Research On Correlation Between Road Density And Settlement Percentage Coverage In Jiangsu Province

With the rapid development of economy in our country, developed areas had accelerated their urbanization process, and also, size of urban settlements had increased. Studying the relationship between settlements’ spatial patterns and it’s ecological processes had become a focus in the studies of urban ecology. Roads are channels supporting stream of people and material flow among settlement groups. With the increase of settlement scale, roads that connect settlement groups will also increase rapidly. In different ecosystems, roads and settlements form various landscape patterns. There are complex interactions between the two important landscape elements (road and settlement).During the forming and developing process of cities, road system and urban settlements interact with each other. Firstly, the attachment relationship between urban settlements generates connecting demand, causing the continuous development of road system, and secondly, the improvement of road system promotes the development of urban network, guides the space layout of settlements, and makes it perfect by feedback. Space extension of urban settlements has the corridor effect, and the road system changes the spatial pattern and extending direction of settlement the of and space by changing the land use structure. Accurately revealing the interaction and influence mechanism between the two landscape elements is advantageous to reasonable planning of road system, scientific regulation of urban and rural development scale and rational utilization of land resources, promoting the realization of regional sustainable development goals.The scientific rationality of research on landscape pattern issue depends on selecting the proper scale. Of the two landscape elements in this paper, road is a kind of perfoliate, linear element across the whole landscape or even several landscape zones, and the dynamic change is consistent with the overall trend on large landscape scale; while settlement is a kind of patch element, and the dynamic change is more likely to be influenced by the condition on small scale. Given the difference of scale characteristic of the two elements, it is necessary to consider their own scale dependencies and choose different observation scales when researching the relationship between road and the settlement. And then we should compare the associated intensity of road and the settlement of different scale pairs in order to determine the most appropriate pair under which we study the relationship between the two elements.Comprehensive economic strength of Jiangsu province has been in the front row of the country. In recent years, urbanization and city modernization level in Jiangsu province have been increasing steadily. By the end of2012, the urbanization rate reached to63%, well above the national average level. Changes in land use status brought by the urbanization is also obvious, mainly are growth of scale of settlements and all kinds of urban construction land. Jiangsu Province is one of the three central provinces in the Yangtze River Delta and the settlement dynamic of this province has certain representativeness of this region. What’s more, Jiangsu Province is an important transportation hub in East China, with the highway mileage currently ranking among the top nationwide. This article chooses Jiangsu Province as the study area, which is of great reference value for the development of other provinces and cities of the Yangtze River Delta and even of the whole country.Based on1:10000topographic map of Jiangsu Province, this paper studied the distributing characteristics of road density (RD) and settlement percentage coverage (SPC) of15counties in Jiangsu Province at the scale of5,10,15and20km with the method of Neighborhood Statistics, and then compared the degree of correlation between RD and SPC at16scale pairs of each county, and further studied the relation between RD and SPC at appropriate scale pairs of each county in order to reveal the relation between settlement and road system more accurately. The results showed that road and settlement are types of landscape elements of different characteristics, and are closely interacted with each other.For the same RD-SPC type, heterogeneity of road and settlement both decreased with increasing scales; At the same scale, heterogeneity of settlement in the areas with higher SPC tended to be lower but could increase slightly as the SPC increased further. However, heterogeneity of road decreased with increasing RD.At the same scale, spatial heterogeneity of road are always lower than that of settlement. What’s more, the decreased degree of heterogeneity of road with increasing scales was significantly lower than that of the latter. The above two results indicated that road and settlement are types of landscape elements of different heterogeneity levels and different scale-dependency characteristics.Correlation intensity of road density and settlement percentage coverage are of significant difference under different observation scale pairs. However, certain regularity was also found. When observation scale of settlement was fixed, correlation intensity of the two elements enhanced with increasing observation scale of road; But on the contrary, when observation scale of road was fixed, correlation intensity of the two elements weakened with increasing observation scale of settlement. When studying the relationship between road and settlement, we had better choose a larger observation scale for road and a smaller observation scale for settlement, in this paper, the suitable observation scales for road and settlement are20km and5km respectively.Because of the fact that different landscape elements tend to be of different scale-dependency characteristics, it is necessary to choose appropriate observation scale pairs when studying the correlation between two landscape elements. In this paper, we studied the relationship between road density and settlement percentage coverage at the most appropriate observation scale pair, the results showed that:in spite of the fact that the studied counties belong to different RD-SPC types and the regional road and settlement scale are significantly different, the patterns that road density increased with the increasing settlement percentage coverage were very similar. The pattern was:road density at the20km scale showed ladder-like growth with the increase of settlement percentage coverage at the5km scale, while discontinuous growth of RD was shown. Construction of road system is forward-looking and stepped, so that the changing curve of road density is discontinuous along with the increasing settlement system.