Quantifying the physical composition of urban morphology throughout Wales based on the time series (1989-2011) analysis of Landsat TM/ETM+ images and supporting GIS data

摘要

Knowledge of impervious surface areas (ISA) and on their changes in magnitude, location, geometry and morphology is significant for a range of practical applications and research alike. It is a key indicator of global environmental change and is also important parameter for urban planning and environmental resources management. Despite this, use of Earth Observation (EO) technology in mapping ISAs within the European Union (EU) and in particular in the UK is inadequate. In the present study, study sites across Wales have been used to test the use of freely distributed EO data from Landsat TM/ETM+ sensors in retrieving ISA for improving the current European estimations of urbanization and soil sealing. A traditional classifier and a linear spectral mixture analysis (LSMA) were both applied to a series of images acquired over a period spanning 22 years to extract ISA. Aerial photography with a spatial resolution of 0.4m was used for validation purposes. The Welsh study areas provided a unique chance to detect largely dispersed urban morphology within an urban-rural frontier context. The process tree built and presented in this study is important in terms of moving forward into a biennial program for the Welsh Government. Our methodology not only inaugurates the local retrieval of ISA for Wales but also meliorates the existing EU international figures. With the recent launch of Landsat 8, our study can provide important input to efforts focusing towards the development of a global scale operational cost-effective and consistent long term monitoring of ISA based on EO technology.