Quatifying spatiotemporal patterns dynamics of impervious surface in Shenzhen

Rapid urbanization has changed urban land cover characteristics.Impervious surface has been the main land cover categories in urban landscape.How to quantify the spatial pattern of impervious surface and its temporal change are necessary for us to understand the dynamics of processes and patterns of urban landscape and their relationship between impervious surface and other heterogeneous landscapes.Remote sensing technology has been widely applied in urban impervious surface monitoring and change detection,but the spatial pattern and temporal change of impervious surface is rarely concerned.Taking Shenzhen as a case study area,we quatify the spatiotemporal patterns dynamics of impervious surface from 1990 to 2005.In order to analyze the spatial temporal change of impervious surface,we used an index of impervious surface area to show the heterogonous of impervious surface by linear spectral mixture method,which can be divided into six cover degrees.We use the matrix change method to explain the changes among four time periods and 3 stages and landscape pattern metrics to indicate the pattern change at three different levels.Results show that there were three changing types in the 15 years,namely,high and full density impervious surface area(HDISA,FDISA respectively)-continued increasing,and medium density(MDISA) and low density(LDISA)—first increased and then decreased,while natural surface(NOISA) and very low density(VLISA) are contrary to MDISA and LDISA.However,the pattern of impervious surface indicates that cover degrees had a high landscape diversity and the value changed from low to high then decreased and reached a new high level.The landscape aggregation was very low overall in the four time periods,but had a significant fluctuation in classes level.The patches shape shows that natural surface had a high dominant position in 1990,but after that changed to medium density impervious surface and high density overtook the second position after 2005.Our research can provide a basis for the orderly development for planning urban impervious surface extension and aggregation;however,we also believe that mitigating the expansion of impervious surface is benefit to the improvement of the urban ecological and environmental quality.