluctuation.Since 2000,there are few internal differences in the surface index of the study area,and the spatial distribution is less dispersed.The Urumqi surface area of high coverage has increased markedly,east of the east of the outer ring and north of the Northern Ring movement is significant;Karamay surface is also gradually extended from the main urban area,of which the main urban area from the road formed by the surface of the water is significantly increased;the distribution of Kuerlei water surface mainly with the Peacock River,The main canal and the Jaracu canal were opened and spread outward,and the Hami of the water surface showed the transformation of dot to linear and reticular.In 2000-2006,2006-2011,2011-2016 three periods,the Urumqi surface index is dominated by the change trajectory of descending-ascending-descending,and the Karamay,Kuerlei,Hami not penetrating the water surface are mainly the change trajectories of descending-ascending-ascending.In the change of gravity center shift,the displacement distance of the center of gravity with no cover,low cover and full coverage is larger.Urumqi,Karamay water surface type agglomeration is obvious,the full coverage of the landscape in the region dominated,Kuerlei,Hami not permeable surface landscape types are basically unchanged.Urumqi,Kuerlei the connectivity of various types of plaques,Karamay,Hami the connectivity of various plaques weakened.The shape of the surface landscape is more complicated than that in the study area,especially in the whole coverage type.(2)Through the Fractal Study of box dimension,it is found that the scale invariance exists both on axis and whole region.The water surface index in the study area is mainly concentrated in the 0.5-0.7,the number of the interval is obvious growth trend,many of the low permeable surface area is transformed into the relatively high impervious surface,and the distribution is more and more concentrated and relatively close.There is a positive long Cheng correlation characteristic in the water surface,the distribution of the impervious surface is not random,it is the layout under certain law,and the aggregation distribution is high and low in space.The increase of the surface of a certain element in the study area will affect the growth of the surface index of the surrounding pixels,conversely,the decrease of the surface of a certain image element,also bring about the decrease of the surface index of the surrounding pixels,and the adjacent pixels are not permeable to the surface water surface.(3)The spatial distribution of surface temperature in 4 phases of the study area is obtained by inversion of surface temperature based on single channel algorithm.Since 2000,the surface temperature of Urumqi has been increasing obviously,and the surface temperature in other areas has not changed much.The high temperature area of Urumqi is mainly concentrated in the main urban area,which has the trend of spreading to the suburbs;the surface temperature of the Karamay is relatively low,the area of the area is expanding gradually,extending to the periphery is obvious;the surface temperature of Kuerlei is characterized by the West low East High.The spatial distribution of Hami surface temperature shows that the region with lower temperature is decreasing,and the heat in the northeast is weakening.Through the analysis of box dimension,it is found that the self-similarity of surface temperature spatial distribution is obvious.The spatial distribution of Urumqi,Karamay and Kuerlei,which is higher than the mean of surface temperature,tends to be decentralized and homogeneous,and the data points Hami higher than the mean of surface temperature tend to be concentrated.In the center of gravity transfer of different types of surface temperature,the overall migration distance of low temperature zone,sub low temperature zone and high temperature region is large.The spatial distribution of surface temperature in the study area is characterized by long term correlation,that is,the surface temperature in each image element is not randomly distributed,and the relationship between the image elements is shown as the same change trend.(4)Select the Urumqi in the research area to analyze the relationship between the surface temperature and the water surface,and find out the non-linear relationship between the two,and show a certain stage characteristic by the density segmentation.From no cover to high coverage,the corresponding surface temperature shows a rising trend.Different types of surface temperature spatial difference is obvious,and the difference of surface temperature is significant.In the course of Impervious surface type change,it mainly converts to high coverage type.The surface temperature of the orbit with high coverage has been low and the contribution is the highest.In addition to low coverage,the surface temperature of other Impervious surface cover types is significantly correlated.The correlation between water surface landscape pattern index and surface temperature is relatively complex,and different types of impervious surface are obvious.On the axis analysis,there is a positive correlation between the surface temperature and the Impervious surface index,and the positive correlation between the power law of the north and South axes is obvious,and the relationship between the east and West axes is relatively complex.In the Multifractal spectrum analysis,the surface temperature in 2000,2011 and 2016 is more correlated with the long distance of the Earth.(5)Taking Urumqi as a typical case,the ecological index of urban remote sensing is constructed by four components of green degree,humidity,heat and dryness,and the influence of surface temperature and impervious surface on urban ecosystem is further analyzed.Since 2000,the ecological index of Urumqi remote sensing rose from a weak,but the ecological index of the whole study area was still low,the ecological index reached the level of good and excellent,the overall ecological environment level was not high.The Urumqi remote Sensing Ecological Index mainly concentrates on the variation of a differential range.In the northern part of Urumqi,the ecological whole is better than that in the south,the patches in the High ecological index region are shifted to the south,and the ecology in the southern region is further improved.The ecological index of remote sensing of different grade types has obvious shape complexity and aggregation enhancement.Many factors play an important role in the ecosystem,in which the contribution of vegetation to the system is greater,and the surface temperature and impervious to the ecological environment are obviously inhibited. |
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