Mapping the extent of urban creep in Exeter using OBIA

摘要

Our towns and cities are constantly changing and with this change brings increased pressures on residents, the environment and those tasked with managing them. At the forefront of this change is new development, especially that which displaces natural landscapes, and as such this type of change is controlled and typically well recorded. There is a wealth of information about how towns and cities grow, but what about the change to existing urban areas? Modern lifestyles have led to a recent increase in the amount of paved areas of existing properties typically displayed as front garden parking and low maintenance back gardens. Within the water industry this phenomenon is termed 'urban creep' and it is an emerging problem in urban drainage and flooding. This study uses Object Based Image Analysis (OBIA) to classify urban creep across the Exeter region. Multitemporal VHR aerial imagery is supplemented by a high resolution land cover classification depicting the surface types present in the most recent time interval. The importance of the land cover layer is shown by allowing a domain specific change classification, and crucially labelling of that change. The resultant labelled change enabled urban creep to be identified by spatial analysis whereby change associated with new development can be filtered out by association to new building objects. The study has identified that urban creep not only represents a significant proportion of total change but actually equates to 0.62% of the total area of Exeter district in only 3 years. These results will be discussed in relation to the study area and the implications this may have over time.