Study On Measurement Of Spatial And Temporal Characteristics Of Urban Sprawl Of Lianyungang City

In2008, the urban population exceeded the rural population for the first time in history, and urbanization in developing countries would keep the fast pace. However, ecological and environmental problems caused urbanization become increasingly serious and urban sprawl has become a major issue facing many metropolitan areas. Urban sprawl resulted in two consequences directly, one is competing for land resources, and the other is degeneration of ecosystem. Urban sprawl gradually emerges in China and will be an obstacle to modernization if it couldn’t be curbed effectively, as pointed out by academician Lu Dadao. It is critically important to properly characterize urban sprawl in order to response to such problem.This paper attempted to measure the spatial and temporal characteristics of urban sprawl based on two urban landscape characteristics:composition and configuration. Composition characteristic included two dimensions:variation degree, substitute relation. Configuration characteristic included three dimensions:fragmentation, dominance and leaping degree.9metrics were calculated:(1) Percentage of Landscape,(2) Intensity of Built-Up Area Expansion, and (3) Subregional Contribution of Built-Up Area Expansion reflected variation degree;(4) Contribution Rate to New Built-up land and (5) Replacement Rate reflected substitute relation;(6) Patch Density and (7) Mean Patch Area reflected fragmentation,(8) Largest Patch Index reflected dominance;(9) Leapfrog Index reflected leaping degree.Lianyungang city is one of the coastal regions with rapid urbanization progress in China. This paper took the main area of the "one body two wings" development structure proposed by Lianyungang Urban Master Plan (2008-2030) as study area and divided study area into3sub regions. Method motioned above was taken to measure the spatial and temporal characteristics and progress of urban sprawl of study area in6periods from1989to2011(1989,1995,2000,2006,2009,2011). The results indicated:(1) urban sprawl characteristics were obvious in study area during study periods, characterized by increase of built-up land area and dispersedness of built-up land patches;(2) urban sprawl tendency in study area retarded during the last three periods, characterized by decrease of intensity of built-up area expansion and dispersedness of built-up land patches;(3) built-up land trended to expand towards the sea since2006, because coastal wetlands, such as salt field and culture ponds were encroached and shared more of the newly increased built-up land;(4) urban sprawl progress caused significant change of landscape pattern in study area, meanly presented as following phenomena:a large number of natural/semi-natural landscape transformed to built-up land, fragmentation degree of farmland and green land increased sharply, and built-up land became the predominant landscape.